Question 1

Which of the following best describes the function of an operon in bacterial gene regulation?

Accepted Answer

A group of functionally related genes controlled by a single 'on-off switch' and includes the operator, promoter, and the genes they control.

Question 2

What is the role of the trp repressor in the trp operon?

Accepted Answer

It binds to the operator only in the presence of its corepressor tryptophan, turning the operon off.

Question 3

Which molecule acts as an inducer in the lac operon system?

Accepted Answer

Allolactose

Question 4

How does CAP (catabolite activator protein) regulate the lac operon when glucose is scarce?

Accepted Answer

CAP is activated by binding with cyclic AMP (cAMP) and attaches to the promoter, increasing transcription.

Question 5

Which chemical modification to histone proteins is associated with increased transcription?

Accepted Answer

Histone acetylation

Question 6

What is the effect of DNA methylation on gene expression?

Accepted Answer

It decreases transcription by condensing chromatin and reducing access to DNA.

Question 7

Which of the following is TRUE about enhancers in eukaryotic gene expression?

Accepted Answer

Enhancers can be located far away from the gene they regulate and increase transcription when activator proteins bind to them.

Question 8

Which process allows a single gene to produce multiple different proteins in eukaryotes?

Accepted Answer

Alternative RNA splicing

Question 9

What is the primary difference between heterochromatin and euchromatin?

Accepted Answer

Heterochromatin is more condensed and usually not expressed, while euchromatin is less condensed and more transcriptionally active.

Question 10

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

Accepted Answer

Repair damaged DNA and inhibit the cell cycle

Question 11

A mutation in the ras gene can lead to which of the following outcomes?

Accepted Answer

Production of a hyperactive Ras protein and increased cell division

Question 12

Which equation best represents the relationship between enzyme activity and feedback inhibition in the tryptophan synthesis pathway?

Accepted Answer

$$v = \frac{V_{max}[S]}{K_m + [S] + [I]}$$

Question 13

Which of the following scenarios would most likely result in the conversion of a proto-oncogene to an oncogene?

Accepted Answer

Amplification, increasing the number of copies of a proto-oncogene.

Question 14

Which statement best explains why multiple somatic mutations are generally needed for a cell to become fully cancerous?

Accepted Answer

Cancer development usually requires activation of at least one oncogene and mutation or loss of several tumor-suppressor genes.

Question 15

Which of the following is an example of post-transcriptional regulation?

Accepted Answer

Alternative RNA splicing to produce different mRNAs from the same gene.

Question 16

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

Accepted Answer

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

Question 17

Which of the following best describes epigenetic inheritance?

Accepted Answer

Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence, such as DNA methylation or histone modification.

Question 18

Which of the following would most likely decrease the transcription of a gene in eukaryotic cells?

Accepted Answer

Methylation of cytosine bases in the gene's promoter region

Question 19

Which process is illustrated by the following equation, where $$[CAP] is $$the concentration of catabolite activator protein and $$[cAMP] is $$the concentration of cyclic AMP?

$$[CAP^*] = [CAP] 	imes [cAMP]$$

Accepted Answer

Activation of CAP by cAMP in the lac operon

Question 20

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

Accepted Answer

Mutations in the p53 tumor-suppressor gene can prevent suppression of the cell cycle, leading to cancer.

Regulation of Gene Expression and Cancer Development

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