Question 1

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

Accepted Answer

A group of genes that are transcribed together and regulated by a single promoter and operator.

Question 2

In the trp operon, what happens when tryptophan levels are high in the bacterial cell?

Accepted Answer

Tryptophan binds to the repressor, activating it, and the repressor binds to the operator to block transcription.

Question 3

Which of the following is true about the lac operon in E. coli?

Accepted Answer

Allolactose binds to the repressor, inactivating it and allowing transcription of the lac genes.

Question 4

Which of the following best explains the difference between repressible and inducible operons?

Accepted Answer

Repressible operons are usually on and can be turned off, while inducible operons are usually off and can be turned on.

Question 5

Which of the following modifications would most likely increase gene expression in eukaryotic cells?

Accepted Answer

Histone acetylation, which loosens chromatin structure and makes DNA more accessible.

Question 6

A mutation causes a eukaryotic cell to have hyperactive DNA methyltransferase enzymes. What is the most likely effect on gene expression?

Accepted Answer

Gene expression will decrease due to increased chromatin condensation.

Question 7

Which of the following statements about epigenetic inheritance is correct?

Accepted Answer

Epigenetic modifications can be heritable but do not change the DNA sequence.

Question 8

During eukaryotic gene expression, what is the role of transcription factors?

Accepted Answer

They bind to control elements in DNA to increase or decrease transcription.

Question 9

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

Accepted Answer

Alternative splicing of pre-mRNA.

Question 10

A scientist observes that two genetically identical mice have different fur colors. Which mechanism best explains this phenomenon?

Accepted Answer

Epigenetic modifications such as DNA methylation and histone acetylation.

Question 11

Which of the following best describes the function of microRNAs in eukaryotic gene regulation?

Accepted Answer

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

Question 12

In a scenario where a eukaryotic cell fails to undergo apoptosis during development, what is a likely outcome?

Accepted Answer

Abnormal tissue structures, such as webbed fingers or toes.

Question 13

Which of the following is a direct result of histone acetylation?

Accepted Answer

Increased accessibility of DNA for transcription.

Question 14

A mutation in the operator region of the lac operon prevents the repressor from binding. What is the most likely consequence?

Accepted Answer

The lac genes will be transcribed continuously, even in the absence of lactose.

Question 15

Which of the following equations best represents the relationship between DNA, mRNA, and protein in gene expression?

Accepted Answer

$$DNA \xrightarrow{transcription} mRNA \xrightarrow{translation} Protein$$

Question 16

Which of the following is NOT a stage at which eukaryotic gene expression can be regulated?

Accepted Answer

Replication of DNA.

Question 17

A patient is found to have a genetic disorder caused by improper pattern formation during embryonic development. Which gene type is most likely mutated?

Accepted Answer

Homeotic genes.

Question 18

Which of the following best describes the role of cytoplasmic determinants in early embryonic development?

Accepted Answer

They are substances in the egg that influence gene expression and cell fate.

Question 19

Which of the following scenarios best illustrates induction during embryonic development?

Accepted Answer

A group of cells releases signaling molecules that cause neighboring cells to change gene expression.

Regulation of Gene Expression and Cell Specialization: Prokaryotic and Eukaryotic Mechanisms

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