Molecular Biology Quiz: Transcription, Translation, and Gene Regulation

Flashcards covering key quiz concepts in molecular genetics, including transcription, translation, ribosomal function, mutations, and gene expression regulation.

Which statement about the genetic code is correct regarding redundancy?

The genetic code is redundant.

What cellular component catalyzes peptide bond formation during translation?

A ribosomal RNA (ribozyme) within the ribosome catalyzes peptide bond formation.

What is the structural composition of a ribosome?

A ribosome is a large rRNA and protein complex.

Why is the statement 'Ribosomes must bind to the 5′ cap before initiating translation' false for prokaryotic mRNA?

Prokaryotic mRNA molecules lack a 5′ cap, so ribosomes do not bind to a 5′ cap to initiate translation.

Why is using RNA as a template for protein synthesis advantageous for the cell over direct translation from DNA?

RNA allows for the formation of polyribosomes, increasing the efficiency of protein synthesis.

If a template strand of DNA has the base triplet 5' AGT 3', what is the corresponding mRNA codon transcribed?

3' UCA 5'

Is replicating different copies of DNA according to different physiological processes a method cells use to regulate protein levels?

No, cells do not replicate different copies of DNA according to different physiological processes to regulate the amount of a protein.

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in which step?

Specificity in the attachment of amino acids to tRNAs.

Why is the action of a protein that blocks TATA box binding protein function NOT a mechanism of post-transcriptional control?

Blocking the TATA box binding protein prevents the initiation of transcription, making it a transcriptional control mechanism rather than post-transcriptional.

How can 45 tRNAs recognize all 61 mRNA codons that specify amino acids?

The rules for base pairing between the third base of a codon and tRNA are flexible (wobble hypothesis).

What is the first event in translation initiation in eukaryotes?

The small subunit of the ribosome is assembled at the start codon AUG of mRNA with the initiator tRNA, Met-tRNA.

What are polyribosomes?

Groups of ribosomes reading a single mRNA simultaneously.

When does translation begin in prokaryotic cells?

As soon as transcription has begun (coupled transcription and translation).

Why is the statement 'miRNAs are produced from rRNAs' false?

miRNAs are not derived or produced from ribosomal RNAs (rRNAs).

Which type of mutation occurring immediately after the AUG start codon is likely to have the most serious effect on the polypeptide product?

A deletion of 2 nucleotides, which causes a frameshift mutation throughout the rest of the coding sequence.

Do nuclear pore complexes regulate the speed of protein export to control protein amounts in the cell?

No, nuclear pore complexes regulating the export speed of newly synthesized proteins from the nucleus into the cytoplasm is not a method used by cells to regulate protein levels.

Why do neurons and white blood cells perform vastly different functions despite sharing the same genome?

The neuron expresses some mRNAs that the white blood cell does not.

What is the main driver of distinct characteristics among different cell types in a multicellular organism?

The differential regulation of the transcription of genes transcribed by RNA polymerase II.

What is a true statement regarding the cellular function of RNAi?

RNAi destroys double-stranded viral RNA as a cellular defense system.