Ch. 11 Notes - Genetics

I. Who was Gregor Mendel? A. Gregor Mendel - Austrian monk who studied how traits are inherited; known as the “Father of Genetics” 1. Genetics - branch of biology that studies heredity a. Heredity - passing on of traits from parent to offspring

I. Who was Gregor Mendel? B. Mendel’s Experiments 1. Studied/Researched on pea plants a. They have many traits such as flower color (purple or white), peas (round or wrinkled), pea color (yellow or green) and height (tall or short).

I. Who was Gregor Mendel? Short pea plant Tall pea plant All tall pea plants 3 tall: 1 short P1 F1 F2 b. Mendel bred a tall pea plant with a short plant (P generation). c. The offspring in the 1st generation (F1 generation) were all tall.

I. Who was Gregor Mendel? d. Then, he bred two of the F1 plants. Short pea plant Tall pea plant All tall pea plants 3 tall: 1 short P1 F1 F2 d. Then, he bred two of the F1 plants. e. The offspring in the 2nd generation (F2 generation) were 75% tall and 25% short. f. The short trait disappeared in the 1st generation and reappeared in the 2nd generation.

I. Who was Gregor Mendel? Short pea plant Tall pea plant All tall pea plants 3 tall: 1 short P1 F1 F2 2. Mendel discovered that each trait is controlled by alleles. a. Alleles: forms/versions of the same gene Each person has TWO alleles for each gene; 1 from mother and 1 from father. Ex: T = the allele for tall; t = the allele for short

I. Who was Gregor Mendel? Some alleles are dominant and recessive Dominant - a trait that is always expressed (seen) in an individual if the allele is present (capital letter) Ex: T = tall allele Recessive - a trait that is hidden by the dominant allele; expressed only when two copies of the recessive allele are inherited (lowercase letter) Ex: t = short allele

I. Who was Gregor Mendel? Individuals can be described by their genotype and phenotype Genotype - genetic makeup (letters); alleles present in an individual Ex: TT, Tt, tt Type of Genotypes: Homozygous - two of the SAME alleles for a trait Ex: TT or tt Heterozygous (hybrid) - two DIFFERENT alleles for a trait Ex: Tt

I. Who was Gregor Mendel? TT, Tt=tall tt=short Phenotype - physical appearance; what traits are expressed in the individual Ex: tall or short plants TT, Tt=tall tt=short

II. Punnett Squares/Test Crosses A. Punnett Square/Test Cross - a tool used to predict the alleles/traits present in offspring 1. When parents produce gametes (sperm or eggs), their genes separate to produce haploid cells a. Each gamete contains ONE allele Homozygous Tall Dad Heterozygous Tall Dad Homozygous Short Dad T T T t t t

II. Punnett Squares/Test Crosses B. How to Solve a Monohybrid Cross 1. Determine the genotypes (letters) of the parents. 2. Set up the punnett square with one parent on top and one parent on the side. 3. Fill out the Punnett square boxes (Look up and over to the left to fill them in). 4. Analyze the probability (likelihood) that the offspring would possess each specific trait.

II. Punnett Squares/Test Crosses C. Practice Y = yellow pea color; y = green pea color 1. Cross two heterozygous pea plants. Parent 1 Genotype __________ Parent 2 Genotype __________ What is the chance of the offspring having yellow pea color? Genotypic Ratio: YY : Yy : yy Phenotypic Ratio: yellow : green

II. Punnett Squares/Test Crosses Y = yellow pea color; y = green pea color 2. Cross a homozygous recessive pea plant with a heterozygous pea plant. Parent 1 Genotype __________ Parent 2 Genotype __________ What is the chance of the offspring having yellow pea color? Genotypic Ratio: YY : Yy : yy Phenotypic Ratio: yellow : green

II. Punnett Squares/Test Crosses Y = yellow pea color; y = green pea color 3. Cross a homozygous recessive pea plant with a homozygous dominant pea plant. Parent 1 Genotype __________ Parent 2 Genotype __________ What is the chance of the offspring having yellow pea color? Genotypic Ratio: YY : Yy : yy Phenotypic Ratio: yellow : green

II. Punnett Squares/Test Crosses D. How to Solve a Dihybrid Cross 1. Determine parent genotypes (letters). 2. Determine gamete combinations from mom and dad. (FOIL method from math class - Use arrows!) 3. Write the gametes from mom on 1 side of the square and dad on the other side. 4. Fill in the boxes in the punnett square (look up and to the left). 5. Analyze the probability (likelihood) that the offspring would possess the specific traits.

II. Punnett Squares/Test Crosses PRACTICE: R = round peas, r = wrinkled peas Y = yellow pea color; y = green pea color Cross two heterozygous round yellow pea plants. Parent 1 Genotype _____ Parent 2 Genotype _____ Parent Gamete Possibilities: FOIL Parent #1 Gametes: RY, Ry, rY, ry Parent #2 Gametes:  RY, Ry, rY, ry

What is the chance of the offspring having round and yellow peas? Ry RY rY ry RY Ry rY ry

III. Special Inheritance A. Autosomes - 22 pairs of body chromosomes in a human 22 Autosomes Sex chromosomes

III. Special Inheritance B. Sex chromosomes - 1 pair of chromosomes in a human; the last pair in a karyotype a. Ex. XX-female XY- male 22 Autosomes Sex chromosomes

III. Special Inheritance Show a punnett square crossing male and female sex chromosomes. d. Every time a male and female have a baby, what is the chance of them having a son? A daughter? e. If a female has 5 sons in a row, what is the chance of her having another son? A daughter? f. Which parent determines the sex of the child? WHY?

