Question 1

Which of the following best describes an allele at the molecular level?

Accepted Answer

An allele is a form of a gene defined by a specific DNA sequence variant.

Question 2

A substitution mutation is best described as:

Accepted Answer

A single nucleotide change in the DNA sequence.

Question 3

Which type of mutation leads to a single amino acid change in the encoded protein?

Accepted Answer

Missense mutation

Question 4

A null allele is characterized by:

Accepted Answer

No functional activity of the gene product.

Question 5

Which of the following is an example of a conditional allele?

Accepted Answer

A temperature-sensitive allele that is functional only at lower temperatures.

Question 6

Dominant negative alleles most commonly occur in genes encoding:

Accepted Answer

Multimeric proteins

Question 7

Which of the following best describes a gain-of-function neomorphic allele?

Accepted Answer

An allele whose product has a new functional activity or is expressed in a new place/time.

Question 8

A hypomorphic allele is defined as:

Accepted Answer

An allele with reduced functional activity of its product.

Question 9

Which mutation type is most likely to result in a premature stop codon?

Accepted Answer

Nonsense mutation

Question 10

A wild type allele is best described as:

Accepted Answer

The most common functional allele in a population.

Question 11

Which of the following is a real-world example of a null allele phenotype?

Accepted Answer

Albinism in vertebrates due to loss of tyrosinase function.

Question 12

If a gene product is produced only when the gene is transcribed and translated, this is referred to as:

Accepted Answer

Gene expression

Question 13

Which of the following best describes a frameshift mutation?

Accepted Answer

An insertion or deletion that alters reading frame and changes all amino acids downstream.

Question 14

A dominant negative allele produces a product that:

Accepted Answer

Interferes with the activity of a wild-type allele product from the same gene.

Question 15

Which of the following is true about mutation and function?

Accepted Answer

Mutation does not imply any change in function; it just means a change in DNA sequence.

Question 16

A temperature-sensitive allele of tyrosinase in rabbits results in which phenotype?

Accepted Answer

Pigmentation only in cooler body regions, such as ears and feet.

Question 17

Which equation would you use to compare two DNA sequences for allele variation?

Accepted Answer

$	ext{Sequence alignment score} = \sum_{i=1}^{n} s(x_i, y_i)$

Question 18

Which of the following is a real-world example of a hypomorphic allele?

Accepted Answer

Chinchilla rabbits with lighter fur due to reduced melanin synthesis.

Question 19

Which of the following is NOT a type of mutation described in the study materials?

Accepted Answer

Epigenetic mutation

Question 20

A gain-of-function hypermorphic allele is best exemplified by which scenario?

Accepted Answer

An allele that produces excess Agouti protein, leading to yellow fur in mice.

Alleles and Allelic Variation: Types, Mechanisms, and Phenotypic Effects

Study Guide - Practice Questions