Q: Which of the following equations best represents the chemical modification of cytosine to 5-methylcytosine?

$$\mathrm{Cytosine} + \mathrm{CH}_3 \rightarrow \mathrm{5\text{-}methylcytosine}$$

Question 1

Which of the following best describes epigenetics?

Accepted Answer

The study of heritable changes in gene expression that do not involve changes to the DNA sequence.

Question 2

DNA methylation most commonly involves the addition of a methyl group to which nucleotide base, and what is the resulting modified base called?

Accepted Answer

Cytosine; 5-methylcytosine

Question 3

Which of the following is a direct consequence of DNA methylation at CpG dinucleotides?

Accepted Answer

Suppression of gene expression by altering chromatin structure

Question 4

In honeybees, what is the role of royal jelly in determining whether a larva becomes a queen or a worker?

Accepted Answer

It suppresses Dnmt3, reducing DNA methylation and allowing expression of queen-specific genes.

Question 5

Which of the following is NOT a type of histone modification that can affect chromatin structure and gene expression?

Accepted Answer

Addition of ribose groups

Question 6

X inactivation in female mammals is an example of which epigenetic process?

Accepted Answer

Dosage compensation

Question 7

The Xist gene is crucial for X inactivation because it:

Accepted Answer

Produces a long noncoding RNA that coats the inactive X chromosome and suppresses transcription.

Question 8

A female mouse heterozygous for X-linked coat color alleles (one for black, one for white) displays patches of both colors. This phenomenon is best explained by:

Accepted Answer

Random X inactivation in different cells during development

Question 9

Which syndrome results from a deletion on chromosome 15 inherited from the mother, and what is the key gene involved?

Accepted Answer

Angelman syndrome; UBE3A

Question 10

Genomic imprinting can lead to different phenotypes depending on the parent of origin. Which hypothesis explains the evolutionary reason for imprinting?

Accepted Answer

Genetic conflict hypothesis

Question 11

Which of the following best explains why monozygotic twins can have different phenotypes despite having identical DNA sequences?

Accepted Answer

Epigenetic modifications acquired after fertilization

Question 12

Behavioral epigenetics has shown that early life experiences can have long-lasting effects on gene expression. In rats, increased maternal licking and grooming leads to:

Accepted Answer

Decreased methylation of stress-response genes, making offspring less fearful

Question 13

Which of the following equations best represents the chemical modification of cytosine to 5-methylcytosine?

Accepted Answer

$$\mathrm{Cytosine} + \mathrm{CH}_3 ightarrow \mathrm{5	ext{-}methylcytosine}$$

Question 14

Which of the following statements about the epigenome is correct?

Accepted Answer

The epigenome refers to the overall pattern of chromatin modifications in an individual organism.

Question 15

A patient with Klinefelter syndrome (XXY) would be expected to have how many Barr bodies in each somatic cell?

Accepted Answer

1

Question 16

Which of the following best describes the mechanism by which Xist RNA leads to X chromosome inactivation?

Accepted Answer

Xist RNA coats the inactive X chromosome, recruiting proteins that modify histones and silence gene expression.

Question 17

Which of the following is a real-world example of epigenetic changes affecting phenotype without altering the DNA sequence?

Accepted Answer

Differences in flower shape in Linaria vulgaris due to epigenetic variation

Epigenetics: Mechanisms and Biological Implications

Study Guide - Practice Questions

Study Guide - Flashcards