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GENETICS Ch. 11. Gregor Mendel Genetics is the study of heredity. Genetics is the study of heredity. Gregor Mendel (1860s) discovered the fundamental.

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Presentation on theme: "GENETICS Ch. 11. Gregor Mendel Genetics is the study of heredity. Genetics is the study of heredity. Gregor Mendel (1860s) discovered the fundamental."— Presentation transcript:

1 GENETICS Ch. 11

2 Gregor Mendel Genetics is the study of heredity. Genetics is the study of heredity. Gregor Mendel (1860s) discovered the fundamental principles of genetics by breeding garden peas. Gregor Mendel (1860s) discovered the fundamental principles of genetics by breeding garden peas.

3 2. Mendel cross- pollinated pea plants He cut away the male parts of one flower, then dusted it with pollen from another He cut away the male parts of one flower, then dusted it with pollen from another

4 3. What did Mendel conclude? He concluded that factors are passed from one generation to the next. He concluded that factors are passed from one generation to the next.

5 4. The Principle of Dominance Alleles Alleles 1.Alternative forms of genes. 2.Units that determine heritable traits. Paternal Maternal eye color locus B = brown eyes eye color locus b = blue eyes The Principle of Dominance – some alleles are dominant and other are recessive.

6 5. Dominant and Recessive alleles Dominant alleles – upper-case a. homozygous dominant (BB – Brown eyes) Recessive alleles – lower case a. homozygous recessive (bb – blue eyes) b. Heterozygous (Bb – Brown eyes)

7 Phenotype vs. Genotype Outward appearance Outward appearance Physical characteristics Physical characteristics Examples: Examples: 1.Brown eyes 2.blue eyes Arrangement of genes that produces the phenotype Arrangement of genes that produces the phenotype Example: Example: 1.TT, Tt 2. tt

8 6. Segregation Alleles separate during meiosis

9 7. Recessive traits show up about 1/4 th of the time. Because there is only a 25% chance that two recessive alleles will be paired together. Because there is only a 25% chance that two recessive alleles will be paired together.

10 9. Punnett square A Punnett square is used to show the possible combinations of gametes. A Punnett square is used to show the possible combinations of gametes. Monohybrid Cross Monohybrid Cross

11 Monohybrid Cross Example:Cross between two heterozygotes for brown eyes (Bb) Example:Cross between two heterozygotes for brown eyes (Bb) BB = brown eyes Bb = brown eyes bb = blue eyes B b Bb Bb x Bb male gametes female gametes

12 Monohybrid Cross BB Bb bbB b Bb Bb x Bb 1/4 = BB - brown eyed 1/2 = Bb - brown eyed 1/4 = bb - blue eyed 1:2:1 genotype 3:1 phenotype

13 Dihybrid Cross

14 RYRyrYry RYRy rY ry

15 RRYY RRYy RrYY RrYy RRYy RRyy RrYy Rryy RrYY RrYy rrYY rrYy RrYy Rryy rrYy rryy Round/Yellow: 9 Round/green: 3 wrinkled/Yellow: 3 wrinkled/green: 1 9:3:3:1 phenotypic ratio RYRyrYryRY Ry rY ry

16 Dihybrid Cross Example:cross between round and yellow heterozygous pea seeds. Example:cross between round and yellow heterozygous pea seeds. R= round r= wrinkled Y= yellow y= green RY Ry rY ry RY Ry rY ry RY Ry rY ry x RY Ry rY ry possible gametes produced RrYyRrYy RrYy x RrYy

17 10. Independent Assortment Bb diploid (2n) B b meiosis I B B b b sperm haploid (n) meiosis II Chromosomes separate independently of eachother Chromosomes separate independently of eachother Bb Ff BFBF BfBf bfbf B F Bb Ff Bb Ff This means all gametes will be different!

18 Independent Assortment Genes for different traits can segretate independently during the formation of gametes without influencing eachother Genes for different traits can segretate independently during the formation of gametes without influencing eachother Question: How many gametes will be produced for the following allele arrangements? Question: How many gametes will be produced for the following allele arrangements? Remember: 2 n (n = # of heterozygotes) Remember: 2 n (n = # of heterozygotes) 1.RrYy 2.AaBbCCDd 3.MmNnOoPPQQRrssTtQq

19 Answer: 1. RrYy: 2 n = 2 2 = 4 gametes RY Ry rY ry 2. AaBbCCDd: 2 n = 2 3 = 8 gametes ABCD ABCd AbCD AbCd aBCD aBCd abCD abCD 3. MmNnOoPPQQRrssTtQq: 2 n = 2 6 = 64 gametes

20 11. Incomplete Dominance One allele is not completely dominant over another One allele is not completely dominant over another Rr r r RR All Rr = pink (heterozygous pink) produces the F 1 generation

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22 11. Codominance Both alleles are expressed Both alleles are expressed Example: blood Example: blood 1.type A= I A I A or I A i 2.type B= I B I B or I B i 3.type AB= I A I B 4.type O= ii Black cow + white cow = spotted cow

23 12. Which shows more genetic variation. (more combos?) Male CC with female Cc Male CC with female Cc Male cc with female Cc Male cc with female Cc C c cc C c CC

24 Genetic Engineering

25 Gene Therapy

26 Is cloning a possibility? Is it right to use cloning to create an entirely new human being? Is it right to use cloning to create an entirely new human being? Is it ethical to create an embryonic copy of John Doe to supply cells to keep John alive? Is it ethical to create an embryonic copy of John Doe to supply cells to keep John alive? Does a multicellular ball of tissue -- an embryo -- have the same rights and status as a human being? Does a multicellular ball of tissue -- an embryo -- have the same rights and status as a human being?

27 How does Mendels principles apply to organisms The basic principals can be applied to humans as well as any other living organism. The basic principals can be applied to humans as well as any other living organism.

28 And now its time for…. Spongebob Genetics!!!!! Spongebob Genetics!!!!!


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