Question 1 Question 2 Assume independent assortment and star

Question 1

Question 2

Assume independent assortment and start with a typical heterozygous F₁ plant (A/a ; B/b):

What genotypic ratio is produced from testcrossing the plant?

9 (A/a ; B/b); 3 (A/–; b/b); 3 (a/a ; B/–); 1 (a/a ; b/b)

9 (A/–; B/–); 3 (A/–; b/b); 3 (a/a ; B/–); 1 (a/a ; b/b)

1 (A/–; B/–); 1 (A/–; b/b); 1 (a/a ; B/–); 1 (a/a ; b/b)

1 (A/a ; B/b); 1 (A/A ; b/b); 1 (a/a ; B/B); 1 (a/a ; b/b)

1 (A/a ; B/b); 1 (A/a ; b/b); 1 (a/a ; B/b); 1 (a/a ; b/b)

Question 3

When a cell of genotype A/a ; B/b ; C/c having all the genes on separate chromosome pairs divides mitotically, what are the genotypes of the daughter cells?

A; a; B; b; C; c

A/a; A/A; a/a; B/b; B/B; b/b; C/c; C/C; c/c

A/a; A/A; a/a

A/a; B/b; C/c

A; B; C

From the pedigree in Figure 3-25, what principle can you deduce about the inheritance of mitochondrial disease from affected fathers?
	Affected fathers rarely transmit mitochondrial disease genes to their progeny. Affected fathers do not transmit mitochondrial disease genes to their progeny. Affected fathers should be able to pass mitochondrial disease genes to their sons, but it is rare. Affected fathers have a nuclear factor that inactivates the ability to transmit the mitochondrial disease genes to their progeny.

Figure 3-25 Introduction to Genetic Analysis, Eleventh Edition 2015 W. H. Freeman and Company

Solution

ANSWER FOR QUESTION 1:

Human mitochondrial DNA is only inherited from the mothers. So, the correct option would be,
(b) Affected fathers do not transmit mitochondrial disease genes to their progeny.

ANSWER FOR QUESTION 2:

The expected phenotypic and genotypic ratios from the testcross of A/a ; B/b is
1 A/a ; B/b
1 A/a ; b/b
1 a/a ; B/b
1 a/a ; b/b
So, that would be option (e).

ANSWER FOR QUESTION 3:

Mitosis produces cells with the same starting genotype: A/a ; B/b ; C/c.
Hence answer would be option (d) A/a ; B/b ; C/c