Question 1

A gene has the following coding strand sequence: 5'-ATG GGG CCC AAT GAA-3'. What is the corresponding mRNA sequence, and what is the resulting amino acid sequence?

Accepted Answer

mRNA: 5'-AUG GGG CCC AAU GAA-3'; Protein: Met-Gly-Pro-Asn-Glu

Question 2

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

Accepted Answer

Most amino acids are encoded by more than one codon.

Question 3

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

Accepted Answer

They attach amino acids to their corresponding tRNAs.

Question 4

A tRNA with the anticodon 3'-UAI-5' can recognize which mRNA codons due to wobble base pairing?

Accepted Answer

AUC, AUU, AUA

Question 5

Which of the following post-translational modifications is most likely to regulate protein activity by adding a phosphate group?

Accepted Answer

Phosphorylation

Question 6

During translation, which direction is the mRNA read by the ribosome?

Accepted Answer

5' to 3'

Question 7

A mutation changes the codon GAA to GAG in an mRNA. Both codons specify glutamic acid. What type of mutation is this?

Accepted Answer

Silent mutation

Question 8

Which of the following best explains why the genetic code is described as 'universal'?

Accepted Answer

All organisms use the same codons for the same amino acids, with very few exceptions.

Question 9

If a protein is destined for secretion from a eukaryotic cell, which pathway does it most likely follow?

Accepted Answer

Translation on the rough ER, passage through the Golgi, then secretion

Question 10

Which of the following is a direct result of the wobble hypothesis in tRNA-codon pairing?

Accepted Answer

A single tRNA can recognize multiple codons for the same amino acid.

Question 11

A patient has a mutation that prevents the removal of the N-terminal signal sequence from a secreted protein. What is the most likely consequence?

Accepted Answer

The protein may not be properly secreted or processed.

Question 12

Which of the following best describes the relationship between codons and anticodons during translation?

Accepted Answer

They are antiparallel and complementary.

Question 13

Which of the following modifications is most likely to occur in the Golgi apparatus?

Accepted Answer

Glycosylation of proteins

Question 14

A tRNA has the anticodon 3'-CCG-5'. Which mRNA codon does it recognize, and which amino acid will be added?

Accepted Answer

5'-GGC-3'; Glycine

Question 15

Which of the following equations correctly represents the reaction catalyzed by aminoacyl-tRNA synthetase?

Accepted Answer

$$\mathrm{Amino\ acid} + \mathrm{tRNA} + \mathrm{ATP} \rightarrow \mathrm{Aminoacyl{-}tRNA} + \mathrm{AMP} + \mathrm{PP_i}$$

Question 16

A mutation introduces a premature stop codon (UAG) in the middle of a gene. What is the most likely effect on the protein product?

Accepted Answer

The protein will be truncated and likely nonfunctional.

Question 17

Which of the following best explains why post-translational modifications are important for protein function?

Accepted Answer

They allow proteins to fold, localize, and function properly.

Question 18

Which of the following codons is a start codon in eukaryotes, and what amino acid does it encode?

Accepted Answer

AUG; Methionine

Question 19

A researcher mutates the third base of a codon from C to U, but the amino acid specified does not change. Which property of the genetic code does this illustrate?

Accepted Answer

Degeneracy

Question 20

Which of the following best describes the role of ribosomal RNA (rRNA) in translation?

Accepted Answer

It catalyzes peptide bond formation and ensures proper alignment of mRNA and tRNA.

Ch 9 art 2 for exam 2

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