$$ \text{Amino acid} + \text{tRNA} + \text{ATP} \rightarrow \text{Aminoacyl-tRNA} + \text{AMP} + \text{PP}_i $$

Question 1

Which of the following best explains why transcription and translation can be coupled in bacteria but not in eukaryotes?

Accepted Answer

Bacteria lack a nucleus, allowing ribosomes to access mRNA as it is being transcribed.

Question 2

What is the function of aminoacyl-tRNA synthetase during translation?

Accepted Answer

It catalyzes the attachment of an amino acid to its corresponding tRNA using ATP.

Question 3

A mutation in the gene encoding the Shine-Dalgarno sequence would most likely affect which process in bacteria?

Accepted Answer

Initiation of translation by preventing ribosome binding to mRNA.

Question 4

Which site on the ribosome does the initiator tRNA occupy at the start of translation in bacteria?

Accepted Answer

P site

Question 5

What is the significance of the 'wobble' position in tRNA anticodons?

Accepted Answer

It allows a single tRNA to recognize multiple codons for the same amino acid.

Question 6

During translation elongation, what is the correct sequence of events?

Accepted Answer

Aminoacyl-tRNA enters the A site, peptide bond forms, ribosome translocates.

Question 7

Which of the following statements about ribosomes is TRUE?

Accepted Answer

The ribosome is a ribozyme because its active site is composed of rRNA that catalyzes peptide bond formation.

Question 8

What happens when a stop codon is encountered during translation?

Accepted Answer

A release factor binds to the A site, hydrolyzing the bond between the polypeptide and the tRNA.

Question 9

Which of the following modifications can occur to a polypeptide after translation?

Accepted Answer

Addition of a phosphate group by an enzyme to regulate protein activity.

Question 10

A scientist isolates a mutant tRNA that cannot be charged with its amino acid. What is the most likely consequence for translation?

Accepted Answer

The corresponding codon will not be translated, leading to incomplete or faulty proteins.

Question 11

Which equation best represents the energy requirement for charging a tRNA with its amino acid?

Accepted Answer

$$ 	ext{Amino acid} + 	ext{tRNA} + 	ext{ATP} ightarrow 	ext{Aminoacyl-tRNA} + 	ext{AMP} + 	ext{PP}_i $$

Question 12

Which of the following best describes the role of molecular chaperones in protein folding?

Accepted Answer

They guide and speed up the folding of newly synthesized polypeptides.

Question 13

If a mutation prevents the addition of the CCA sequence at the 3' end of tRNA, what is the most direct effect?

Accepted Answer

The tRNA cannot be charged with an amino acid.

Question 14

Which of the following is TRUE regarding the direction of polypeptide synthesis during translation?

Accepted Answer

Amino acids are always added to the carboxyl end (C-terminus) of the growing polypeptide.

Question 15

Which of the following best describes the function of the large ribosomal subunit?

Accepted Answer

It is the site where peptide bonds are formed between amino acids.

Question 16

A patient is exposed to a toxin that inhibits elongation factors during translation. What is the most likely cellular effect?

Accepted Answer

The ribosome will be unable to move along the mRNA, stalling protein synthesis.

Question 17

Which of the following is a direct result of post-translational modification?

Accepted Answer

A protein's function or activity is altered, such as by phosphorylation.

Question 18

Which of the following best explains why there are fewer tRNAs than codons?

Accepted Answer

Wobble pairing allows some tRNAs to recognize more than one codon.

Question 19

Which of the following steps is NOT part of the three-step elongation cycle during translation?

Accepted Answer

Release factor binding to the A site.

Transcription, RNA Processing, and Translation (Part 2): Structure and Function of tRNA and Ribosomes

Study Guide - Practice Questions