Question 1

Which of the following best explains how a fish can see equally well in both air and water?

Accepted Answer

The fish's eye cells regulate gene expression by using specific transcription factors for aerial and aquatic vision.

Question 2

Which cell type does NOT have exactly the same DNA as the others: embryo, liver, bone, muscle, or sperm?

Accepted Answer

Sperm

Question 3

Gene expression must be regulated in several dimensions. Which of the following is NOT a dimension mentioned in the study materials?

Accepted Answer

Temperature (body heat regulation)

Question 4

In bacteria, how does the trp operon respond when tryptophan levels are high?

Accepted Answer

Tryptophan acts as a corepressor, activating the trp repressor and shutting off transcription.

Question 5

Which statement correctly distinguishes between repressible and inducible operons?

Accepted Answer

A repressible operon is usually on and can be turned off by a repressor; an inducible operon is usually off and can be turned on by an inducer.

Question 6

Which of the following mechanisms allows eukaryotic cells to rapidly fine-tune gene expression in response to environmental changes?

Accepted Answer

Post-transcriptional regulation, such as alternative RNA splicing and mRNA degradation

Question 7

What is the effect of acetylation of histone tails on chromatin structure and gene expression?

Accepted Answer

Acetylation promotes a loose chromatin structure, making DNA accessible for transcription.

Question 8

Which of the following best describes epigenetic inheritance?

Accepted Answer

Inheritance of traits due to chemical modifications of DNA or histones that do not alter the DNA sequence.

Question 9

What is the role of control elements in the regulation of eukaryotic gene expression?

Accepted Answer

They are noncoding DNA segments that serve as binding sites for transcription factors.

Question 10

How does alternative RNA splicing contribute to protein diversity?

Accepted Answer

It allows a single gene to produce multiple mRNA variants by including or excluding different exons.

Question 11

Which region of eukaryotic mRNA influences its life span in the cytoplasm?

Accepted Answer

3' untranslated region (UTR)

Question 12

What is the effect of microRNAs (miRNAs) binding to target mRNAs?

Accepted Answer

If base pairing is perfect, mRNA is degraded; if imperfect, translation is blocked.

Question 13

Which of the following genetic changes can lead to cancer by affecting cell cycle control?

Accepted Answer

Epigenetic changes that increase expression of proto-oncogenes

Question 14

How can viruses contribute to the development of cancer in humans?

Accepted Answer

By integrating into the DNA of a cell and interfering with normal gene regulation

Question 15

Which of the following is a correct statement about co-expressed eukaryotic genes?

Accepted Answer

They can be scattered across different chromosomes but share the same combination of control elements.

Question 16

A mutation in the Ras gene leads to a hyperactive Ras protein. What is the likely consequence for the cell?

Accepted Answer

Increased cell division even in the absence of growth factor.

Question 17

Inherited mutations in the tumor-suppressor gene APC are commonly associated with which type of cancer?

Accepted Answer

Colorectal cancer

Question 18

Which formula best represents feedback inhibition in a metabolic pathway?

Accepted Answer

$$E_1$$ ightarrow $$E_2$$ ightarrow $$E_3$$ ightarrow 	ext{Product}$$, where the product inhibits E_1$

Question 19

Which process allows a cell to block the initiation of translation of selected mRNAs?

Accepted Answer

Binding of regulatory proteins to sequences or structures of the mRNA

Question 20

Which of the following is a multi-step process in the development of cancer?

Accepted Answer

Loss of tumor-suppressor gene APC, activation of Ras oncogene, loss of tumor-suppressor gene p53, and additional mutations

Regulating Gene Expression (Chapter 18): Mechanisms and Implications

Study Guide - Practice Questions