Q: Which equation best represents the negative regulation of the trp operon in E. coli when tryptophan is present?

$$\text{Inactive repressor} + \text{tryptophan} \rightarrow \text{Active repressor}$$

Q: Which equation best represents the effect of histone acetylation on chromatin structure?

$$\text{Acetylation} + \text{histone tails} \rightarrow \text{Loose chromatin structure}$$

Q: Alternative RNA splicing allows for the production of different mRNA molecules from the same primary transcript. Which equation best represents this process?

$$\text{Primary RNA transcript} \rightarrow \text{mRNA}_1 or$$ $$\text{mRNA}_2$$ \text{ (depending on exon/intron selection)}$

Q: During embryonic development, cytoplasmic determinants and inductive signals play a crucial role in cell differentiation. Which equation best represents the effect of cytoplasmic determinants?

$$\text{Zygote} \xrightarrow{\text{mitosis}} \text{Cells with different cytoplasmic determinants} \rightarrow \text{Differential gene expression}$$

Question 1

Which of the following best explains how two cells with identical genomes can perform different functions, as seen in the eye cells of Anableps anableps ('four-eyed fish')?

Accepted Answer

Differential gene expression, regulated by specific transcription factors, allows cells to express only the genes needed for their specialized function.

Question 2

In bacteria, which mechanism allows the cell to quickly shut down the production of enzymes when the end product of a metabolic pathway accumulates?

Accepted Answer

Feedback inhibition

Question 3

The operon model in bacteria involves a cluster of functionally related genes controlled by a single 'on-off switch.' Which component acts as the switch?

Accepted Answer

Operator

Question 4

Which equation best represents the negative regulation of the trp operon in E. coli when tryptophan is present?

Accepted Answer

$$	ext{Inactive repressor} + 	ext{tryptophan} ightarrow 	ext{Active repressor}$$

Question 5

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

Accepted Answer

The lac operon is usually off and is induced by allolactose, which inactivates the repressor.

Question 6

Which scenario best illustrates positive gene regulation in the lac operon?

Accepted Answer

Glucose is scarce, cAMP levels are high, CAP is active, and abundant lac mRNA is synthesized.

Question 7

Which chemical modification of histones is associated with activation of transcription in eukaryotic cells?

Accepted Answer

Histone acetylation

Question 8

Epigenetic inheritance refers to the transmission of traits by mechanisms not directly involving the nucleotide sequence. Which process is an example of epigenetic inheritance?

Accepted Answer

DNA methylation regulating expression of maternal or paternal alleles

Question 9

Which equation best represents the effect of histone acetylation on chromatin structure?

Accepted Answer

$$	ext{Acetylation} + 	ext{histone tails} ightarrow 	ext{Loose chromatin structure}$$

Question 10

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

Accepted Answer

Enhancers are distal control elements that bind activators and increase transcription of specific genes.

Question 11

Alternative RNA splicing allows for the production of different mRNA molecules from the same primary transcript. Which equation best represents this process?

Accepted Answer

$$	ext{Primary RNA transcript} ightarrow 	ext{mRNA}_1 or$$ $$	ext{mRNA}_2$$ 	ext{ (depending on exon/intron selection)}$

Question 12

Which of the following mechanisms can block the initiation of translation in eukaryotic cells?

Accepted Answer

Regulatory proteins binding to the 3' UTR of mRNA

Question 13

MicroRNAs (miRNAs) regulate gene expression by binding to mRNA. What is the outcome if the miRNA is completely complementary to its target mRNA?

Accepted Answer

The mRNA is degraded.

Question 14

During embryonic development, cytoplasmic determinants and inductive signals play a crucial role in cell differentiation. Which equation best represents the effect of cytoplasmic determinants?

Accepted Answer

$$	ext{Zygote} \xrightarrow{	ext{mitosis}} 	ext{Cells with different cytoplasmic determinants} ightarrow 	ext{Differential gene expression}$$

Question 15

Which gene is known as a 'master regulatory gene' for muscle cell differentiation, and what is its primary function?

Accepted Answer

MyoD; encodes a transcription factor that commits cells to becoming skeletal muscle.

Question 16

Which equation best represents the conversion of a proto-oncogene to an oncogene by gene amplification?

Accepted Answer

$$	ext{Proto-oncogene} \xrightarrow{	ext{amplification}} 	ext{multiple copies} ightarrow 	ext{Oncogene}$$

Question 17

Mutations in which gene are commonly associated with inherited breast cancer, and how can these mutations be detected?

Accepted Answer

BRCA1 or BRCA2; detected by DNA sequencing.

Question 18

Which of the following best describes the multistep model of cancer development?

Accepted Answer

Multiple mutations in oncogenes and tumor-suppressor genes are required for full-fledged cancer.

Regulation of Gene Expression (Chapter 18): Mechanisms and Implications

Study Guide - Practice Questions

Study Guide - Flashcards