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Warm-UP: What do you think is happening to this cell? Homework: 10 Key Ideas Section 12.1 AP Test Money DUE: NEXT FRIDAY! 3/6 Remember, the 2 nd semester.

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Presentation on theme: "Warm-UP: What do you think is happening to this cell? Homework: 10 Key Ideas Section 12.1 AP Test Money DUE: NEXT FRIDAY! 3/6 Remember, the 2 nd semester."— Presentation transcript:

1 Warm-UP: What do you think is happening to this cell? Homework: 10 Key Ideas Section 12.1 AP Test Money DUE: NEXT FRIDAY! 3/6 Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too!

2 Topics Concept 13.1: What are the advantages to sexual/asexual reproduction? What is the relationship between a gene, a chromosome, and DNA? Concept 13.2: What happens to a cell during meiosis? Compare mitosis and meiosis? Why bother doing meiosis? Concept 13.4: When is genetic diversity increased during meiosis? How? What is the advantage to this? Concept 14.1: How can we predict the offspring of parents using punnett squares (monohybrid, dihybrid)? Explain why some traits are dominant to others. Explain how variation is increased due to independent assortment. Concept 14.2: Use probability laws to solve punnett squares predicting the outcomes of crosses where many traits are involved. Concept 14.3: Inheritance patterns are more complex that simple dominance/recessive: incomplete dominance, blood types, codominance Concept 14.4: Use a pedigree analysis of a family to make predictions about future offspring. Concept 15.1: What did Morgan tell us that Mendel couldn’t? How do chromosomes explain Mendel’s 3:1 ratio? Concept 15.2: Explain how sex is determined. Why do some diseases show in boys more often than girls? Concept 15.3: How do linked genes complicate Mendel’s findings? Essential Knowledge 3.a.2: In eukaryotes, heritable info. is passed to the next generation via mitosis and meiosis 3.a.3: The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring 3.a.4: The inheritance pattern of many traits cannot be explained by simple Mendelian genetics 3.c.2: Biological systems have multiple processes that increase genetic variation

3 Unit 7: Inheritance Big Idea: Big Idea: In eukaryotic organisms, heritable information is passed to the next generation via mitosis and meiosis, which has multiple processes that increases genetic variation. The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. The chromosomal basis of inheritance explains pattern of transmission of genes from parent to offspring.

4 Time (seconds) DrawingDescription 0:25 – 0:30 – 0:35– 0:40 – 0:45 – 0:50- In eukaryotic organisms, heritable information is passed to the next generation via mitosis and meiosis

5 Chromosome Model Materials: pipe cleaners beads cotton balls tape string Materials: pipe cleaners beads cotton balls tape string Procedure 1. add 3-5 beads to a pipe cleaner to model genes 2. twist a 2 nd pipe cleaner to the 1 st to model the double helix 3. tie string to the beads to model mRNA 4. wrap the whole model around a cotton ball to represent how DNA supercoils around histones in order to get smaller 5. replicate the 1 st to model a sister chromatid 6. tape it to the 1 st at about the middle to model the centromere Procedure 1. add 3-5 beads to a pipe cleaner to model genes 2. twist a 2 nd pipe cleaner to the 1 st to model the double helix 3. tie string to the beads to model mRNA 4. wrap the whole model around a cotton ball to represent how DNA supercoils around histones in order to get smaller 5. replicate the 1 st to model a sister chromatid 6. tape it to the 1 st at about the middle to model the centromere

6 Chromosome Model Procedure 1. add 3-5 beads to a pipe cleaner to model genes 2. twist a 2 nd pipe cleaner to the 1 st to model the double helix 3. tie string to the beads to model mRNA transcribing DNA 4. wrap the whole model around a cotton ball to represent how DNA supercoils around histones in order to get smaller 5. replicate the 1 st to model a sister chromatid 6. tape it to the 1 st at about the middle to model the centromere Procedure 1. add 3-5 beads to a pipe cleaner to model genes 2. twist a 2 nd pipe cleaner to the 1 st to model the double helix 3. tie string to the beads to model mRNA transcribing DNA 4. wrap the whole model around a cotton ball to represent how DNA supercoils around histones in order to get smaller 5. replicate the 1 st to model a sister chromatid 6. tape it to the 1 st at about the middle to model the centromere Parts chromosome: tightly coiled DNA double helix: DNA is 2 strands of nucleotides twisted together. gene: small sections of DNA that encode traits histone: proteins that DNA supercoils around; makes the DNA smaller so that it can fit in our cells sister chromatid: a duplicated copy of the original DNA, still connected to the 1 st centromere: the place where the 2 sister chromatids are connected (DNA Replication not quite finished) mRNA: copies of DNA that read genes Parts chromosome: tightly coiled DNA double helix: DNA is 2 strands of nucleotides twisted together. gene: small sections of DNA that encode traits histone: proteins that DNA supercoils around; makes the DNA smaller so that it can fit in our cells sister chromatid: a duplicated copy of the original DNA, still connected to the 1 st centromere: the place where the 2 sister chromatids are connected (DNA Replication not quite finished) mRNA: copies of DNA that read genes

