Question 1

Which of the following statements best explains why eukaryotic mRNAs are generally more stable than prokaryotic mRNAs?

Accepted Answer

Eukaryotic mRNAs have a 5' cap and a 3' polyA tail that protect them from degradation.

Question 2

A mutation in the Shine-Dalgarno sequence of a prokaryotic mRNA would most likely result in which of the following?

Accepted Answer

Impaired binding of the ribosome to the mRNA, reducing translation efficiency.

Question 3

Which antibiotic specifically inhibits the peptidyltransferase reaction in prokaryotes?

Accepted Answer

Chloramphenicol

Question 4

In the context of the 'one gene:one polypeptide' hypothesis, which of the following best explains the molecular basis of sickle cell anemia?

Accepted Answer

A single nucleotide substitution in the gene encoding the β-globin chain leads to a single amino acid change from Glu to Val.

Question 5

Which of the following best describes the difference between polypeptides and proteins?

Accepted Answer

Polypeptides are linear chains of amino acids, while proteins are folded, functional forms of polypeptides.

Question 6

Which of the following is a key feature of the closed-loop model of eukaryotic translation?

Accepted Answer

The 3' polyA tail interacts with the 5' cap via protein factors, forming a loop that enhances translation efficiency.

Question 7

A patient is treated with an antibiotic that blocks the translocation reaction during protein synthesis. Which of the following antibiotics is most likely responsible for this effect in bacteria?

Accepted Answer

Erythromycin

Question 8

Which of the following best describes the secondary structure of a protein?

Accepted Answer

Regular folding patterns such as $$\alpha-$$helices and $$\beta-$$pleated sheets stabilized by hydrogen bonds.

Question 9

Which of the following is true regarding the initiation of translation in eukaryotes?

Accepted Answer

The ribosome recognizes the 5' cap and scans for the first AUG codon within a Kozak sequence.

Question 10

Which of the following best explains why polyribosomes (polysomes) are advantageous for the cell?

Accepted Answer

They allow multiple ribosomes to translate a single mRNA simultaneously, increasing protein synthesis efficiency.

Question 11

A mutation in a gene results in a protein that is missing its quaternary structure. Which of the following is the most likely consequence?

Accepted Answer

The protein cannot assemble with other polypeptide chains, potentially losing its function.

Question 12

Which of the following best describes the experimental approach used by Beadle and Tatum to support the 'one gene:one enzyme' hypothesis?

Accepted Answer

They induced mutations in Neurospora and identified mutants that could not grow on minimal medium unless supplemented with specific nutrients.

Question 13

Which of the following is a correct statement about the structure of an amino acid?

Accepted Answer

It contains a central $$\alpha-$$carbon bonded to an amino group, a carboxyl group, a hydrogen atom, and a variable side chain (R group).

Question 14

Which of the following best explains why a single base substitution in the β-globin gene can cause sickle cell anemia?

Accepted Answer

The substitution changes the codon from GAG (Glu) to GTG (Val), altering the protein's structure and function.

Question 15

Which of the following best describes the role of hydrogen bonds in the formation of an $$\alpha-$$helix?

Accepted Answer

Hydrogen bonds form between the carbonyl oxygen of one amino acid and the amide hydrogen of another four residues away.

Question 16

Which of the following statements about prokaryotic and eukaryotic translation is correct?

Accepted Answer

In prokaryotes, transcription and translation are coupled, while in eukaryotes, they are separated by the nuclear envelope.

Question 17

A scientist discovers a new antibiotic that causes premature release of the polypeptide chain during translation in both bacteria and eukaryotes. Which known inhibitor does this most closely resemble?

Accepted Answer

Puromycin

Question 18

Which of the following best describes the quaternary structure of a protein?

Accepted Answer

The arrangement and interaction of multiple polypeptide subunits in a multi-subunit protein.

Translation and Protein Structure: From Genes to Functional Proteins

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