Question 1

Which of the following statements best explains why transcription and translation can occur simultaneously in prokaryotic cells but not in eukaryotic cells?

Accepted Answer

Prokaryotic cells lack a nuclear envelope, allowing ribosomes to access mRNA as it is being transcribed.

Question 2

A mutation changes the DNA sequence from 5'-ATG GAA TGA-3' to 5'-ATG GAA TGG-3'. Using the genetic code, what is the most likely effect on the resulting protein?

Accepted Answer

The protein will be longer because a stop codon is replaced by a codon for tryptophan.

Question 3

Which of the following modifications occurs to eukaryotic pre-mRNA before it leaves the nucleus?

Accepted Answer

Addition of a 5' cap and a poly-A tail

Question 4

A scientist isolates a eukaryotic mRNA and finds that it contains both coding and noncoding regions. What process likely failed during RNA processing?

Accepted Answer

RNA splicing

Question 5

Which enzyme is responsible for attaching the correct amino acid to its corresponding tRNA during translation?

Accepted Answer

Aminoacyl-tRNA synthetase

Question 6

If a DNA template strand has the sequence 3'-TAC GGA CCT-5', what is the corresponding mRNA sequence produced during transcription?

Accepted Answer

$$5'	ext{AUG GGU GGA}\ 3'$$

Question 7

Which of the following best describes a missense mutation?

Accepted Answer

A point mutation that results in a codon coding for a different amino acid

Question 8

What is the role of the signal-recognition particle (SRP) during translation in eukaryotic cells?

Accepted Answer

It directs ribosomes synthesizing proteins with a signal peptide to the endoplasmic reticulum.

Question 9

Which of the following statements about the genetic code is correct?

Accepted Answer

It is redundant but not ambiguous; each codon specifies only one amino acid.

Question 10

A mutation causes the insertion of two nucleotides into the coding region of a gene. What is the most likely consequence?

Accepted Answer

A frameshift mutation, altering the reading frame and likely resulting in a nonfunctional protein

Question 11

Which of the following best explains why alternative RNA splicing can increase the diversity of proteins produced by a single gene?

Accepted Answer

Different combinations of exons can be joined to produce multiple mRNA variants from one gene.

Question 12

During translation, which site on the ribosome holds the tRNA carrying the growing polypeptide chain?

Accepted Answer

P site

Question 13

Which of the following is a function of the 5' cap and poly-A tail added to eukaryotic mRNA?

Accepted Answer

They protect mRNA from degradation and help ribosomes recognize the mRNA.

Question 14

Which of the following is true about ribozymes?

Accepted Answer

They are RNA molecules that can catalyze chemical reactions, such as RNA splicing.

Question 15

A researcher introduces a gene from a jellyfish into a mosquito, and the mosquito expresses the gene. What does this demonstrate about the genetic code?

Accepted Answer

The genetic code is nearly universal among all organisms.

Question 16

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

$$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$

Question 17

Which of the following is NOT a post-translational modification?

Accepted Answer

Addition of a 5' cap to mRNA

Question 18

Which of the following is a likely result of a nonsense mutation in a gene?

Accepted Answer

A shortened, likely nonfunctional protein due to a premature stop codon

Question 19

Which of the following best describes the function of spliceosomes?

Accepted Answer

They remove introns from pre-mRNA and join exons together.

Question 20

A chemical mutagen causes a single nucleotide substitution in a gene. Which of the following outcomes is NOT possible?

Accepted Answer

A frameshift mutation

Gene Expression: From Gene to Protein (Transcription, Translation, and Mutations)

Study Guide - Practice Questions

Study Guide - Flashcards