7 Chromosome Model Materials: pipe cleaners beads cotton balls tape Materials: pipe cleaners beads cotton balls tape Parts chromosome: tightly coiled DNA double helix: DNA is 2 strands of nucleotides twisted together. gene: small sections of DNA that encode traits histone: proteins that DNA supercoils around; makes the DNA smaller so that it can fit in our cells sister chromatid: a duplicated copy of the original DNA, still connected to the 1 st centromere: the place where the 2 sister chromatids are connected mRNA: copies of DNA that read genes Parts chromosome: tightly coiled DNA double helix: DNA is 2 strands of nucleotides twisted together. gene: small sections of DNA that encode traits histone: proteins that DNA supercoils around; makes the DNA smaller so that it can fit in our cells sister chromatid: a duplicated copy of the original DNA, still connected to the 1 st centromere: the place where the 2 sister chromatids are connected mRNA: copies of DNA that read genes

8 Chromosome Model Materials: pipe cleaners beads cotton balls tape Materials: pipe cleaners beads cotton balls tape Parts chromosome: tightly coiled DNA double helix: DNA is 2 strands of nucleotides twisted together. gene: small sections of DNA that encode traits histone: proteins that DNA supercoils around; makes the DNA smaller so that it can fit in our cells sister chromatid: a duplicated copy of the original DNA, still connected to the 1 st centromere: the place where the 2 sister chromatids are connected mRNA: copies of DNA that read genes Parts chromosome: tightly coiled DNA double helix: DNA is 2 strands of nucleotides twisted together. gene: small sections of DNA that encode traits histone: proteins that DNA supercoils around; makes the DNA smaller so that it can fit in our cells sister chromatid: a duplicated copy of the original DNA, still connected to the 1 st centromere: the place where the 2 sister chromatids are connected mRNA: copies of DNA that read genes

9 Chromosome Model Materials: pipe cleaners beads cotton balls tape Materials: pipe cleaners beads cotton balls tape Parts chromosome: tightly coiled DNA double helix: DNA is 2 strands of nucleotides twisted together. gene: small sections of DNA that encode traits histone: proteins that DNA supercoils around; makes the DNA smaller so that it can fit in our cells sister chromatid: a duplicated copy of the original DNA, still connected to the 1 st centromere: the place where the 2 sister chromatids are connected mRNA: copies of DNA that read genes Parts chromosome: tightly coiled DNA double helix: DNA is 2 strands of nucleotides twisted together. gene: small sections of DNA that encode traits histone: proteins that DNA supercoils around; makes the DNA smaller so that it can fit in our cells sister chromatid: a duplicated copy of the original DNA, still connected to the 1 st centromere: the place where the 2 sister chromatids are connected mRNA: copies of DNA that read genes

10 Warm-UP: Can you “unwind” your model like in the picture to show the parts? Sketch and label your model (or the picture of the model). Labels: histone, mRNA, DNA, sister chromatid, centromere AP Test Money DUE: 3/6 Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too! Homework for Tonight: Mitosis Worksheet UNIT 7/8 TEST: March 19 th Inheritance and Regulation Due Now: Stamp Sheet

11 Warm-UP: 1.Is blowing up a balloon a good model for how cells or organisms grow? Explain 2.In what ways are cells different than each other? the same? AP Test Money DUE: 3/6 Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too! Homework for Tonight: 12.2 UNIT 7/8 TEST: March 19 th Inheritance and Regulation

12 AP Test Money DUE: 3/6 Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too! Homework for Tonight: Warm-UP: 1.Is blowing up a balloon a good model for how cells or organisms grow? Explain 2.In what ways are cells different than each other? the same?

13 AP Test Money DUE: 3/6 Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too! Homework for Tonight: Warm-UP: 1.Is blowing up a balloon a good model for how cells or organisms grow? Explain 2.In what ways are cells different than each other? the same?

14 AP Test Money DUE: 3/6 Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too! Homework for Tonight: Warm-UP: 1.Is blowing up a balloon a good model for how cells or organisms grow? Explain 2.In what ways are cells different than each other? the same?

15 In eukaryotic organisms, heritable information is passed to the next generation via mitosis and meiosis Cell Division: 2 Types: Mitosis and Meiosis Mitosis Purpose: growth repair asexual reproduction (actually binary fission in prokaryotes) occurs after DNA replication is followed by cytokinesis 2 genetically identical daughter cells (clones) Steps: 1.Replication 2.Alignment 3.Separation

16 1.Draw a big cell with a nucleus inside. 2.Add homologous pairs of chromosomes: – 1 big yellow, 1 big white – 1 medium yellow, 1 medium white – 1 small yellow, 1 small white 3.Clone each chromosome (DNA Replication) (making sister chromatids) 4.Nucleus breaks down (erase it). 5.Clones separate: one to each side of cell 6.Cytokinesis: cell membrane "grows" between the 2 halves 7.Nucleus "grows" around chromosomes Mitosis Modeling When you’re confident on the process, show Mr. Jones.

17 In your notebook: Table 12.7: Stages of Mitosis: p.232 At each stage, describe what is happening in 1- 2 sentences. DO NOT COPY DRAW with LABELS: cell membrane nucleus chromosome DNA replication cytokinesis sister chromatid Mitosis Modeling

18 Analysis 1.What is the outcome of mitosis? 2.What steps of mitosis ensure a perfect outcome? 3.If the first cell has 46 chromosomes (before cloning), how many does each daughter cell have? 4.Why do cells go through mitosis? Mitosis Modeling

19 Words to Know: Nucleus DNA Histones Chromatin Chromosome Chromatid Centromere Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Interphase: “S” phase Mitosis:

20 Warm-UP: 1.Advantages of Sex? 2.Disadvantages of Sex? AP Test Money DUE: 3/6 Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too! Homework DUE Thurs: Meiosis Wksht UNIT 7/8 TEST: March 19 th Inheritance and Regulation

