Question 1

Which of the following best describes the process of transcription in eukaryotic cells?

Accepted Answer

The synthesis of an mRNA molecule from a DNA template, involving RNA polymerase and the addition of caps, tails, and splicing of introns.

Question 2

During translation, which codon signals the start of protein synthesis?

Accepted Answer

$$\mathrm{AUG}$$

Question 3

A mutation changes a codon from $$\mathrm{GAA} ($$Glu/E) to $$\mathrm{GAG} ($$Glu/E). What type of mutation is this?

Accepted Answer

Silent mutation

Question 4

If a DNA template strand reads $$3'\ \mathrm{TAC}\ 5'$$, what is the corresponding mRNA codon after transcription?

Accepted Answer

$$5'\ \mathrm{AUG}\ 3'$$

Question 5

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

Accepted Answer

The same codons specify the same amino acids in nearly all organisms.

Question 6

A point mutation in the hemoglobin gene changes a codon from $$\mathrm{GAG} ($$Glu/E) to $$\mathrm{GTG} ($$Val/V). What is the most likely effect?

Accepted Answer

A missense mutation that may alter protein function, as seen in sickle-cell anemia.

Question 7

Which of the following is NOT a step in the processing of pre-mRNA in eukaryotic cells?

Accepted Answer

Direct translation by ribosomes in the nucleus

Question 8

Given the mRNA sequence $$5'\ \mathrm{AUGGCCUAA}\ 3'$$, what is the resulting amino acid sequence?

Accepted Answer

Met-Ala-Stop

Question 9

Why do all the song titles in the exercise begin with the letter 'M'?

Accepted Answer

Because methionine (M) is always the first amino acid in translation, corresponding to the start codon $$\mathrm{AUG}.$$

Question 10

A DNA sequence is mutated by inserting an extra nucleotide. What is the most likely result?

Accepted Answer

A frameshift mutation

Question 11

Which enzyme is responsible for synthesizing mRNA from a DNA template during transcription?

Accepted Answer

RNA polymerase

Question 12

If the mRNA codon $$\mathrm{UAA} is $$encountered during translation, what happens?

Accepted Answer

Translation terminates because $$\mathrm{UAA} is a $$stop codon.

Question 13

Which of the following best describes the relationship between codons and amino acids?

Accepted Answer

Each codon is a sequence of three nucleotides that specifies a single amino acid.

Question 14

A patient has a mutation in the promoter region of a gene. What is the most likely effect?

Accepted Answer

The gene may not be transcribed at all, affecting protein production.

Question 15

Which of the following is a real-world example of a disease caused by a single amino acid substitution?

Accepted Answer

Sickle-cell anemia caused by a substitution of valine for glutamic acid in hemoglobin.

Question 16

Which of the following best explains why different DNA sequences can code for the same protein sequence?

Accepted Answer

There are multiple codons for most amino acids (degeneracy of the code).

Question 17

A mutation changes a codon from $$\mathrm{UAC} ($$Tyr/Y) to $$\mathrm{UAA} ($$Stop). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 18

Which of the following steps occurs in the cytoplasm of a eukaryotic cell?

Accepted Answer

Translation of mRNA to protein

Question 19

If a gene contains 18 nucleotides (including the stop codon), how many amino acids will the resulting peptide contain?

Accepted Answer

6

Question 20

Which of the following best describes the role of tRNA during translation?

Accepted Answer

tRNA brings amino acids to the ribosome, matching its anticodon to the mRNA codon.

Study Guide: DNA, Transcription, Translation, and Mutations

Study Guide - Practice Questions