Question 1

Which of the following statements best describes the universality of the genetic code?

Accepted Answer

The genetic code is nearly universal, with rare exceptions found in some prokaryotes, fungi, and protists.

Question 2

During translation, which molecule is responsible for recognizing termination codons?

Accepted Answer

Release factors (RFs)

Question 3

A mutation changes the codon $$GAA ($$glutamic acid) to $$GAG ($$also glutamic acid). What type of mutation is this?

Accepted Answer

Synonymous (silent) mutation

Question 4

Which of the following best explains the concept of 'wobble' in codon-anticodon pairing?

Accepted Answer

Wobble allows flexibility at the third position of the codon, enabling one tRNA to recognize multiple codons.

Question 5

A conservative mutation is best described as:

Accepted Answer

A mutation that changes a codon to one encoding a chemically similar amino acid, often preserving protein function.

Question 6

Which equation correctly represents the number of possible codons in the genetic code?

Accepted Answer

$$4 	imes 4 	imes 4 = 64$$

Question 7

Why can synonymous mutations sometimes affect protein function, even though they do not change the amino acid sequence?

Accepted Answer

They can alter the rate of translation due to differences in tRNA abundance, affecting protein folding.

Question 8

Which of the following is NOT a property of aminoacyl-tRNA synthetases?

Accepted Answer

They catalyze peptide bond formation during translation.

Question 9

Suppose a nonsense mutation introduces a premature stop codon in an mRNA. Which mechanism can allow translation to continue past this stop codon?

Accepted Answer

A suppressor tRNA with a mutated anticodon that recognizes the stop codon and inserts an amino acid.

Question 10

Which of the following codons is an exception to the wobble rule and does NOT allow wobble pairing?

Accepted Answer

$$AUG ($$Methionine)

Question 11

If a tRNA anticodon is $$5'-GAA-3'$$, which mRNA codon can it recognize via standard Watson-Crick base pairing?

Accepted Answer

$$5'-UUC-3'$$

Question 12

Which of the following best describes the relationship between codon usage and tRNA abundance in different organisms?

Accepted Answer

Codon usage bias reflects the abundance of corresponding tRNAs, affecting translation efficiency.

Question 13

A mutation changes the codon $$AAA ($$Lysine) to $$AGA ($$Arginine). What type of mutation is this?

Accepted Answer

Missense mutation

Question 14

Which of the following statements about suppressor tRNAs is correct?

Accepted Answer

Suppressor tRNAs can recognize mutated codons and insert amino acids, potentially restoring protein function.

Question 15

Which of the following is a consequence of the genetic code being redundant/degenerate?

Accepted Answer

Multiple codons can encode the same amino acid, allowing for silent mutations.

Question 16

A mutation in the MDR1 gene changes a codon to a rare synonymous codon. What is a possible effect?

Accepted Answer

Slower translation may alter protein folding and substrate specificity.

Question 17

Which of the following is true regarding the recognition of codons by tRNAs?

Accepted Answer

Each codon can only be recognized by tRNAs encoding the same amino acid.

Question 18

Which process is directly catalyzed by aminoacyl-tRNA synthetases?

Accepted Answer

Attachment of amino acids to tRNAs using ATP hydrolysis.

Question 19

Which of the following mutations is most likely to be classified as a polymorphism?

Accepted Answer

A synonymous mutation that does not affect viability or fertility.

Question 20

Which of the following best describes the role of release factors RF1 and RF2 in bacteria?

Accepted Answer

They recognize stop codons and promote termination of translation.

Genetic Code and Translation: Structure, Function, and Mutational Consequences

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