21 Fig Bacteria Parent Bud 0.5 mm Asexual Reproduction Advantages: 1.Can be done in isolation. 2.If you are perfect, why change? Best when an organism is “perfectly” suited for its environment 3.Less “machinery” needed: no waste on flowers, “new” types of cells, or other secondary sexual characteristics Disadvantages: 1.Less variety: Poor option in a changing environment Plants

22 Fig Parent Bud 0.5 mm Asexual Reproduction Advantages: 1.Can be done in isolation. 2.If you are perfect, why change? Best when an organism is “perfectly” suited for its environment 3.Less “machinery” needed: no waste on flowers, “new” types of cells, or other secondary sexual characteristics Disadvantages: 1.Less variety: Poor option in a changing environment

23 Fig Parent Bud 0.5 mm Asexual Reproduction Advantages: 1.Can be done in isolation. 2.If you are perfect, why change? Best when an organism is “perfectly” suited for its environment 3.Less “machinery” needed: no waste on flowers, “new” types of cells, or other secondary sexual characteristics Disadvantages: 1.Less variety: Poor option in a changing environment Aspen

24 Fig Sexual Reproduction Advantages: 1.Increased variety: Best when environment is changing Increased Variety is DUE TO: random fertilization meiosis: independent assortment crossing-over Disadvantages: 1.Resource investment: specialized cells: gametes secondary sexual characteristics: mate attraction 2.Requires a partner (except when plants self-fertilize)

25 In eukaryotic organisms, heritable information is passed to the next generation via mitosis and meiosis Cell Division: 2 Types: Meiosis: sex cells (gametes) (sperm/eggs) Purpose: ensures that each gamete receives one complete haploid (1n) set of chromosomes Ensures chromosome number stays the same: each offspring receives ½ (1n) of the full set for the species (2n) Steps: 1.DNA Replication 2.homologous pairs form a tetrad (independent assortment) (genetic variation increases) 3. cross over between homologous chromosomes may occur (genetic variation increases) 4.Meiosis I: homologous pairs separate 5.Meiosis II: sister chromatids separate

26 In eukaryotic organisms, heritable information is passed to the next generation via mitosis and meiosis Cell Division: 2 Types: Meiosis: sex cells (gametes) (sperm/eggs) Purpose: ensures that each gamete receives one complete haploid (1n) set of chromosomes Ensures chromosome number stays the same: each offspring receives ½ (1n) of the full set for the species (2n) Steps: 1.DNA Replication 2.homologous pairs form a tetrad (independent assortment) (genetic variation increases) 3. cross over between homologous chromosomes may occur (genetic variation increases) 4.Meiosis I: homologous pairs separate 5.Meiosis II: sister chromatids separate

27 In eukaryotic organisms, heritable information is passed to the next generation via mitosis and meiosis Cell Division: 2 Types: Meiosis: sex cells (gametes) (sperm/eggs) Purpose: ensures that each gamete receives one complete haploid (1n) set of chromosomes Ensures chromosome number stays the same: each offspring receives ½ (1n) of the full set for the species (2n) Steps: 1.DNA Replication 2.homologous pairs form a tetrad (independent assortment) (genetic variation increases) 3. cross over between homologous chromosomes may occur (genetic variation increases) 4.Meiosis I: homologous pairs separate 5.Meiosis II: sister chromatids separate

28 1.Build your diploid cell (an homologous pair for each chromosome) a.Draw a big cell with a nucleus inside. b.Add homologous pairs of chromosomes: 1 big white, 1 big yellow 1 medium white, 1 medium yellow 1 small white, 1 small yellow 2.Clone each chromosome (DNA Replication) (making sister chromatids) 3.Nucleus breaks down (erase it). 4.Homologous pairs form a tetrad: crossing over may occur. (note: do not model crossing over for now) 5.Homologous pairs separate one to each side of cell: all paternal (or all maternal) do NOT have to go together (independent assortment) 6.Cytokinesis: cell membrane "grows" between the 2 halves 7.Clones (sister chromatids) separate (centromere “breaks” as DNA polymerization completes): one to each side of cell 8.Cytokinesis: cell membrane "grows" between the 2 halves 9.Nucleus "grows" around chromosomes. 4 cells made (gametes, which have half the number of chromosomes (haploids) Meiosis Modeling When you’re confident on the process, show Mr. Jones.

29 Meiosis Modeling When you’re confident on the process, show Mr. Jones. In your notebook: Table 13.8: Stages of Meiosis: p.255 At each stage, describe what is happening in 1-2 sentences. DO NOT COPY DRAW with LABELS: cell membrane nucleus chromosome DNA replication cytokinesis sister chromatid crossing over recombinant chromosome independent assortment Meiosis I Meiosis II

30 Meiosis Modeling Analysis 1.What is the outcome of meiosis? 2.What steps of meiosis cause variation? 3.If the first cell has 46 chromosomes (before cloning), how many does each daughter cell have? 4.How many unique gametes did you form? How many could have formed? 5.Why do cells go through meiosis?

