NonMendelian Genetics Not simple Dominant and Recessive Pedigree

Non-Mendelian Genetics Not simple Dominant and Recessive

Pedigree § Pedigree = map of inheritance of genetic traits from generation to generation

Symbols on a Pedigree § § § Circle = Female Square = Male Shaded = Affected Unshaded = Unaffected Adjoining line = Married/Mating Connected by an adjoining line = Offspring Roman Numeral = Generation

Recessive Heredity § Caused by recessive alleles § Attached earlobes, Cystic fibrosis (defective protein leads to excessive mucus production in lungs), Albinism § Individual will only display the recessive phenotype if its genotype is homozygous recessive (aa)

Dominant Heredity § Caused by dominant allele § Freckles, Widow’s peak, Hitchhickers thumb, Huntington’s disease (brain degeneration, doesn’t appear until later in age), immunity to poison ivy § Individual will display the dominant phenotype if its genotype is heterozygous(Aa) or homozygous dominant(AA)

Textbook pg. 310 Fig. 12. 2 With your lab partner answer the following questions on a separate sheet of paper. 1. How many generations are shown? 2. How many offspring did I-1 and I-2 have? 3. How many boys did III-3 and III-4 have? 4. How many girls did II-1 and II-2 have? 5. What kind of trait (dominant or recessive) is being passed down? 6. What genotypes must I-1 and I-2 be in order to have a child with this trait? 7. What is the probability that they would have this type of child? Show a Punnett square

When Heredity Follows Different Rules Chapter 12, Section 2

Incomplete Dominance § Incomplete Dominance = phenotype of a heterozygote is in between the dominant & recessive phenotypes, appearance of a third phenotype. § No Longer Upper and Lowercase letters A or a Flowers known as Snapdragons come in 3 colors but have 2 alleles, R and R’ § R’R’ = White § R’R or RR’ = Pink § RR = Red

Practice Problems Cross the following snapdragons and give the genotype and phenotype ratios. Red x White – Phenotypic Ratio White : Pink : Red Genotypic Ratio R’R’: R’R : RR Pink x Pink – Phenotypic Ratio White : Pink : Red Genotypic Ratio R’R’: R’R : RR

Text pg. 316 Figure 12. 7 § Red x White = all pink § Pink x Pink = 1 Red: 2 Pink: 1 White

Genetics Review § Mendelian Genetics – Simple Dominant & Recessive Traits (Tall TT or Tt or short tt) § Incomplete Dominance – 3 phenotypes (FF = red, FF’ = pink, F’F’ = white) § Pedigree – Map to show traits are passed from parent to offspring (not shaded – doesn’t have trait, half shaded – carrier, shaded – has trait

Codominance Both alleles for a gene are expressed in a heterozygous individual • Black Feathers FBFB = Black Feathers • White Feathers FW FW = White • When the 2 alleles are combined a chicken with both black and white feathers is created. • Erminette chickens FBFW = Black & White • Neither allele is dominant or recessive

Codominance Practice Problems § Cross a chicken that is homozygous for the black alleles with a chicken that is homozygous for the white alleles. § What color feathers did the offspring have? § Cross 2 chickens from the F 1 generation to make the F 2 generation? § What color feathers did the offspring have?

Blood Types § BLOOD TYPE. ppt

Genetic Testing § Genetic Tests are now available that can tell you the probability that an individual will have a certain disorder. Write Yes or No on the whiteboard to answer the following questions. § Would you want to be tested? § Would you have a significant other tested? § Would you have your child tested? § Would you agree to be tested if you are an employee? § Would you as an employer require job applicants to take a test?

Sex Determination & Sexlinked Inheritance § Combination of sex chromosomes (X and Y) determine an individual’s gender § Males XY, X chromosome comes from mom & Y chromosome comes from dad § Females XX, both mom & dad give an X chromosome § Sex-linked Traits = traits controlled by genes on sex chromosomes

Examples of X Linked Traits § § § Red-Green colorblindness Hemophilia (blood doesn’t clot properly) Duchenne Muscular Distrophy (muscular degeneration leading to eventual paralysis)

§ Most of sex-linked traits are found on genes on the X chromosome (X-linked trait) because it is larger than the Y chromosome § X-linked traits display more in males because they only have 1 X chromosome, whereas females get 2 X chromosomes so they can be carriers of the trait but not display the phenotype

Color Blindness - Recessive Trait B = Normal b = color blind § Males XBY = Normal Xb. Y = Color Blind § Females XBXB = Normal XBXb = Carrier (Normal) Xb. Xb = Color Blind Can males be carriers for color blindness? Why or why not?

Sex Linked Crosses § Cross a color blind male with a carrier female? § What is the probability you will get a color blind child? § What is the probability you will get a color blind male? Only look at males. § What is the probability you will get a carrier female? Only look at the females

Polygenic Inheritance § Characteristics that are influenced by several genes