13. Mendelian Genetics

Which of the following statements best describes epistasis?

Epigenetic changes involving methylation can directly affect the phenotype of an individual or her offspring by ________.

a. Causing correlations between parents and children

b. Causing changes to the DNA that affect gene expression but not DNA sequence

c. Generating low heritability

d. Increasing the likelihood of monozygotic twinning

e. Sterilizing the DNA

Imagine repeating the experiment on epigenetic inheritance that is shown in Figure 19.6. You measure the amount of radioactive uridine (U) incorporated into Hnf4a mRNA in counts per minute (cpm) to determine the level of Hnf4a gene transcription in rats born to mothers fed either a normal diet or a low-protein diet. The results are 11,478 cpm for the normal diet and 7368 cpm for the low-protein diet. For this problem, your task is to prepare a graph similar to the one at the bottom of Figure 19.6 that shows the normalized results for the low-protein diet relative to the normal diet. Normalizing values means that the value obtained from one condition is expressed as 1.0 (the norm; the normal diet in this case) and the values obtained from any other conditions (low-protein diet in this case) are expressed as decimal values relative to the norm.