Q: Which enzyme is responsible for attaching the correct amino acid to its corresponding tRNA, and what is the reaction it catalyzes?

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

Question 1

Which of the following statements best describes the directionality of RNA synthesis during transcription?

Accepted Answer

RNA is synthesized in the 5' to 3' direction, using the DNA template strand in the 3' to 5' direction.

Question 2

Which of the following is a unique property of RNA polymerase compared to DNA polymerase?

Accepted Answer

RNA polymerase can initiate synthesis of a new strand in the absence of a primer.

Question 3

A mutation in the TATA box of a gene's promoter is most likely to affect which process?

Accepted Answer

The binding of RNA polymerase and initiation of transcription

Question 4

Which of the following post-transcriptional modifications is essential for protecting mRNA from degradation and facilitating ribosome binding?

Accepted Answer

Addition of a 5' cap

Question 5

During translation, which site on the ribosome does the initiator tRNA first bind to?

Accepted Answer

P (peptidyl) site

Question 6

A patient is diagnosed with sickle cell anemia, which is caused by a single nucleotide substitution in the hemoglobin gene. What type of mutation is this?

Accepted Answer

Missense mutation

Question 7

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

Accepted Answer

Multiple codons can specify the same amino acid.

Question 8

Which enzyme is responsible for attaching the correct amino acid to its corresponding tRNA, and what is the reaction it catalyzes?

Accepted Answer

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

Question 9

Which of the following post-translational modifications is most directly involved in targeting proteins for degradation by the proteasome?

Accepted Answer

Ubiquitination

Question 10

A frameshift mutation in a gene is most likely to result from which of the following genetic changes?

Accepted Answer

Insertion or deletion of one or two nucleotides

Question 11

Which of the following best describes the function of the 3' CCA end of tRNA?

Accepted Answer

It is the site where the amino acid is covalently attached.

Question 12

Which of the following is a function of glycosylation as a post-translational modification?

Accepted Answer

It assists in protein folding and enhances stability.

Question 13

A researcher mutates the CAAT box in a gene's promoter region. What is the most likely effect on gene expression?

Accepted Answer

Decreased recruitment of transcription factors, leading to reduced transcription

Question 14

Which of the following statements about the differences between prokaryotic and eukaryotic transcription is correct?

Accepted Answer

Eukaryotic mRNA undergoes extensive post-transcriptional modifications, while prokaryotic mRNA does not.

Question 15

Which of the following best describes the role of the spliceosome?

Accepted Answer

It removes introns from pre-mRNA and joins exons together.

Question 16

A patient has a mutation that prevents the addition of a poly-A tail to mRNA. Which of the following is the most likely consequence?

Accepted Answer

The mRNA will be rapidly degraded and have reduced stability.

Question 17

Which of the following post-translational modifications is most directly involved in regulating gene expression by altering chromatin structure?

Accepted Answer

Acetylation of histones

Question 18

Which of the following is a direct biological consequence of gamma-carboxylation of glutamic acid residues in proteins?

Accepted Answer

Enhanced calcium binding, crucial for blood coagulation

Question 19

A mutation introduces a premature stop codon into the coding sequence of a gene. What type of mutation is this, and what is the likely effect on the protein product?

Accepted Answer

Nonsense mutation; the protein is truncated

Question 20

Which of the following best explains why the A1C test is useful for monitoring diabetes management?

Accepted Answer

It reflects the average blood glucose levels over the past 2-3 months.

Gene Transcription and Translation: Biochemistry Study Notes

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