31 Warm-UP: 1. Why do meiosis? 2. How does meiosis increase variation in organisms? AP Test Money DUE: 3/6 Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too! Homework DUE Tomorrow: Meiosis Wksht UNIT 7/8 TEST: March 19 th Inheritance and Regulation

32 Meiosis has multiple processes that increases genetic variation Genetic Variation is due to: Mutations (last unit) Meiosis: Independent assortment of chromosomes: paternal (red) chromosomes may/may not move together during Meiosis I –causes an organism with n homologous pairs to be able to produce 2 n varieties of gametes instead of only 2 –ex: humans: 2 23 =8,388,608 Crossing over: swapping of sections of homologous pairs during Meiosis I; produces recombinant chromosomes –causes “linked” genes to become “unlinked”: 2 alleles on the same chromosome may/may not move together during Meiosis I –recombinant chromosomes have unique combinations of alleles Random fertilization: the particular combination of egg and sperm that results in the offspring is not predictable –ex: humans: dad’s varieites of sperm (8,388,608) and mom’s varieites of eggs (8,388,608) can produce varieties 70,368,744,177,664 offpring

33 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Meiosis has multiple processes that increase genetic variation Genetic Variation is due to: Mutations (last unit) Meiosis: Independent assortment of chromosomes: paternal (red) chromosomes may/may not move together during Meiosis I –causes an organism with n homologous pairs to be able to produce 2 n varieties of gametes instead of only 2 –ex: humans: 2 23 =8,388,608 Crossing over: swapping of sections of homologous pairs during Meiosis I; produces recombinant chromosomes –causes “linked” genes to become “unlinked”: 2 alleles on the same chromosome may/may not move together during Meiosis I –recombinant chromosomes have unique combinations of alleles Random fertilization: the particular combination of egg and sperm that results in the offspring is not predictable –ex: humans: dad’s varieites of sperm (8,388,608) and mom’s varieites of eggs (8,388,608) can produce varieties 70,368,744,177,664 offpring

34 Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Meiosis has multiple processes that increase genetic variation Genetic Variation is due to: Mutations (last unit) Meiosis: Independent assortment of chromosomes: paternal (red) chromosomes may/may not move together during Meiosis I –causes an organism with n homologous pairs to be able to produce 2 n varieties of gametes instead of only 2 –ex: humans: 2 23 =8,388,608 Crossing over: swapping of sections of homologous pairs during Meiosis I; produces recombinant chromosomes –causes “linked” genes to become “unlinked”: 2 alleles on the same chromosome may/may not move together during Meiosis I –recombinant chromosomes have unique combinations of alleles Random fertilization: the particular combination of egg and sperm that results in the offspring is not predictable –ex: humans: dad’s varieites of sperm (8,388,608) and mom’s varieites of eggs (8,388,608) can produce varieties 70,368,744,177,664 offpring

35 Meiosis has multiple processes that increases genetic variation Genetic Variation is due to: Mutations (last unit) Meiosis: Independent assortment of chromosomes: paternal (red) chromosomes may/may not move together during Meiosis I –causes an organism with n homologous pairs to be able to produce 2 n varieties of gametes instead of only 2 –ex: humans: 2 23 =8,388,608 Crossing over: swapping of sections of homologous pairs during Meiosis I; produces recombinant chromosomes –causes “linked” genes to become “unlinked”: 2 alleles on the same chromosome may/may not move together during Meiosis I –recombinant chromosomes have unique combinations of alleles Random fertilization: the particular combination of egg and sperm that results in the offspring is not predictable –ex: humans: dad’s varieites of sperm (8,388,608) and mom’s varieites of eggs (8,388,608) can produce varieties 70,368,744,177,664 offpring

36 Warm-UP: Watch the video. What is happening? Why does this happen? How does this increase variation? AP Test Money DUE: TOMORROW 3/6 Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too! Homework DUE Tomorrow: ???? UNIT 7/8 TEST: March 19 th Inheritance and Regulation

37 Fig. 13-9a MITOSIS MEIOSIS MEIOSIS I Prophase I Chiasma Chromosome replication Homologous chromosome pair Chromosome replication 2n = 6 Parent cell Prophase Replicated chromosome Metaphase Metaphase I Anaphase I Telophase I Haploid n = 3 Daughter cells of meiosis I MEIOSIS II Daughter cells of meiosis II n n n n 2n2n 2n2n Daughter cells of mitosis Anaphase Telophase

38 Compare: Contrast: Independent Assortment Crossing-overSexual FertilizationMutation Types of Changes to Cells: Think About : what, where, when, how, how much variation created

39 Warm-UP: Now we need to keep track of the genes on the chromosomes that are inherited. Notice the letters on the chromosomes. They represent different alleles for Huntington's. Barbie has Huntington's. What is the chance her child will get Huntington's? AP Test Money DUE: 3/6: TOMORROW Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too! Homework DUE Tomorrow: 14.1: 5 Key Ideas AND Concept Check #1-3 H=dominant (remember, Huntington’s is dominant) h=recessive (no Huntington’s) Homework DUE Monday: Test Corrections for 10% Make-UP

40 Warm-UP: Talk about your Concept Check with your table team. Do you have agreement? Do you have questions? AP Test Money DUE: 3/6: TODAY Remember, the 2 nd semester Final Exam will be an AP test (the week before the official AP test); you might as well take the official test too! DUE next Thursday: Monohybrid Crosses Homework DUE Monday: Test Corrections for 10% Make-UP

41 Warm-UP: Now we need to keep track of TWO UNLINKED genes on the chromosomes that are inherited. Notice the letters on the chromosomes. They represent different alleles for Huntington's and red hair color. Barbie has Huntington's and is a blond (but a carrier). Ken does not have Huntington’s and is also a carrier for red hair. What is the chance their child will get Huntington's and red hair? Homework DUE Tomorrow: 14.2: 5 Key Ideas AND Concept Check #1-3 H= Huntington’s h=no Huntington’s R= no red hair r= red hair DUE Now: Test Corrections for 10% Make-UP UNIT 7/8 TEST: March 19 th Inheritance and Regulation

