Transcription and Translation

What is the function of mRNA in gene expression?

• Catalyzes peptide bond formation

• Carries genetic information from DNA to the ribosome

• Transports amino acids to the ribosome

• Forms the core structure of ribosomes

Answer explanation

mRNA carries genetic information from DNA to the ribosome, where it serves as a template for protein synthesis. This is crucial for gene expression, making it the correct choice among the options.

Which RNA molecule has an anticodon and binds specific amino acids?

• mRNA

• rRNA

• tRNA

• snRNA

Answer explanation

tRNA (transfer RNA) has an anticodon that pairs with the codon on mRNA and carries specific amino acids to the ribosome during protein synthesis, making it essential for translating genetic information into proteins.

What determines RNA function?

• The DNA sequence of introns

• The sequence of RNA bases and the structure of the RNA molecule

• The presence of a start codon

• The ribosome size

Answer explanation

RNA function is primarily determined by the sequence of RNA bases and its structure, which influence how it interacts with other molecules and performs its roles in the cell.

What is the role of rRNA?

• It carries genetic information to the ribosome.

• It is a functional building block of ribosomes.

• It acts as an enzyme for splicing introns.

• It transports amino acids to the ribosome.

Answer explanation

rRNA, or ribosomal RNA, is a key component of ribosomes, which are the cellular machinery for protein synthesis. It provides structural support and catalyzes the formation of peptide bonds, making it essential for ribosome function.

Transcription involves:

• Synthesizing a protein from RNA.

• Copying a sequence of DNA into RNA.

• Adding amino acids to a growing peptide chain.

• Splicing exons together.

Answer explanation

Transcription is the process of copying a sequence of DNA into RNA, making the correct answer 'Copying a sequence of DNA into RNA.' The other options describe different processes in protein synthesis and RNA processing.

Which DNA strand serves as the template during transcription?

• Coding strand

• Sense strand

• Noncoding strand

• Complementary strand

Answer explanation

The noncoding strand, also known as the template strand, is used during transcription to synthesize RNA. It provides the complementary sequence to the RNA being formed, while the coding and sense strands are not directly involved.

RNA polymerase synthesizes RNA in which direction?

• 3’ to 5’

• 5’ to 3’

• Bidirectionally

• It depends on the gene being transcribed.

Answer explanation

RNA polymerase synthesizes RNA in the 5’ to 3’ direction, meaning it adds nucleotides to the 3’ end of the growing RNA strand. This is a fundamental aspect of RNA synthesis.

What modification involves adding a poly-A tail to an mRNA transcript?

• Alternative splicing

• Post-transcriptional modification

• Transcription initiation

• Codon recognition

Answer explanation

The addition of a poly-A tail to an mRNA transcript is a key aspect of post-transcriptional modification, which occurs after transcription and enhances mRNA stability and translation efficiency.

What is the significance of alternative splicing?

• It enhances mRNA stability.

• It generates different versions of mRNA from the same transcript.

• It prevents errors in DNA replication.

• It increases RNA polymerase activity.

Answer explanation

Alternative splicing is significant because it generates different versions of mRNA from the same transcript, allowing for diverse protein products and increasing the functional complexity of the genome.

In prokaryotes, translation begins:

• Only after transcription is complete.

• While transcription is still occurring.

• In the nucleus.

• After intron splicing.

Answer explanation

In prokaryotes, translation can begin while transcription is still occurring because both processes happen in the cytoplasm simultaneously, allowing ribosomes to start protein synthesis before the mRNA is fully transcribed.