Question 1

Which of the following modifications occurs at the 5' end of a pre-mRNA molecule during processing in eukaryotic cells?

Accepted Answer

Addition of a 5' cap

Question 2

What is the primary function of the poly-A tail added to the 3' end of pre-mRNA?

Accepted Answer

Facilitates export of mRNA to the cytoplasm

Question 3

During RNA splicing, which of the following components is responsible for recognizing splice sites and removing introns?

Accepted Answer

Spliceosomes

Question 4

Alternative splicing allows for which of the following outcomes?

Accepted Answer

A single gene encoding multiple polypeptides

Question 5

Which statement best describes a codon?

Accepted Answer

A sequence of three nucleotides in mRNA that codes for a specific amino acid

Question 6

If the DNA template strand has the sequence 5'-TAC-3', what is the corresponding mRNA codon?

Accepted Answer

5'-AUG-3'

Question 7

How many possible codons exist in the genetic code, and how many of these code for amino acids?

Accepted Answer

$$64$$ codons, $$61$$ code for amino acids

Question 8

Which of the following best explains why the genetic code is described as 'redundant but not ambiguous'?

Accepted Answer

More than one codon can specify the same amino acid, but each codon specifies only one amino acid

Question 9

A mutation shifts the reading frame of an mRNA by one nucleotide. What is the most likely consequence?

Accepted Answer

The resulting protein will have a completely different amino acid sequence after the mutation site

Question 10

Which of the following statements about tRNA is correct?

Accepted Answer

tRNA molecules carry amino acids to the ribosome and have an anticodon that base-pairs with mRNA codons

Question 11

Which ribosomal site holds the tRNA carrying the growing polypeptide chain during translation?

Accepted Answer

P site

Question 12

During the initiation of translation, which amino acid is always the first to be incorporated into a new polypeptide in eukaryotes?

Accepted Answer

Methionine

Question 13

Which of the following events occurs during the elongation stage of translation?

Accepted Answer

Peptide bond formation between amino acids

Question 14

What is the role of GTP during translation elongation?

Accepted Answer

Provides energy for translocation and peptide bond formation

Question 15

What triggers the termination of translation in eukaryotic cells?

Accepted Answer

A stop codon enters the A site of the ribosome

Question 16

Which molecule causes the release of the newly synthesized polypeptide from the ribosome during translation termination?

Accepted Answer

Release factor

Question 17

A scientist mutates the gene encoding a spliceosome protein. Which process will most likely be directly affected?

Accepted Answer

Removal of introns from pre-mRNA

Question 18

Which of the following best describes the relationship between the template strand and the coding strand of DNA during transcription?

Accepted Answer

The template strand is used to synthesize mRNA, while the coding strand has the same sequence as mRNA except T is replaced by U

Question 19

A mutation in the polyadenylation signal of a gene would most likely affect which aspect of mRNA processing?

Accepted Answer

Addition of the poly-A tail at the 3' end

Question 20

Which of the following is a real-world consequence of errors in mRNA splicing?

Accepted Answer

Production of nonfunctional or harmful proteins, potentially leading to genetic diseases

Gene Expression: From Gene to Protein – Pre-mRNA Processing and Translation

Study Guide - Practice Questions