42 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Mendel: 1857 P: Crossed purebreds F1: all one phenotype F2: 3:1 ratio Conclusion: 1.“Alleles” segregate (in meiosis) independently 2.Some alleles (dominant) hide the expression of others (recessive) 3.Recessive alleles can appear again IF the dominant are no longer present Terms: allele: variety of a gene homozygous: both alleles are the same (purebred) heterozygous: alleles are different (carriers) (hybrids) Mendel: 1857 P: Crossed purebreds F1: all one phenotype F2: 3:1 ratio Conclusion: 1.“Alleles” segregate (in meiosis) independently 2.Some alleles (dominant) hide the expression of others (recessive) 3.Recessive alleles can appear again IF the dominant are no longer present Terms: allele: variety of a gene homozygous: both alleles are the same (purebred) heterozygous: alleles are different (carriers) (hybrids)

43 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Mendel: 1857 P: Crossed purebreds F1: all one phenotype F2: 3:1 ratio Conclusion: 1.“Alleles” segregate (in meiosis) independently 2.Some alleles (dominant) hide the expression of others (recessive) 3.Recessive alleles can appear again IF the dominant are no longer present Terms: allele: variety of a gene homozygous: both alleles are the same (purebred) heterozygous: alleles are different (carriers) (hybrids) Mendel: 1857 P: Crossed purebreds F1: all one phenotype F2: 3:1 ratio Conclusion: 1.“Alleles” segregate (in meiosis) independently 2.Some alleles (dominant) hide the expression of others (recessive) 3.Recessive alleles can appear again IF the dominant are no longer present Terms: allele: variety of a gene homozygous: both alleles are the same (purebred) heterozygous: alleles are different (carriers) (hybrids)

44 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Mendel: 1857 P: Crossed purebreds F1: all one phenotype F2: 3:1 ratio Conclusion: 1.“Alleles” segregate (in meiosis) independently 2.Some alleles (dominant) hide the expression of others (recessive) 3.Recessive alleles can appear again IF the dominant are no longer present Terms: allele: variety of a gene homozygous: both alleles are the same (purebred) heterozygous: alleles are different (carriers) (hybrids) Mendel: 1857 P: Crossed purebreds F1: all one phenotype F2: 3:1 ratio Conclusion: 1.“Alleles” segregate (in meiosis) independently 2.Some alleles (dominant) hide the expression of others (recessive) 3.Recessive alleles can appear again IF the dominant are no longer present Terms: allele: variety of a gene homozygous: both alleles are the same (purebred) heterozygous: alleles are different (carriers) (hybrids)

45 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often

46 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often

47 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often

48 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often

49 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often

50 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often

51 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often Inheritance Patterns: Simple Dominance/Recessive: Mendel monohybrid cross: one trait di or tri hybrid cross: two or three traits, assuming independent assortment laws of probability vs punnett squares incomplete dominance: phenotype of hybrids is between the phenotypes of the purebreds codominance: two dominant alleles affect the phenotype in separate, distinguishable ways polygenic inheritance: an additive effect of two or more genes on a single phenotype x-linked genes: genes on the x chromosome are expressed by boys more often than girls b.c. boys only have one x chromosome (they cannot “mask” recessive alleles) linked genes: when 2 alleles are on the same chromosome, they show up together more often

52 Warm-UP: Talk about your Concept Check with your table team. Do you have agreement? Do you have questions? Warm-UP: Talk about your Concept Check with your table team. Do you have agreement? Do you have questions? Homework DUE Tomorrow: 14.3: 5 Key Ideas AND Concept Check #1-3 DUE Now: 14.2 DUE Thursday: Monohybrid Crosses to turnitin.com DUE Friday: Dihybrid Crosses to turnitin.com UNIT 7/8 TEST: March 19 th Inheritance and Regulation

53 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Laws of Probability: skip Punnett squares instead, multiply likelyhoods

54 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Laws of Probability: skip Punnett squares instead, multiply likelyhoods ex: Chance of baby with RrYy? 1.Chance of baby with Rr? Chance of baby with Yy? Chance of baby with RrYy? 0.25

55 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Laws of Probability: skip Punnett squares instead, multiply likelyhoods ex: Chance of baby with both dominant phenotypes? 1.Chance of baby with at least one R? Chance of baby with at least one Y? Chance of baby with RrYy? (9/16)

56 The inheritance pattern of many traits cannot be explained by simple Mendelian genetics. Laws of Probability: skip Punnett squares instead, multiply likelyhoods ex: Chance of baby with both dominant phenotypes? 1.Chance of baby with at least one R? Chance of baby with at least one Y? Chance of baby with both dominant phenotypes? 1.0

57 Warm-UP: Talk about your Concept Check with your table team. Do you have agreement? Do you have questions? Warm-UP: Talk about your Concept Check with your table team. Do you have agreement? Do you have questions? Homework DUE Tomorrow: Linked vs Unlinked Genes AND Monohybrid Crosses to tunritin.com DUE Friday: Dihybrid Crosses to turnitin.com DUE Now: 14.3 UNIT 7/8 TEST: March 19 th Inheritance and Regulation

