QCM : Gene Expression and RNA Processing — 10 questions

Question 1

1. What is the primary role of RNA polymerase during transcription in both prokaryotic and eukaryotic cells?

It recognizes promoter sequences and synthesizes RNA complementary to the DNA template strand.

It unwinds DNA and synthesizes DNA strands.

It processes pre-mRNA by splicing introns.

It transports mRNA from the nucleus to the cytoplasm.

Explication

RNA polymerase is responsible for recognizing specific promoter sequences and synthesizing RNA that is complementary to the DNA template strand. It unwinds the DNA and catalyzes the formation of phosphodiester bonds to produce the RNA transcript in the 5′-to-3′ direction.

Answer

It recognizes promoter sequences and synthesizes RNA complementary to the DNA template strand.

Question 2

2. What is the primary enzyme responsible for transcribing DNA into RNA?

DNA polymerase

RNA polymerase

Reverse transcriptase

Ligase

Explication

RNA polymerase synthesizes RNA from a DNA template during transcription, making it the key enzyme in this process. DNA polymerase, on the other hand, synthesizes DNA during replication, not transcription.

Answer

RNA polymerase

Question 3

3. Which of the following accurately describes the process of RNA splicing?

The addition of a 5′ cap and a poly-A tail.

The removal of introns and joining of exons, involving snRNPs and lariat formation.

The translation of mRNA into protein.

The removal of exons and joining of introns.

Explication

RNA splicing involves the removal of introns and the joining of exons to produce a continuous coding sequence. This process is mediated by small nuclear ribonucleoproteins (snRNPs) and involves the formation of a lariat structure at the branch point.

Answer

The removal of introns and joining of exons, involving snRNPs and lariat formation.

Question 4

4. Which of the following is a common feature of eukaryotic promoters?

TATA box

-35 and -10 regions

Pribnow box

operator sequence

Explication

The TATA box is a conserved promoter element in eukaryotes; bacteria typically have -10 and -35 regions instead.

Answer

It provides redundancy, reducing the impact of mutations at the third position of codons.

Answer

Processing splicing of pre-mRNA

Answer

Decodes mRNA codons and assembles amino acids into proteins

Answer

Encoding amino acids

Answer

Binding sites for RNA polymerase and sigma factor

Question 5

5. What is the significance of the genetic code being degenerate, especially at the third codon position?

It ensures that each amino acid is encoded by only one unique codon.

It prevents mutations from affecting protein synthesis.

It allows for multiple amino acids to be encoded by a single codon.

It provides redundancy, reducing the impact of mutations at the third position of codons.

Explication

The degeneracy of the genetic code, particularly at the third codon position, means that multiple codons can encode the same amino acid. This redundancy provides a buffer against mutations, as changes at the third position often do not alter the amino acid sequence of the resulting protein.

Question 6

6. What is the role of snRNPs in gene expression?

Initiating transcription

Processing splicing of pre-mRNA

Facilitating translation

Degrading mRNA

Explication

snRNPs are involved in splicing, removing introns from pre-mRNA to produce mature mRNA.

Question 7

7. What modification occurs at the 5' end of eukaryotic mRNA that enhances its stability?

Poly-A tail

5' cap

Splicing

Ubiquitination

Explication

The 5' cap is added to eukaryotic mRNA and protects it from degradation, aiding in stability and translation.

Question 8

8. Which statement correctly describes the function of the ribosome during translation?

Synthesizes DNA from RNA

Decodes mRNA codons and assembles amino acids into proteins

Transcribes DNA into mRNA

Removes introns from pre-mRNA

Explication

The ribosome decodes mRNA codons and assembles amino acids accordingly, synthesizing proteins.

Question 9

9. Which of the following is NOT a function associated with RNA modifications?

Enhancing mRNA stability

Facilitating splicing

Promoting ribozyme activity

Encoding amino acids

Explication

RNA modifications do not encode amino acids; rather, they modify RNA molecules to influence stability and function.

Question 10

10. In prokaryotic transcription, what are the roles of the -10 and -35 regions?

Binding sites for RNA polymerase and sigma factor

Start and stop codons

Termination signals

Enhances mRNA stability

Explication

The -10 and -35 regions are promoter sequences recognized by RNA polymerase and sigma factor, initiating transcription in bacteria.

QCM : Gene Expression and RNA Processing — 10 questions

Questions et réponses du QCM

1. What is the primary role of RNA polymerase during transcription in both prokaryotic and eukaryotic cells?

2. What is the primary enzyme responsible for transcribing DNA into RNA?

3. Which of the following accurately describes the process of RNA splicing?

4. Which of the following is a common feature of eukaryotic promoters?

5. What is the significance of the genetic code being degenerate, especially at the third codon position?

6. What is the role of snRNPs in gene expression?

7. What modification occurs at the 5' end of eukaryotic mRNA that enhances its stability?

8. Which statement correctly describes the function of the ribosome during translation?

9. Which of the following is NOT a function associated with RNA modifications?

10. In prokaryotic transcription, what are the roles of the -10 and -35 regions?

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