Q: Which of the following equations correctly represents the central dogma of molecular biology as described in the study materials?

$$DNA \rightarrow pre\text{-}mRNA \rightarrow \text{mature mRNA} \rightarrow \text{Protein}$$

Question 1

Which of the following is NOT a function of the 5' cap added to eukaryotic mRNA during posttranscriptional modification?

Accepted Answer

It increases the rate of mRNA splicing.

Question 2

A mutation in the spliceosome complex would most likely result in which of the following cellular outcomes?

Accepted Answer

Retention of introns in mature mRNA.

Question 3

Alternative splicing allows a single gene to produce multiple protein isoforms. Which process directly enables this diversity?

Accepted Answer

Selective joining of different exons during mRNA processing.

Question 4

Which enzyme is responsible for adding the poly-A tail to the 3' end of eukaryotic mRNA?

Accepted Answer

Poly(A) polymerase

Question 5

A patient is diagnosed with β-thalassemia, a disease caused by defective mRNA splicing. Which molecular event is most likely disrupted?

Accepted Answer

Removal of introns from pre-mRNA

Question 6

Which of the following best describes the process of RNA editing in eukaryotes?

Accepted Answer

Alteration of nucleotide sequence post-transcription, such as C to U or A to I conversions

Question 7

Which of the following small non-coding RNAs is involved in gene silencing by forming the RNA-induced silencing complex (RISC)?

Accepted Answer

siRNA

Question 8

During mRNA processing, which sequence signals the site for polyadenylation?

Accepted Answer

A polyadenylation signal sequence in the pre-mRNA

Question 9

Which of the following equations correctly represents the central dogma of molecular biology as described in the study materials?

Accepted Answer

$$DNA ightarrow pre	ext{-}mRNA ightarrow 	ext{mature mRNA} ightarrow 	ext{Protein}$$

Question 10

A researcher discovers a new long non-coding RNA (lncRNA) that acts as a 'sponge' for microRNAs. What is the most likely effect of this lncRNA on gene expression?

Accepted Answer

It prevents microRNAs from binding to their target mRNAs, thus increasing target gene expression.

Question 11

Which of the following statements about microRNAs (miRNAs) is TRUE?

Accepted Answer

miRNAs can induce mRNA degradation if they bind perfectly to their target.

Question 12

Which of the following is a direct consequence of defective mRNA export from the nucleus?

Accepted Answer

Reduced protein synthesis due to lack of mRNA in the cytoplasm

Question 13

Which molecular event is most likely to increase the stability of an mRNA molecule in eukaryotes?

Accepted Answer

Addition of a poly-A tail at the 3' end

Question 14

A scientist is studying the effects of siRNA on viral gene expression. Which pathway is most likely involved in the silencing of viral mRNA?

Accepted Answer

siRNA is processed from double-stranded RNA and incorporated into RISC, which degrades viral mRNA.

Question 15

Which of the following best explains why alternative splicing is important in multicellular organisms?

Accepted Answer

It increases protein diversity from a single gene.

Question 16

Which of the following is a real-world example of RNA editing that changes the coding potential of a gene product?

Accepted Answer

Editing of ApoB mRNA in humans to produce ApoB-48 and ApoB-100

Question 17

Which of the following steps occurs FIRST during the processing of eukaryotic pre-mRNA?

Accepted Answer

Addition of the 5' cap

Question 18

Which of the following statements about the spliceosome is correct?

Accepted Answer

It is composed of snRNA and proteins.

Question 19

Which of the following equations represents the number of adenine nucleotides typically added during polyadenylation?

Accepted Answer

$$\sim 200$$

Question 20

A mutation prevents the binding of cap-binding complex proteins to mRNA. What is the most likely consequence?

Accepted Answer

Impaired export of mRNA from the nucleus

Post-Transcriptional Regulation in Eukaryotes: Mechanisms and Processes

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