58 Warm-UP: A series of crosses is performed with fruit flies (Drosophila melanogaster) to examine inheritance of the genes vestigial (vg) and cinnabar (cn). The recessive vg allele causes small, malformed wings called vestigial wings. The recessive cn allele causes bright-red eyes called cinnabar eyes. In the first cross, a purebred female with wild- type wings and red eyes is mated with a purebred male with vestigial wings and cinnabar eyes. 1.Predict the phenotypic ratio of the F1 individuals. 2.In the second cross, female F1 flies are mated with males with vestigial wings and cinnabar eyes. Predict the phenotypic ratio of the F2 individuals. Warm-UP: A series of crosses is performed with fruit flies (Drosophila melanogaster) to examine inheritance of the genes vestigial (vg) and cinnabar (cn). The recessive vg allele causes small, malformed wings called vestigial wings. The recessive cn allele causes bright-red eyes called cinnabar eyes. In the first cross, a purebred female with wild- type wings and red eyes is mated with a purebred male with vestigial wings and cinnabar eyes. 1.Predict the phenotypic ratio of the F1 individuals. 2.In the second cross, female F1 flies are mated with males with vestigial wings and cinnabar eyes. Predict the phenotypic ratio of the F2 individuals. Homework DUE Tomorrow: Key Ideas and Concept Check #1-3 DUE Thursday: Monohybrid Crosses to turnitin.com DUE Friday: Dihybrid Crosses to turnitin.com DUE Now: 14.3 UNIT 7/8 TEST: March 19 th Inheritance and Regulation

59 Warm-UP: A series of crosses is performed with fruit flies (Drosophila melanogaster) to examine inheritance of the genes vestigial (vg) and cinnabar (cn). The recessive vg allele causes small, malformed wings called vestigial wings. The recessive cn allele causes bright-red eyes called cinnabar eyes. In the first cross, a purebred female with wild-type wings and red eyes is mated with a purebred male with vestigial wings and cinnabar eyes. 1.Predict the phenotypic ratio of the F1 individuals. 2.In the second cross, female F1 flies are mated with males with vestigial wings and cinnabar eyes. Predict the phenotypic ratio of the F2 individuals. 3.The results of the cross from #2 show the following outcome. Individuals of each phenotype are shown in the table. Which of the following is the most likely explanation of the results? a.The two genes are located on two different chromosomes. b.The two genes are sex-linked. c.The two genes are located on mitochondrial DNA. d.The two genes are linked on an autosome. Warm-UP: A series of crosses is performed with fruit flies (Drosophila melanogaster) to examine inheritance of the genes vestigial (vg) and cinnabar (cn). The recessive vg allele causes small, malformed wings called vestigial wings. The recessive cn allele causes bright-red eyes called cinnabar eyes. In the first cross, a purebred female with wild-type wings and red eyes is mated with a purebred male with vestigial wings and cinnabar eyes. 1.Predict the phenotypic ratio of the F1 individuals. 2.In the second cross, female F1 flies are mated with males with vestigial wings and cinnabar eyes. Predict the phenotypic ratio of the F2 individuals. 3.The results of the cross from #2 show the following outcome. Individuals of each phenotype are shown in the table. Which of the following is the most likely explanation of the results? a.The two genes are located on two different chromosomes. b.The two genes are sex-linked. c.The two genes are located on mitochondrial DNA. d.The two genes are linked on an autosome.

60 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes

61 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes

62 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes

63 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes

64 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes

65 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes

66 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes Morgan: experiments with fruit flies Interested in how linkage (when characters are on the same chromosome) affects inheritance of two characters crossed flies that differed in traits of body color and wing size Conclusions: body color and wing size are usually inherited together in specific combinations (parental phenotypes) these genes sometimes assort independently they must linked: on the same chromosome but the linkage is incomplete: cross-over sometimes creates recombinant chromosomes

67 1.Build your diploid cell (an homologous pair for each chromosome) a.Draw a big cell with a nucleus inside. b.DRAW homologous pairs of chromosomes: 1 big blue, 1 big red 1 small blue, 1 small red – Add genes to your chromosome Write an H and an R on big blue, and an h and an r on big red Write a T on small blue, and a t on small red 2.Clone each chromosome (DNA Replication) (making sister chromatids) 3.Nucleus breaks down (erase it). 4.Homologous pairs form a tetrad: crossing over may occur. (note: do not model crossing over for now) 5.Finish meiosis: (see notes for help) 6.Nucleus "grows" around chromosomes. 4 cells made (gametes, which have half the number of chromosomes (haploids) 7.Repeat Steps #1-6, this time at Step 4, include ONE crossover event. Recombination Modeling When you’re confident on the process, show Mr. Jones.

68 When you’re confident on the process, show Mr. Jones. In your notebook: Figure 15.10: Recombination: p.295 At each stage, describe what is happening in 1-2 sentences. DO NOT COPY DRAW with LABELS: cell membrane nucleus chromosome DNA replication cytokinesis sister chromatid crossing over recombinant chromosome independent assortment Meiosis I Meiosis II Recombination Modeling

69 Analysis 1.How does recombination increase the variety of gametes formed? 2.Which types of gametes were more likely? Gametes with recombinant chromosomes or ones without? 3.Recombination is a random process. How might it benefit/hurt the survival of an individual/species? Recombination Modeling

70 Warm-UP: 1.How could you calculate recombination frequency? 2.What would the recombination frequency tell you about the relative position of genes on a chromosome? 3.Genes A, B, and C are on the same chromosome. Testcrosses show that the recombination frequency between A and B is 28% and between A and C is 12%. Can you determine the linear order of these genes? Warm-UP: 1.How could you calculate recombination frequency? 2.What would the recombination frequency tell you about the relative position of genes on a chromosome? 3.Genes A, B, and C are on the same chromosome. Testcrosses show that the recombination frequency between A and B is 28% and between A and C is 12%. Can you determine the linear order of these genes? Homework DUE Tomorrow: Linked and Unlinked Genes DUE Tonight: Monohybrid Crosses to turnitin.com DUE Friday: Dihybrid Crosses to turnitin.com DUE Now: 15.3 UNIT 7/8 TEST: March 19 th Inheritance and Regulation

71 Homework DUE Tomorrow: Linked and Unlinked Genes DUE Tonight: Monohybrid Crosses to turnitin.com DUE Friday: Dihybrid Crosses to turnitin.com DUE Now: 15.3 UNIT 7/8 TEST: March 19 th Inheritance and Regulation Warm-UP: Talk about your Concept Check with your table team. Do you have agreement? Do you have questions?

