2. What is Genetics? Genetics is the study of heredity. Heredity is how traits are passes down from generation to generation. “Father of Genetics”. He studied the way characteristics are passed on in pea plants in the 1800’s. Gregor Mendel

3. Mendel’s Discovery  Mendel discovered that a pea plant’s characteristics such as height, seed color and pod color are determined by an inheritance factor.  These inheritance factors where later called genes. Genes are a unit of heredity. They contain the instructions for a trait.  A trait is a characteristic (color, height) coded for by two or more genes.

4. A gene can be defined as a region of DNA that controls a hereditary characteristic. Genes can be as short as 1000 base pairs or as long as several hundred thousand base pairs. It can even be carried by more than one chromosome. The estimate for the number of genes in humans has decreased as our knowledge has increased. As of 2001, humans are thought to have between 30,000 and 40,000 genes. http://www.accessexcellence.org/RC/VL/GG/genes.html Chromosomes Genes DNA

5. DNA strand chromosomes genes Cell nucleus containing 23 pairs of chromosomes DNA makes up genes. Genes make up chromosomes. There are 23 pairs (46 total) chromosomes in each non-sex cell for humans. 23 chromosomes in sex cells.

6. http://www.accessexcellence.org/RC/VL/GG/human.html Females have XX chromosomes. Males have XY chromosomes. Genetic disorders: Tay-Sachs: Caused by a gene mutation on chromosome 15 Down Syndrome: An extra copy of chromosome 21 is present. Look up other genetic disorders. genetic disordersgenetic disorders

7. Allele: 2 forms of a gene Dominant: The gene that covers up the effect of the other one. The gene that covers up the effect of the other one. Use a capital letter. Use a capital letter. Mendel’s Experiment: Green seed color (G) Recessive: The effect of the gene is hidden (unless two are present). The effect of the gene is hidden (unless two are present). Use a lower case letter. Use a lower case letter. Mendel’s Experiment: Yellow seed color (g)

8. When we write genes we use one letter (G or g, R or r, etc.) Traits or characteristics are determined by one or more pair of genes. Half of your genes come from your mother and half of your genes come from your father. Homozygous or purebred: Both genes are the same. Mendel’s Experiment: Green seed color (GG), Yellow seed color (gg) homozygous dominant, homozygous recessive homozygous dominant, homozygous recessive Heterozygous or hybrid: Both genes are different. Mendel’s Experiment: Green seed color (Gg)

9. Traits are ways to describe living things. We are going to focus on human traits during genetics. Traits that we may discuss include: hair color, eye color, blood type. Phenotype: What the organism looks like. Mendel’s Experiment: Green seed color, Yellow seed color Genotype: The genetic make-up of a trait. Mendel’s Experiment: GG, Gg or gg

10. Practice Problem Mendel also studied the heights of pea plants during his experiments. He determined that tall pea plants were dominant over short pea plants. Step 1: Create a key. Pick a letter to represent genes. Dominant = Tall (T) Recessive = short (t) Use the key to help you answer the following questions: 1. Determine the phenotype of a plant that is Tt. 2. Determine the genotype of a homozygous small plant. 3. Would a heterozygous plant show the dominant or recessive trait?

11. Dominant = Tall (T) Recessive = short (t) 1.Determine the phenotype of a plant that is Tt. Phenotype means what it looks like. It will be tall because it has one dominant gene (T). 2. Determine the genotype of a homozygous small plant. Genotype means genetic make-up. Homozygous means the same and small is recessive (small letter).The answer is tt. 3. Would a heterozygous plant show the dominant or recessive trait? Heterozygous means different. (Tt) The answer is dominant because there is at least one big T. To show recessive you have to have two small t’s.

12. Mitosis: Occurs in body cells. Occurs in body cells. One cell divides into two. One cell divides into two. Both cells have the same genetic material as the parent cell. Both cells have the same genetic material as the parent cell. Four chromosomes Four chromosomes copied Four chromosomes go into each cell during division Four chromosomes in each identical cell

13. Meiosis: Occurs in sex cells (egg and sperm). Occurs in sex cells (egg and sperm). One cell divides into four. One cell divides into four. The four daughter cells have ½ the genetic material as the parent cell. The four daughter cells have ½ the genetic material as the parent cell. Stage 1: Stage 2:

14. 1. Brown hair is dominant over blonde. A. Create a key for the traits. A. Create a key for the traits. B. What would the genotype for a blonde be? B. What would the genotype for a blonde be? C. What would the phenotype be for a person that is C. What would the phenotype be for a person that isheterozygous? 2. Freckles is dominant over non-freckles. Mom is purebred for freckles. Dad is heterozygous for freckles. A. Create a key for the traits. A. Create a key for the traits. B. Determine the genotypes for Mom and Dad. B. Determine the genotypes for Mom and Dad. C. Could any of their children NOT have freckles? Explain your answer. C. Could any of their children NOT have freckles? Explain your answer. Vocabulary Practice Problems

