Pre AP Biology Genetics Notes Chapter 8 The Origins of Genetics Chapter 8 Section1 Heredity The passing of from to

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1 Name: Pre AP Biology Genetics Notes Chapter 8 The Origins of Genetics Chapter 8 Section1 Heredity The passing of from to Example: Color of of eyes & Date: Period: Gregor Mendel Father of branch of that focuses on Experimented w/ varieties of Why pea plants? traits occur in two forms. There are no forms. Easy to control b/c they are flowers (have both male and parts) Plant is, grows, matures & produces many Some Genetic terms Monohybrid cross True-breeding bred, all will exhibit the traits as P generation generation F 1 of the P F 2 of the F 1 Mendel s Experiments Crossed 2 true plants: one, one F1 generation = Allowed F1 to F2 generation purple, white All of the F1 plants showed only form of the. The contrasting form. In the F2, it F2 generation was a ratio Mendel s Theory Chapter 8 Section 2 Theory of Heredity Before, people thought were a of characteristics of their. Mendel s showed

2 Genetic terms Allele Dominant form of a ( allele) Recessive expressed when dominant is present ( case allele) Homozygous Heterozygous Genotype Phenotype characteristics of an Mendel s Hypotheses 1. For each trait, an indiv. will have copies of the gene (), from each parent. 2. There are versions of (alleles) 3. When alleles are together, one may over the other 4. When are formed, they will only allele for each trait. The Law of Segregation The two alleles for a trait (separate) when gametes are. The Law of Independent Assortment of different genes separate of each other during gamete. Example: Plant does not affect color Studying Heredity Chapter 8 Section 3 Punnett Squares that the of a genetic cross all possible allele Used to predict genetic Setting up a Punnett Square # of = # of of each parent Write the for one parent down the side, and the other alleles across the Fill in the of the Punnett by dropping down and moving them Example Tall (T) is dominant over short (t). If one crosses a homozygous tall plant with a short plant what will the (F1) generation be like? The parents genotype? x Fill in the punnett square to the right using the two parents above

3 Results or plants have the Geneotype Tt Phenotype tall Remember: when the allele is present, it dominates and the dominate trait is. Now cross two of the F 1 generation and write your results in both percent and ratios. Results Genotypes: or or = TT or or = Tt or or = tt Phenotypes: or or = tall or or = short Another way to express : : Monohybrid Cross Involves only trait Dyhybrid Cross Involves 2 traits Example: In garden peas, round (R) is dominant over wrinkled (r) and yellow (Y) is dominant over green (y). Cross a homozygous round, yellow pea with a wrinkled, green pea. Identify parent genotypes: Homozygous round yellow = Wrinkled green = Parents: x Allelic combonations:,,,,,, - 3 -

4 To set up your Punnett square, you multiply the number of alleles of each parent together. Your Punnett Square should look like this: Parent 1: Parent 2: Genotype ratios: Phenotype ratios: Now, cross 2 of the F1 offspring from the previous problem. Parents x Allelic combonations:,,,,,, Now draw your own Punnett square to the right and fill it in while your teacher works it out on the board. Genotype ratios: Phenotype ratios: Test Cross Used to determine what a dominant is Ex: If yellow peas are dominant over green, and plant with a yellow phenotype could be either YY or Yy Cross this individual with a If 100% of offspring is, you know the original plant was If at least offspring produces peas, you know it was

5 Test Cross Example In sweet peas, purple is completely dominant over white. If you have a purple flower, how would you be able to determine if the flower was PP or Pp? Use the example that the teacher is showing on the powerpoint to help guide you. Show your work below. Probability that a specific event will Can be expressed in: Words Decimals - Percentages - Fractions - Probablility in Fractions Prob. = You can to find a of two independent events Inheritance of Traits Autosomal is carried on one of the 22 Sex-linked is carried on either the or the chromosome Most are Pedigree Family that shows how a trait is over several Males = Females = Eldest to go from left to Half shaded shapes = carriers Shaded shapes = Horizontal line =, and a vertical line connects parents with their. Each horizontal row = a, with the most recent generation shown at the

6 Construct a pedigree which traces the recessive trait of Sickle Cell anemia using the following information. Joe & Maria get married and have three children. The birth order of their children from oldest to youngest is Jennifer, Kyle & Nathan. Jennifer marries Doug and has one child Lily. Kyle & Nathan are not married. Maria & Nathan both have sickle cell anemia. Lily is a carrier of the recessive gene. What do you know to be true about Joe & Jennifer? Sex Linked Inheritance Remember the last pair of are the chromosomes. They carry genes as well as the sex of an individual. Sex Linked Traits Carried on the chromosome. Most are. Because have only one X chromosome (remember they are XY), a male who carries a allele on their X have the disorder. A women who is a has another X chromosome that has the allele on it

7 Example Red-green color blindness is inherited as a sex-linked recessive disorder. If a color blind woman marries a man with normal vision, what would be the expected phenotypes of their children with reference to color blindness? Women s genotype: Man s genotype: The Punnett Square for these two people would look like (Try to draw a Punnett square below and fill it in using the parents above.) What would their children be like? All the girls would be, but. All the boys would be. Complex Patterns of Heredity Chapter 8 Section 4 Polygenic Traits genes the trait Examples: Incomplete Dominance When an displays an trait Examples: Some colors hair - 7 -

8 Work out this problem. In certain flowering plants, red (R) is not completely dominant over white (r). When crossed, the heterozygous offspring is pink. Red will results with 2 red alleles and white will result with 2 white alleles. What would the F1 offspring be if you crossed a red and a white flower together? Red flower = White flower = State the genotypes of your parents: Parent 1: Parent 2: You will cross Parent 1 with Parent 2: x Now, draw your Punnett square and fill it in appropriately. What are the genotype ratios: What are the phenotype ratios: Now, cross two of the F1 offspring: Parent Genotypes: x Now, draw your Punnett square and fill it in appropriately. What are the genotype ratios: What are the phenotype ratios: Codominance Two alleles results in traits being displayed Example: cattle have can have red hair white hair. When dominant alleles are present those cattle would have both red white hair. Multiple Alleles Genes w/ or more Ex: human I A I A & I A i = Blood type I B I B & I B i = Blood type I A I B = Blood type ii Blood type Example problem A man with blood type of O, marries a woman with type A blood. They have a child that is blood type O. What is the genotype of the woman? (Work it out as the teacher works it out on the board.) - 8 -

9 Environmental Influences Sometimes factors can different without changing the Genetic Disorders Occurs when genes are or are copied into proteins. Many are carried on the allele meaning two parents can have an abnormal. Treating Genetic Disorders Most are Some can be treated early Gene Therapy Allows to defective genes with ones - 9 -