III. Special Inheritance C. Sex-Linked Traits - traits located on the sex chromosomes (usually the X chromosome) a. Dad gives X chromosome to daughters and Y chromosome to sons b. Mom gives X chromosome to daughters and sons If a male inherits a sex-linked trait, which parent(s) gave him the trait? MOM If a female inherits a sex-linked trait, which parent(s) gave her the trait? MOM OR DAD Who (males or females) is most likely to inherit a sex-linked trait? WHY? Males – they only need to inherit ONE X chromosome

III. Special Inheritance c. Examples in humans Male pattern baldness Red/green colorblindness Hemophilia (problems with blood clotting) Muscular Dystrophy (muscle weakness, loss of muscle tissue)

III. Special Inheritance d. Other Examples Eye color in Drosophila (fruit flies) R = Red eye Color; r = white eye color Cross white eyed male (XrY) with red eyed female (XRXR) What percentage of offspring are likely to have red eyes? What percentage of male offspring are likely to have red eyes? What percentage of female offspring are likely to have red eyes?

III. Special Inheritance Examples Eye color in Drosophila (fruit flies) R = Red eye Color; r = white eye color Cross white eyed male (XrY) & heterozygous red eyed female (XRXr) What percentage of offspring are likely to have red eyes? What percentage of male offspring are likely to have red eyes? What percentage of female offspring are likely to have red eyes?

IV. Not all traits are controlled by simple dominant and recessive alleles! A. Incomplete Dominance - heterozygous individuals display an intermediate (blending) phenotype of the two homozygous individuals 1. Examples in humans Hair texture SS = straight CC = curly SC = wavy Tay Sachs Disease (inability to produce enzyme that breaks down lipids) EE = produces enzyme NN = does not produce enzyme EN = produces half amount of enzyme

IV. Not all traits are controlled by simple dominant and recessive alleles! 2. Other Examples Flower color in snapdragons RR = Red, WW = white, RW = pink Cross a red flower with a white flower. Parent 1 Genotype ______ Parent 2 Genotype _____ What is the chance of producing a pink flower? Genotypic Ratio: RR : RW : WW Phenotypic Ratio: red: pink: white

Cross a pink flower with a pink flower. III. Not all traits are controlled by simple dominant and recessive alleles! Cross a pink flower with a pink flower. Parent 1 Genotype _____ Parent 2 Genotype _____ What is the chance of producing a white flower? Genotypic Ratio: RR : RW : WW Phenotypic Ratio: red: pink: white

III. Not all traits are controlled by simple dominant and recessive alleles! B. Co-dominance - heterozygous individuals display BOTH traits of the two homozygous individuals 1. Examples in humans Sickle Cell Anemia (abnormally shaped red blood cells) NN = normal shaped cells SS = sickle shaped cells NS = normal and sickled shaped cells Blood Type Type A Type B Type AB

***** Special Inheritance ***** Hemoglobin—protein that carries oxygen in blood, makes blood red In homozygous recessive individuals—hemoglobin is defective and makes blood cells sickle (half moon) shaped These blood cells—cause slow blood flow, block small vessels, tissue damage and pain In heterozygous individuals – both normal and sickled hemoglobin are produced They produce enough normal hemoglobin that they do not have serious health problems

Genotypic Ratio: BB: BW : WW Phenotypic Ratio: IV. Not all traits are controlled by simple dominant and recessive alleles! 2. Other Examples Coat color in chickens BB = black WW = white BW = black AND white speckled Cross a black rooster with a white chicken. Parent 1 Genotype _____ Parent 2 Genotype _____ What is the chance of producing black and white chicks? Genotypic Ratio: BB: BW : WW Phenotypic Ratio: black: black/white: white

IV. Not all traits are controlled by simple dominant and recessive alleles! Complete the last cross on your own. Be ready to discuss.

V. Blood Type (codominance in humans) A. An example of multiple alleles – more than one allele controls the trait B. It is determined by the presence or absence of proteins (chains of amino acids) on the surface of red blood cells a. Mixing incompatible blood types can cause blood clots, which can result in death

V. Blood Type (codominance in humans) Human Blood Types Phenotype Genotype Blood cell surface molecules (antigens) Type A IAIA or IAi A antigens Type B IBIB or IBi B antigens Type AB IAIB A and B antigens Type O ii No antigens

V. Blood Type (codominance in humans)

V. Blood Type (codominance in humans) C. Alleles IA and IB – are co-dominant to each other D. Allele i –is recessive to both IA and IB a. Type O blood — universal donor Has no proteins on the blood cells so any blood type can receive it b. Type AB blood — universal acceptor Has both proteins on blood cells so this blood type can receive any blood

V. Blood Type (codominance in humans) E. Cross parent with A ( IAi) blood with a parent with B blood (IBi). Genotypic ratio 0 IA IA : 1 IA i : 0 IB IB : 1 IB i : 1 IA IB : 1 ii IA i IBi IAIB IB i IAi ii Phenotypic ratio (blood type)— 1 type AB : 1 type A : 1 type B : 1 type O

VI. Rh Factor – describe the presence or absence of another protein on blood cells. A. Rh Positive = have proteins a. Genotypes: Rh+/Rh+ or Rh+/Rh- B. Rh Negative = no proteins b. Genotype: Rh-/Rh-

Rh+ Rh- Rh- Rh+/Rh- Rh-/Rh- Rh+/Rh- Rh-/Rh- VI. Rh Factor – describe the presence or absence of another protein on blood cells. C. Cross parent heterozygous for the Rh factor with another parent who does not have the Rh factor. Rh+ Rh- Rh- Rh+/Rh- Rh-/Rh- Rh-/Rh- Rh+/Rh- Genotypic ratio 0 Rh+/Rh+ : 2 Rh+/Rh-: 2 Rh-/Rh- Phenotypic ratio 2 Rh positive: 2 Rh negative