Question 1

Which of the following best describes a point mutation?

Accepted Answer

A change in a single nucleotide pair of a gene

Question 2

A single nucleotide substitution in the DNA template strand changes the codon GAG to GTG in the β-globin gene. What is the result at the protein level?

Accepted Answer

Glutamic acid is replaced by valine

Question 3

Which type of mutation is most likely to result in a nonfunctional protein when it occurs near the beginning of a coding sequence?

Accepted Answer

Nonsense mutation

Question 4

A mutation changes a codon from UAU (tyrosine) to UAA. What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 5

If a single nucleotide is inserted into the coding region of a gene, what is the most likely consequence?

Accepted Answer

A frameshift mutation will occur, altering the reading frame

Question 6

Which of the following best explains why sickle-cell disease is considered a genetic disorder?

Accepted Answer

It is caused by a point mutation that alters the structure and function of hemoglobin

Question 7

A DNA sequence 3'-TACTTGTCCGATATC-5' is mutated to 3'-TACTTGTCCAATATC-5'. What is the effect of this mutation?

Accepted Answer

It causes a frameshift mutation

Question 8

Which of the following statements about silent mutations is correct?

Accepted Answer

They do not change the amino acid sequence of the protein

Question 9

Which of the following is a possible consequence of a frameshift mutation?

Accepted Answer

Extensive missense mutations and premature termination

Question 10

A patient with neonatal diabetes is found to have a nucleotide-pair substitution in the insulin gene that does not change the amino acid sequence. What type of mutation is this?

Accepted Answer

Silent mutation

Question 11

Which of the following best describes the evolutionary significance of mutations?

Accepted Answer

They provide the raw material for natural selection by creating genetic variation

Question 12

Which of the following agents is considered a physical mutagen?

Accepted Answer

Ultraviolet (UV) light

Question 13

A chemical mutagen that resembles a normal DNA nucleotide but pairs incorrectly during replication is called:

Accepted Answer

A nucleotide analog

Question 14

Which of the following best defines a gene in modern molecular biology?

Accepted Answer

A region of DNA that can be expressed to produce a final functional product, either a polypeptide or an RNA molecule

Question 15

Which of the following is most likely to be the result of a missense mutation?

Accepted Answer

A single amino acid in the protein is changed

Question 16

A mutation in the tyrosinase gene of the Asinara donkey changes a C to a G, resulting in a histidine instead of an aspartic acid. This is an example of:

Accepted Answer

Missense mutation

Question 17

Which of the following is true about mutagens and cancer?

Accepted Answer

Most carcinogens are mutagenic, and most mutagens are carcinogenic

Question 18

If a DNA replication error is not corrected by proofreading and repair systems, what is the result?

Accepted Answer

A spontaneous mutation

Question 19

A mutation that changes a codon from AAA (lysine) to AGA (arginine) is classified as which type of mutation?

Accepted Answer

Missense mutation

Question 20

Which of the following best explains why insertions or deletions of nucleotides often have more severe effects than substitutions?

Accepted Answer

They can cause frameshift mutations, altering the reading frame for all downstream codons

Question 21

A patient’s insulin gene has a nucleotide-pair substitution that results in a stop codon in the middle of the coding sequence. What is the likely effect?

Accepted Answer

The protein will be truncated and likely nonfunctional

Mutations: Effects on Protein Structure and Function

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