Question 1

Which of the following best describes the role of mRNA in gene expression, as illustrated in the 'Paramecium Parlor' comic?

Accepted Answer

mRNA serves as a messenger, carrying genetic instructions from DNA in the nucleus to the ribosome in the cytoplasm.

Question 2

The images of a pig expressing a jellyfish gene and a tobacco plant expressing a firefly gene demonstrate which property of the genetic code?

Accepted Answer

The genetic code is nearly universal, allowing genes from one species to be expressed in another.

Question 3

In the meme where RNA is copying from DNA, which process is being humorously depicted?

Accepted Answer

Transcription

Question 4

Refer to the diagram showing RNA polymerase moving along DNA. Which direction does RNA polymerase synthesize the RNA strand?

Accepted Answer

RNA polymerase synthesizes RNA in the 5' → 3' direction.

Question 5

Which of the following is a function of the 5' cap and poly-A tail added to eukaryotic mRNA?

Accepted Answer

They facilitate the export of mRNA from the nucleus, protect mRNA from degradation, and help ribosomes attach to the mRNA.

Question 6

During translation, what is the function of tRNA as shown in the structural diagrams?

Accepted Answer

tRNA carries a specific amino acid and matches its anticodon to the mRNA codon during protein synthesis.

Question 7

What enzyme is responsible for attaching the correct amino acid to its corresponding tRNA, as shown in the aminoacyl-tRNA synthetase diagram?

Accepted Answer

Aminoacyl-tRNA synthetase

Question 8

If the DNA coding sequence is TCT, what is the anticodon sequence on the tRNA that binds the mRNA codon?

Accepted Answer

AGA

Question 9

Which ribosomal site holds the tRNA carrying the growing polypeptide chain during translation?

Accepted Answer

P site (Peptidyl-tRNA binding site)

Question 10

What is the correct sequence of events during the elongation phase of translation?

Accepted Answer

Codon recognition, peptide bond formation, translocation

Question 11

A mutation changes a codon from UAU (tyrosine) to UAA (stop). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 12

Which of the following best explains why insertions and deletions often have more severe effects than substitutions?

Accepted Answer

Insertions and deletions can cause frameshift mutations, altering the reading frame and potentially changing every amino acid downstream.

Question 13

Which of the following mutagens is a physical agent that can cause mutations in DNA?

Accepted Answer

UV radiation

Question 14

A frameshift mutation occurs when:

Accepted Answer

One or more nucleotide pairs are inserted or deleted, altering the reading frame.

Question 15

Which of the following is NOT a function of ribosomes in translation?

Accepted Answer

Editing DNA sequences before transcription

Question 16

Which of the following best describes the 'wobble' phenomenon in tRNA?

Accepted Answer

Flexible pairing at the third base of a codon allows some tRNAs to bind to more than one codon.

Question 17

During the termination phase of translation, what happens when a stop codon is reached?

Accepted Answer

A release factor binds to the A site, causing the addition of a water molecule and releasing the polypeptide.

Question 18

Which of the following best explains why some antibiotics can target bacterial ribosomes without harming eukaryotic cells?

Accepted Answer

Bacterial and eukaryotic ribosomes have significant structural differences.

Question 19

A silent mutation occurs when:

Accepted Answer

A nucleotide-pair substitution does not change the amino acid due to redundancy in the genetic code.

Question 20

Rank the following mutations from most severe to least severe effect on protein function: 1. Silent, 2. Nonsense, 3. Missense, 4. Three nucleotide deletion, 5. One nucleotide insertion.

Accepted Answer

5 (One nucleotide insertion), 2 (Nonsense), 3 (Missense), 4 (Three nucleotide deletion), 1 (Silent)

Lecture 26: Gene Expression: Transcription and Translation

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Study guide - Flashcard