72 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Sturtevant: Genetic Mapping linkage map: an ordered list of the genetic loci along a particular chromosome based on recombination frequencies map unit one map unit: represents a 1% recombination frequency indicate relative distance and order, not precise locations of genes 50% frequency of recombination is observed for any two genes on different chromosomes the farther apart two genes are, the higher the probability a crossover will occur between them and therefore the higher the recombination frequency genes that are far apart on the same chromosome can have a recombination frequency near 50%. Such genes are physically linked, but genetically unlinked, and behave as if found on different chromosomes Sturtevant: Genetic Mapping linkage map: an ordered list of the genetic loci along a particular chromosome based on recombination frequencies map unit one map unit: represents a 1% recombination frequency indicate relative distance and order, not precise locations of genes 50% frequency of recombination is observed for any two genes on different chromosomes the farther apart two genes are, the higher the probability a crossover will occur between them and therefore the higher the recombination frequency genes that are far apart on the same chromosome can have a recombination frequency near 50%. Such genes are physically linked, but genetically unlinked, and behave as if found on different chromosomes

73 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Sturtevant: Genetic Mapping linkage map: an ordered list of the genetic loci along a particular chromosome based on recombination frequencies map unit one map unit: represents a 1% recombination frequency indicate relative distance and order, not precise locations of genes 50% frequency of recombination is observed for any two genes on different chromosomes the farther apart two genes are, the higher the probability a crossover will occur between them and therefore the higher the recombination frequency genes that are far apart on the same chromosome can have a recombination frequency near 50%. Such genes are physically linked, but genetically unlinked, and behave as if found on different chromosomes Sturtevant: Genetic Mapping linkage map: an ordered list of the genetic loci along a particular chromosome based on recombination frequencies map unit one map unit: represents a 1% recombination frequency indicate relative distance and order, not precise locations of genes 50% frequency of recombination is observed for any two genes on different chromosomes the farther apart two genes are, the higher the probability a crossover will occur between them and therefore the higher the recombination frequency genes that are far apart on the same chromosome can have a recombination frequency near 50%. Such genes are physically linked, but genetically unlinked, and behave as if found on different chromosomes

74 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Abnormal Chromosome Number In nondisjunction, pairs of homologous chromosomes do not separate normally during meiosis As a result, one gamete receives two of the same type of chromosome, and another gamete receives no copy Aneuploidy results from the fertilization of gametes in which nondisjunction occurred Offspring with this condition have an abnormal number of a particular chromosome Abnormal Chromosome Number In nondisjunction, pairs of homologous chromosomes do not separate normally during meiosis As a result, one gamete receives two of the same type of chromosome, and another gamete receives no copy Aneuploidy results from the fertilization of gametes in which nondisjunction occurred Offspring with this condition have an abnormal number of a particular chromosome

75 The chromosomal basis of inheritance provides an understanding of the pattern of transmission of genes from parent to offspring. Abnormal Chromosome Number In nondisjunction, pairs of homologous chromosomes do not separate normally during meiosis As a result, one gamete receives two of the same type of chromosome, and another gamete receives no copy Aneuploidy results from the fertilization of gametes in which nondisjunction occurred Offspring with this condition have an abnormal number of a particular chromosome Abnormal Chromosome Number In nondisjunction, pairs of homologous chromosomes do not separate normally during meiosis As a result, one gamete receives two of the same type of chromosome, and another gamete receives no copy Aneuploidy results from the fertilization of gametes in which nondisjunction occurred Offspring with this condition have an abnormal number of a particular chromosome

76 DUE Tonight: Dihybrid Crosses to turnitin.com DUE Linked vs Unlinked Genes: 15.3 UNIT 7/8 TEST: March 19 th Inheritance and Regulation Warm-UP: What can we learn about inheritance from looking at a pedigree? (use example of the Royal Family of Europe from the early 1900s)

77 Warm-UP: In the following human pedigree, squares represent males, circles represent females, and shaded symbols indicate individuals affected with a disorder. One of the affected males from the third generation has a child with a female who is a carrier. For the pedigree shown, which of the following best expresses the probability that the couple’s first son will be affected with the disorder? (A) 25% (B) 50% (C) 75% (D) 100% DUE Tonight: Dihybrid Crosses to turnitin.com DUE Linked vs Unlinked Genes: 15.3 UNIT 7/8 TEST: March 19 th Inheritance and Regulation

78 Is a widow’s peak a dominant or recessive trait?

79

80 Fig. 14-UN5 George Sandra TomSam Arlene Wilma AnnMichael Carla DanielAlan Tina Christopher

81

82 A heterozygous tall and a homozygous purple flowered plant is crossed with a short and white flowered plant. Predict the offspring. Assume independent assortment #1 P=purple p=white T=tall t=short

