$$\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$$

Question 1

Which of the following best describes the function of an operon in prokaryotic cells?

Accepted Answer

A cluster of genes under the control of a single promoter and operator, allowing coordinated regulation.

Question 2

A mutation in E. coli prevents the lac repressor from binding to the lac operator. What is the most likely outcome for the cell?

Accepted Answer

The lac operon will be continuously expressed, regardless of lactose presence.

Question 3

Which equation represents the flow of genetic information from genotype to phenotype?

Accepted Answer

$$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$

Question 4

How does DNA packing affect gene expression in eukaryotic cells?

Accepted Answer

It blocks gene expression by preventing transcription proteins from accessing DNA.

Question 5

Which of the following is an example of epigenetic inheritance?

Accepted Answer

Chemical modification of histone proteins that alters gene expression without changing the DNA sequence.

Question 6

Why do nerve cells and skin cells in your body have different structures and functions, despite having the same genes?

Accepted Answer

Selective gene expression causes different sets of genes to be active in each cell type.

Question 7

What must occur before RNA polymerase can bind to a promoter and transcribe a specific eukaryotic gene?

Accepted Answer

Transcription factors must bind to the DNA and promote RNA polymerase binding.

Question 8

Alternative RNA splicing allows a single gene to produce multiple polypeptides. Which of the following best explains this process?

Accepted Answer

Different combinations of exons are joined together to form different mRNAs.

Question 9

If the enzyme responsible for cleaving inactive insulin is deactivated, what effect will this have on insulin?

Accepted Answer

Insulin will remain inactive and unable to regulate blood sugar.

Question 10

Which of the following best describes the role of noncoding RNAs in gene expression?

Accepted Answer

They can bind to mRNA and either degrade it or block its translation.

Question 11

A gene has the sequence A A T T C G C G. What would be the sequence of an miRNA that turns off this gene?

Accepted Answer

U U A A G C G C

Question 12

Which of the following stages of gene expression can be regulated in both prokaryotic and eukaryotic cells?

Accepted Answer

Transcription, translation, mRNA degradation, protein activation, and protein degradation.

Question 13

Which equation best represents the relationship between the number of human genes and the number of polypeptides produced?

Accepted Answer

$$	ext{Number of polypeptides} \u003e 	ext{Number of genes}$$ due to alternative splicing

Question 14

Which of the following is NOT a mechanism by which gene expression is regulated in eukaryotes?

Accepted Answer

Direct translation of DNA into protein without mRNA

Question 15

Which of the following statements about the lac operon is correct?

Accepted Answer

The lac operon is induced when lactose inactivates the repressor.

Question 16

Which of the following is a consequence of X-chromosome inactivation in female mammals?

Accepted Answer

Only one X chromosome is active in each cell, leading to mosaic expression of traits.

Question 17

Which of the following best describes the role of transcription factors in eukaryotic gene regulation?

Accepted Answer

They bind to enhancers and promoters to facilitate RNA polymerase binding.

Question 18

Which of the following is a plausible effect of histone acetylation on gene expression?

Accepted Answer

It increases gene expression by loosening chromatin structure.

Question 19

Which of the following is a real-world example of gene regulation affecting phenotype?

Accepted Answer

Random X-chromosome inactivation in female cats leads to patchy fur coloration.

How Genes Are Controlled: Mechanisms of Gene Expression in Prokaryotes and Eukaryotes

Study Guide - Practice Questions