Question 1

Which of the following statements best describes the role of the Shine-Dalgarno sequence in prokaryotic translation initiation?

Accepted Answer

It base-pairs with a complementary sequence on rRNA to position the ribosome at the correct start site.

Question 2

A mutation changes the third nucleotide of a codon from C to U. Which property of the genetic code explains why this mutation might not change the amino acid sequence of the protein?

Accepted Answer

Degeneracy

Question 3

Which of the following best describes the chemical reaction that forms a peptide bond between two amino acids?

Accepted Answer

Condensation reaction between the carboxyl group of one amino acid and the amino group of another.

Question 4

Which of the following features is unique to the initiator tRNA used in prokaryotic translation initiation?

Accepted Answer

It is charged with N-formylmethionine.

Question 5

During translation elongation in prokaryotes, which factor is responsible for bringing charged tRNAs to the A site of the ribosome?

Accepted Answer

Elongation Factor Tu (EF-Tu)

Question 6

Which of the following statements about tRNA charging is correct?

Accepted Answer

Aminoacyl tRNA synthetases catalyze the attachment of amino acids to tRNAs.

Question 7

Which of the following is a consequence of the 'wobble' position in the genetic code?

Accepted Answer

Some tRNAs can recognize multiple codons due to relaxed base-pairing at the 3' position of the codon.

Question 8

A patient is treated with an antibiotic that specifically inhibits prokaryotic ribosomes. Which of the following processes will be most directly affected in the bacteria?

Accepted Answer

Protein synthesis (translation)

Question 9

Which level of protein structure is primarily determined by hydrogen bonding between backbone groups, resulting in alpha helices and beta sheets?

Accepted Answer

Secondary structure

Question 10

Which of the following statements about the genetic code is FALSE?

Accepted Answer

The genetic code is completely universal with no exceptions.

Question 11

Which of the following best explains why proline disrupts alpha helix formation in proteins?

Accepted Answer

Proline's side chain forms a covalent link with the amino nitrogen, preventing backbone hydrogen bonding.

Question 12

Which of the following is required for eukaryotic translation initiation but NOT for prokaryotic translation initiation?

Accepted Answer

5' methyl-guanosine cap and polyA tail

Question 13

Which of the following correctly matches the protein structure level with its description?

Accepted Answer

Tertiary structure: overall 3D folding of a single polypeptide chain

Question 14

During prokaryotic translation elongation, what is the immediate consequence of GTP hydrolysis by EF-G?

Accepted Answer

The ribosome translocates, moving the peptidyl-tRNA from the A site to the P site.

Question 15

Which of the following is TRUE regarding the polarity of polypeptides?

Accepted Answer

Polypeptides have a free N-terminus and a free C-terminus, giving them polarity.

Question 16

A mutation in the gene encoding an aminoacyl tRNA synthetase causes it to charge tRNA	extsuperscript{Phe} with leucine instead of phenylalanine. What is the most likely consequence for the cell?

Accepted Answer

Leucine will be incorporated at positions in the protein where phenylalanine should be.

Question 17

Which of the following bonds is responsible for stabilizing the tertiary structure of proteins?

Accepted Answer

Disulfide bridges, ionic bonds, hydrophobic interactions, and van der Waals forces

Question 18

Which of the following statements about ribosomes is correct?

Accepted Answer

Ribosomes catalyze peptide bond formation during translation.

Question 19

Which of the following best describes the function of release factors during translation termination in prokaryotes?

Accepted Answer

They bind to the A site and catalyze the transfer of the polypeptide to water, releasing it from the ribosome.

Protein Structure, Translation, and the Genetic Code

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