83 For a plant with the genotype WwXxYyZz, what is the probability that the plant will produce a gamete with a haploid genotype of Wxyz ? Give your answer as a fraction or as a value between 0 and 1, to four decimal places. #2

84 A completely-plated stickleback from a marine population was mated to a low-plated stickleback from a freshwater population. The resulting F1 hybrids all displayed a completely plated phenotype. When the F1 hybrids were allowed to interbreed, the resulting F2 generation included completely plated offspring and low-plated offspring in an approximate 3:1 ratio. Which of the following conclusions is best supported by the results of the breeding experiments? a.Phenotypic variation in the F2 generation suggests that armor morphology is controlled by many alleles of a single gene. b.The completely-plated phenotype is controlled by a dominant allele of a single gene. c.Armor loss is an acquired characteristic that is affected by one or more environmental factors. d.Patterns of armor plating in stickleback populations are regulated by sex- specific signals. #3

85 If a man with type AB blood marries a woman with type O, what blood types would you expect in their children? What fraction would you expect of each type? #4 I A = Type A I B = Type B i= Type O

86 If a King marries a Queen that is a carrier of hemophilia (sex- linked recessive disease that is historically fatal before adulthood), what is the chance of the Kingdom having an heir to the king’s throne, assuming only one child is born? #5

87 #6 Is an attached earlobe a dominant or recessive trait? Draw the pedigree and fill in the genotypes for each offspring.

88 #6 Is an attached earlobe a dominant or recessive trait? Draw the pedigree and fill in the genotypes for each offspring.

89 #7 Gregor Mendel’s pioneering genetic experiments with pea plants occurred before the discovery of the structure and function of chromosomes. Which of the following observations about inheritance in pea plants could be explained only after the discovery that genes may be linked on a chromosome? a.Pea color and pea shape display independent inheritance patterns. b.Offspring of a given cross show all possible combinations of traits in equal proportions. c.Most offspring of a given cross have a combination of traits that is identical to that of either one parent or the other. d.Recessive phenotypes can skip a generation, showing up only in the parental and F 2 generations.

90 #8 Table I shows the results of breeding experiments to examine the inheritance of flower color (purple versus white) and pod shape (inflated versus constricted). For the crosses recorded in Table I, true-breeding parents were crossed to produce F1 offspring, which were then testcrossed to homozygous recessive individuals. Table II shows the results of computer-simulated crosses to model the inheritance of leaf shape (broad versus narrow) and flower color (purple versus white). Based on the data in Table I, which of the following best explains why there are no individuals with constricted pods in the F 1 generation? a.Inflated pod shape is dominant to constricted pod shape. b.The inflated-pod offspring in the F sub one generation are homozygous. c.Constricted pod shape typically arises from a new mutation in the F 1 generation. d.The constricted-pod offspring are carriers for the inflated pod shape allele.

91 #9 Table I shows the results of breeding experiments to examine the inheritance of flower color (purple versus white) and pod shape (inflated versus constricted). For the crosses recorded in Table I, true-breeding parents were crossed to produce F1 offspring, which were then testcrossed to homozygous recessive individuals. Table II shows the results of computer-simulated crosses to model the inheritance of leaf shape (broad versus narrow) and flower color (purple versus white). In Table I, the ratio of phenotypes in the offspring from the testcross with F 1 plants that had purple flowers and inflated pods suggests that the genes for flower color and pod shape are located a.close together on the same autosome b.on the X chromosome c.on different chromosomes d.on a mitochondrial chromosome

92 #10 Table I shows the results of breeding experiments to examine the inheritance of flower color (purple versus white) and pod shape (inflated versus constricted). For the crosses recorded in Table I, true-breeding parents were crossed to produce F1 offspring, which were then testcrossed to homozygous recessive individuals. Table II shows the results of computer-simulated crosses to model the inheritance of leaf shape (broad versus narrow) and flower color (purple versus white). Which of the following provides the best justification for an assumption that might have been used in the computer simulation (Table II)? a.The broad allele is recessive to the narrow allele because broad leaves appear in every generation. b.The purple allele is dominant to the white allele because all the offspring from the cross of purple-flowered and white-flowered plants had purple flowers. c.The narrow allele is codominant with the purple allele because the purple-flower trait and the narrow-leaf trait segregate together. d.The white allele is dominant to both the broad and narrow alleles because plants with either type of leaf shape can have white flowers.

93 #11 Table I shows the results of breeding experiments to examine the inheritance of flower color (purple versus white) and pod shape (inflated versus constricted). For the crosses recorded in Table I, true-breeding parents were crossed to produce F1 offspring, which were then testcrossed to homozygous recessive individuals. Table II shows the results of computer-simulated crosses to model the inheritance of leaf shape (broad versus narrow) and flower color (purple versus white). In Table II, the F 1 offspring of the cross between broad-leaved, white-flowered plants with narrow-leaved, purple-flowered plants have a phenotype that differs from that of either parent. However, many testcross offspring have the same phenotype as one of the two plants in the parental cross, but relatively few testcross offspring have the same phenotype as the F 1 offspring. Which of the following best explains the observation? a.Recombination between the leaf-shape and flower-color genes resulted in chromosomes carrying a dominant allele of both genes. b.Recombination between the broad and narrow alleles of the leaf-shape gene resulted in chromosomes carrying three different alleles at the same genetic locus. c.Independent assortment of homologous chromosomes resulted in the combinations of alleles present in the parental generation. d.The computer model cannot capture the possible assortments of gametes when multiple genes are considered.


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