Q: Which equation correctly represents the direction of RNA synthesis during transcription?

$$\text{RNA synthesis:}~5' \rightarrow 3'$$

Question 1

Which of the following best describes the role of enhancer elements in eukaryotic transcription, as illustrated in the first image?

Accepted Answer

Enhancers are DNA sequences that increase transcription by recruiting activator proteins, which interact with the promoter via DNA looping.

Question 2

In the context of eukaryotic mRNA processing, which modification is represented by the 'Cap' structure in the second image, and what is its primary function?

Accepted Answer

The 'Cap' is a methylated guanosine added to the 5' end, which protects mRNA from nucleases and aids in ribosome binding.

Question 3

Based on the third image, what effect does acetylation of histone proteins have on chromatin structure and gene expression?

Accepted Answer

Acetylation neutralizes the positive charge of histones, loosening DNA binding and promoting transcription.

Question 4

Which equation correctly represents the direction of RNA synthesis during transcription?

Accepted Answer

$$	ext{RNA synthesis:}~5' ightarrow 3'$$

Question 5

Which enzyme is responsible for catalyzing the addition of the poly(A) tail to eukaryotic mRNA, and what is the signal sequence for this modification?

Accepted Answer

Poly(A) polymerase; signal sequence is $$AAUAAA$$

Question 6

Which of the following statements about the coupling of transcription and translation in prokaryotes is correct?

Accepted Answer

Translation of mRNA can begin before transcription is complete due to the lack of a nuclear envelope.

Question 7

Which of the following is NOT a function of the poly(A) tail in eukaryotic mRNA?

Accepted Answer

Initiates transcription by recruiting RNA polymerase

Question 8

Which equation best describes the relationship between mRNA half-life ($$t_{1/2}) $$and degradation rate ($$k) in $$eukaryotic cells?

Accepted Answer

$$t_{1/2} = \frac{\ln 2}{k}$$

Question 9

Which of the following statements about RNA polymerase II (RNAPII) is correct?

Accepted Answer

RNAPII synthesizes mRNA and is highly sensitive to $$\alpha-$$amanitin.

Question 10

Which of the following best explains why errors in RNA transcription are less critical than errors in DNA replication?

Accepted Answer

RNA molecules are temporary and can be replaced, while DNA errors are permanent and heritable.

Question 11

Which of the following sequences is most likely to be found at the 5' splice site of an intron in eukaryotic pre-mRNA?

Accepted Answer

$$GU$$

Question 12

Which of the following is a key function of the C-terminal domain (CTD) of RNA polymerase II?

Accepted Answer

Coordinates mRNA processing events such as capping, splicing, and polyadenylation.

Question 13

Which of the following best describes the process of alternative splicing?

Accepted Answer

A single gene can produce multiple mRNA variants by selectively including or excluding certain exons.

Question 14

Which of the following statements about histone acetylation is correct?

Accepted Answer

Histone acetylation is catalyzed by HATs and promotes transcription by loosening chromatin structure.

Question 15

Which of the following is NOT a modification required for eukaryotic mRNA to be exported from the nucleus?

Accepted Answer

Addition of a promoter sequence

Question 16

Which of the following best describes the function of the exon junction complex (EJC) in mRNA processing?

Accepted Answer

EJC is deposited at exon-exon junctions and is required for efficient export and regulation of mRNA.

Question 17

Which of the following is a plausible consequence of a mutation in the TATA box of a eukaryotic gene promoter?

Accepted Answer

Reduced binding of transcription factors, leading to decreased transcription initiation.

Question 18

Which of the following best describes the role of the sigma factor in bacterial transcription?

Accepted Answer

Sigma factor directs RNA polymerase to specific promoter sequences, ensuring proper initiation of transcription.

Question 19

Which of the following is a real-world example of the importance of alternative splicing in human biology?

Accepted Answer

The human Titin gene produces multiple protein isoforms involved in muscle formation through alternative splicing.

Gene Expression I: Transcription – Mechanisms and Regulation

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