Question 1

Which of the following best describes the effect of histone acetylation on gene expression, as illustrated in the provided image?

Accepted Answer

Histone acetylation loosens chromatin structure, making DNA more accessible for transcription.

Question 2

In the context of the lac operon, what is the role of allolactose?

Accepted Answer

Allolactose acts as an inducer, inactivating the repressor and allowing transcription.

Question 3

Which of the following statements about DNA methylation is correct?

Accepted Answer

DNA methylation is associated with long-term inactivation of genes during cellular differentiation.

Question 4

A mutation in the trp operon causes the repressor protein to be unable to bind tryptophan. What is the most likely outcome?

Accepted Answer

The operon will be permanently active, leading to continuous tryptophan synthesis.

Question 5

Which of the following best explains why identical twins can have different susceptibilities to genetically based diseases, as suggested by the image of the two mice?

Accepted Answer

Epigenetic modifications, such as DNA methylation, can lead to differences in gene expression.

Question 6

Which of the following is a function of tumor-suppressor proteins?

Accepted Answer

Repairing damaged DNA and inhibiting the cell cycle.

Question 7

What is the primary difference between general and specific transcription factors in eukaryotic gene regulation?

Accepted Answer

General transcription factors are required for all protein-coding genes, while specific transcription factors regulate particular genes.

Question 8

Which process allows a single gene to code for multiple proteins in eukaryotes?

Accepted Answer

Alternative RNA splicing

Question 9

In the multistep model of cancer development, which genetic event is typically the first step in the progression to colorectal cancer, as shown in the provided image?

Accepted Answer

Loss of a tumor-suppressor gene such as APC

Question 10

Which of the following best describes the role of microRNAs (miRNAs) in gene regulation?

Accepted Answer

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

Question 11

What is the effect of a mutation that inactivates the p53 gene in a cell?

Accepted Answer

The cell will be unable to initiate apoptosis in response to DNA damage.

Question 12

Which of the following mechanisms is responsible for the simultaneous expression of multiple, scattered genes in eukaryotes?

Accepted Answer

The presence of identical control elements in the regulatory regions of each gene

Question 13

Which of the following is a likely consequence of a mutation that prevents the addition of ubiquitin to proteins?

Accepted Answer

Proteins will accumulate in the cell due to decreased degradation.

Question 14

Which of the following best describes the process of induction during embryonic development, as shown in the provided image?

Accepted Answer

Signal molecules from one cell influence gene expression in nearby cells.

Question 15

Which of the following is true about the CRISPR-Cas9 system in bacteria?

Accepted Answer

It is a defense system that uses small noncoding RNAs to target viral DNA.

Question 16

Which of the following is a direct result of the binding of an activator protein to an enhancer in eukaryotic gene regulation?

Accepted Answer

Increased assembly of the transcription initiation complex at the promoter

Question 17

Which of the following best explains why eukaryotic mRNA is generally more stable than prokaryotic mRNA?

Accepted Answer

Eukaryotic mRNA contains a 5' cap and poly-A tail that protect it from degradation.

Question 18

Which of the following is a characteristic of repressible operons such as the trp operon?

Accepted Answer

They are usually on and can be turned off by a repressor bound to the operator.

Question 19

Which of the following best describes epigenetic inheritance?

Accepted Answer

Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence.

Regulation of Gene Expression in Prokaryotes and Eukaryotes

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