15. 1A. Key: B = brown = dominant b = blonde = recessive b = blonde = recessive 1B. Blonde is recessive. “bb” 1C. Heterozygous means different. Phenotype means what it looks like. “Brown hair” 2A. Key: F = freckles = dominant f = non-freckles = recessive f = non-freckles = recessive 2B. Mom = FFDad = Ff 2C. There is no possibility that any of their children could not have freckles. Mom has two big F genes, which means she will always give her children a F. Therefore all of the children will have freckles. You need two little f’s for non-freckles.

16. Pedigree Chart Follows the passing of a trait from generation to generation. Looks like a family tree. = male = female Shaded shape means that the recessive trait is expressed. Half shaded shape means that they are a carrier of the trait. Carriers have one gene but do not express or show the trait.

17. marriage parents children Generation 1 Generation 2 Oldest child to the left Youngest child to the right Number of rows = number of generations Count from the top to the bottom

18. 1 3 6 9 8 10 12 5 11 7 2 4 nn N N N N NNnn nn n _ N = normal vision = dominant n = nearsighted = recessive Shaded = recessive trait Page 6 in Packet

19. D = dimples d = non-dimples 21 1514 13 9 75 34 6 810 11 12 Dd dd Dd dd DdddDd ddDd dd Dd More Pedigree Practice

20. Punnett Squares Determine the probability that offspring will or will not have a given trait. Think back to Mendel’s pea experiment. We looked at green seeds and yellow seeds. If both plants are homozygous, what are their genotypes? Think back to Mendel’s pea experiment. We looked at green seeds and yellow seeds. If both plants are homozygous, what are their genotypes? Plant 1 (green) = GG Plant 2 (yellow) = gg Identify the genes that are present in each plants’ sex cells. GGgg GGgg

21. We are now going to determine the possible genotypes and phenotypes of the offspring using a Punnett Square. GG x gg g G g G GgGgGgGg GgGgGgGg GgGgGgGg GgGgGgGg Genotype Phenotype gg = Gg = GG = 0/4 = 0% 4/4 = 100% 0/4 = 0% Green = 0/4 = 0% 4/4 = 100% Yellow =

22. Determine the genotype and phenotype probabilities for a cross between two heterozygous plants from the previous problem. Determine the genotype and phenotype probabilities for a cross between two heterozygous plants from the previous problem. Parents = Gg X Gg Gg G GG GgGgGgGg g GgGgGgGggg Genotype Phenotype gg = Gg =Gg =Gg =Gg = GG = 1/4 = 25% 2/4 = 50% 1/4 = 25% Green = Yellow = 3/4 = 75% 1/4 = 25%

23. Determine the genotype and phenotype probabilities for a cross between a heterozygous plant and a short plant. The trait we are studying is plant height. Tall is dominant over short. Tt tTttt t Tt tt Parents = Tt X tt T = tall = dominant t = short = recessive Genotype Phenotype Tall = Short = 2/4 = 50% TT = Tt = tt = 2/4 = 50% 0/4 = 0%

24. Punnett Square Practice Problems 1. 1. Normal skin pigment is dominant over albino. Show a cross of an albino man with a heterozygous normal woman. 2. 2. Brown eyes are dominant over blue eyes. Using a Punnett Square, determine the probability that the offspring will be homozygous recessive if both parents are heterozygous dominant. 3. 3. Determine the genotypes for the individuals in the pedigree chart below. Widow’s peak is dominant over non-peak. a. a.Make a key b. b.Determine genotypes c. c.Determine number of generations d. d.What is the dominant trait? e. e.How many males have peak? f. f.How many marriages?

25. 1. Key:N = normal = dominant n = albino = recessive Parents: Male = nnFemale = Nn n n N Nn Nn nnnn n Genotype Phenotype normal = albino = 2/4 = 50% NN= Nn = nn = 2/4 = 50% 2/4 = 50% 0/4 = 0%

26. 2. Key:B = brown = dominant b = blue = recessive Parents: Male = BbFemale = Bb B b B Bb BB bbBb b Genotype Phenotype brown = blue = 3/4 = 75% 1/4 = 25% BB= Bb = bb = 1/4 = 25% 1/4 = 25% 2/4 = 50% 2/4 = 50% 1/4 = 25%

27. Key: W= widow’s peak = dominant w = non- peak = recessive c) 4 generations d) Having the widow’s peak is dominant. e) 2 males have a widow’s peak. f) 4 marriages IIV III II Ww ww Ww WwWw wwWw W_wwW_W_ Ww Ww W_W_

