Chapter 3: Transmission Genetics

Segregation of 2 or more genes P1: round yellow (RRYY) x wrinkled green (rryy) What is the ratio of Round yellow : round green : wrinkled yellow : wrinkled green

- Round : wrinkled = 3:1 - Yellow : green = 3:1 - Pr(round)=3/4, Pr (wrinkled)=1/4, Pr(yellow)=3/4, Pr(green)=1/4 - Round yellow : round green : wrinkled yellow : wrinkled green = ¾ x ¾ : ¾ x ¼ : ¼ x ¾ : ¼ x ¼ = 9/16 : 3/16 : 3/16 : 1/16 = 9 : 3 : 3 : 1

Testcross

A cross between an organism that has dominant phenotype, but unknown genotype, and an organism that is homozygous for the recessive allele

The common grackle is a species of robin-sized blackbirds that are fairly common (hence the name) over most of the United States. Suppose that long tails (L) are dominant to short tails in these birds. A female short-tailed grackle mates with a male long-tailed grackle who had one parent with a long tail and one parent with a short tail. A. What is the male's genotype? B. How many of each genotype will be found in the F1 generation (assume 4 offspring)? C. How many of each phenotype will be found in the F1 generation (assume 4 offspring)?

A. Ll B. LL: 0 Ll: 2 ll: 2 C. Long tail: 2 Short tail: 2

WwGgYyIi x WwGgYyIi (W : round, w : wrinkled, G : yellow, g : green, Y : purple, y: white, I: inflated pod, i: constricted pod) A.) What is the probability of WwGGYYii genotype in the offspring? B.) What is the probability that offspring phenotype is round, green, white, and inflated ?

A.) 1/128 B.) 9/256 -Genotype: (1 WW + 2 Ww + 1 ww) x (1 GG+ 2 Gg + 1 gg) x (1 YY + 2 Yy + 1 yy) x (1 II + 2 Ii + 1 ii) -Pr(WW)= 1/4 -Pr(Ww)= 2/4 -Pr(ww)= 1/4 -Phenotype = (3 round + 1 wrinkled) x (3yellow + 1 green) x (3 purple + 1 white) x ( 3 inflated + 1 constricted) -Pr(Round)= 3/4 -Pr(Wrinkled)= 1/4

Three or more gene WwGgYy x WwGgYy (W : round, w : wrinkled, G : yellow, g : green, Y : purple, y: white) A.) What is the probability of WwGgYy genotype in the offspring? B.) What is the probability of WwGGYy genotype in the offspring? C.) What is the probability that offspring phenotype is round, yellow, and purple ? D.) What is the probability that offspring phenotype is round, yellow, and white ?

A.) 1/8 B.) 1/16 C.) 27/64 D.) 9/64 - WwGgYy x WwGgYy = (Ww x Ww) x (Gg x Gg) x(Yy x Yy) - Genotype = (1 WW + 2 Ww + 1 ww) x (1 GG+ 2 Gg + 1 gg) x (1 YY + 2 Yy + 1 yy) -Pr(WW)=1/4 Pr(Ww)=2/4 Pr(ww)=1/4 -Phenotype = (3 round + 1 wrinkled) x (3yellow + 1 green) x (3 purple + 1 white) -Pr(round)=3/4 -Pr(wrinkled)=1/4

The ability to curl your tongue up on the sides (T, tongue rolling) is dominant to not being able to roll your tongue (t). A woman who can roll her tongue marries a man who cannot. Their first child has his father's phenotype. What are the genotypes of the mother, father, and child?

C. Mother (Tt), Father (tt), child (tt)