Question

13) In genomic imprinting in mammals, a chromosome provided by the egg will express the H19 gene but not the IGF2 gene, as shown in the cartoon below Activator protein Insulator protein IGF2 OFF ON Maternal chromosome ICR H19 Enhancer The sperm-derived (paternal chromosome): Also expresses H19 but not IGF2 b. a. Uses another enhancer (not shown) to drive expression of IGF2 Undergoes chromatin modification to inactivate both the ICR region and the H19 c. gene d. Undergoes chromatin modification to inactivate the H19 gene but retains a functional ICR region 14) When Fi plants heterozygous at a single gene are crossed to one another, three genotypes will be found in the progeny at a 1:2:1 ratio. This type of genetic cross is known as a: a. Replicate cross b. Reciprocal cross c. test cross d. monohybrid cross 15) Assuming R and G genes are two, unlinked genes, and Mendel's law of independent assortment is correct, what phenotypic ratio would you expect to see if an individual with the genotype RrGg is self-crossed? a. 3:1 b. 9:3:3:1 d. 9:3:4

Answer 1

13. D
Igf2 only expressed if inherited from father - maternal copy is imprinted
H19 gene only expressed if inherited from mother - paternal copy is imprinted

14. Monohybrid cross

15. 9:3:3:1
Independent assortment it gives this ratio 9:3:3:1