28. Sex-linked traits Sex-linked traits are caused by genes found on the X chromosome. Sex-linked traits are caused by genes found on the X chromosome. Sex-linked traits are recessive. Sex-linked traits are recessive. Fewer females are afflicted with these traits because they have two X chromosomes and the other is usually normal. Fewer females are afflicted with these traits because they have two X chromosomes and the other is usually normal. Males only have one X chromosome, so when they inherit the sex-linked gene, they display the trait. Males only have one X chromosome, so when they inherit the sex-linked gene, they display the trait. Examples: color-blindness, hemophilia Examples: color-blindness, hemophilia XXXX-X-X-XYX-Y NormalfemaleCarrierfemaleAfflictedfemaleNormalmaleAfflictedmale

29. Sex-linked traits practice problems 1. A man normal for blood clotting marries a woman who is a carrier for hemophilia. What are the chances they will have a child with hemophilia? Use a Punnett Square to prove your answer. 2. What is the probability that a woman with normal vision who marries a color-blind man will have a color-blind child? 3. A man with normal vision and a woman with normal vision have three sons. Two of the sons have normal vision and one of them is color-blind. What are the probable genotypes of the parents?

30. Intermediate Inheritance Not all traits are either dominant or recessive. Not all traits are either dominant or recessive. For some traits, heterozygous individuals are different than both homozygous parents. For some traits, heterozygous individuals are different than both homozygous parents. Codominance Incomplete Dominance Both alleles are expressed in heterozygous offspring Both alleles are expressed in heterozygous offspring Both alleles are dominant Both alleles are dominant Both are different capital letters Both are different capital letters Both alleles are blended in heterozygous offspring Both alleles are blended in heterozygous offspring Both are different capital lettersBoth are different capital letters Red coat = C R C R White coat = C W C W Roan coat = C R C W (both red and white are seen) Red flowers = RR White flowers = WW Pink flowers = RW

31. Multiple Alleles: When there are more than 2 (multiple) alleles for a trait. When there are more than 2 (multiple) alleles for a trait. Examples: Human blood groups have 3 alleles. (A, B, O) Examples: Human blood groups have 3 alleles. (A, B, O) A and B are both dominant, O is recessive The possible combinations of these blood alleles are: The possible combinations of these blood alleles are: PhenotypeGenotype(s) A I A I A, I A i B I B I B, I B i AB IA IBIA IBIA IBIA IB Oii

32. Dihybrid Crosses Study two traits at the same time. Determine the outcome for both traits together. A pure tall plant with blue flowers is mated with a short plant with white flowers. Determine the genotypes and phenotypes of the offspring. Tall and blue flowers are both dominant traits. T = t = B = b = tall short blue white Parents: TTBBXttbb TTBB ttbb TB tb

33. TB tb TtBb GenotypePhenotype TtBb =100% Tall and blue =100%

34. Now mate two of the offspring to determine the possible genotypes and phenotypes. TtBb X TtBb TB TbtB tb TB Tb tB tb TBTb tb tB Tb TB tbtB TTBBTTBbTtBBTtBb TTBbTTbbTtBbTtbb TtBBTtBbttBBttBb TtBbTtbbttBbttbb Genotype Phenotype ttbb ttBb TtBb Ttbb ttBB TtBB TTBB TTbb TTBb Tall, blue = 9/16 (56.25%) Short, blue = 3/16 (18.75%) Tall, white = 3/16 (18.75%) Short, white = 1/16 (6.25%) = 1/16 = 6.25% = 2/16 = 12.5% = 4/16 = 25% = 2/16 =12.5% = 1/16 = 6.25% = 2/16 = 12.5% = 1/16 = 6.25% = 2/16 = 12.5%

35. 1. When a mouse with black fur is crossed with a mouse with white fur, all F 1 generation offspring have gray fur. What are the probable genotypes and phenotypes for the F 2 generation? Is this an example of codominance or incomplete dominance? 2.What would the possible genotypes and phenotypes be for a cross between a roan-coated cow (C R C W ) and a red-coated cow (C R C R )? Is this an example of codominance or incomplete dominance? Incomplete dominance & Codominance

36. 1. A couple preparing for marriage have their blood typed. They are both AB. They are curious about the possible blood types their children might have. What are the possible phenotypes of their children? 2. A type A person marries a type A person. Their firstborn has type O blood. What are the genotypes of the parents and the child? 3.A wealthy elderly couple die together in an accident. Soon a man shows up to claim their fortune, claiming he is their long lost son. Other relatives dispute the claim. Hospital records show that the deceased couple were blood types AB and O. The person claiming to be their son is type O. Do you think this man is an impostor? Explain why. Blood Type Problems