Unit 2: Sources of genetic variation

Question 1

Mutation

Answer 1

An inherited change in genetic information

Question 2

An inherited change in genetic information

Answer 2

Mutation

Question 3

Mutations are a source of _______ and _______

Answer 3

genetic variation; diseases

Question 4

How are mutations used to help in understanding basic biological processes? What is this technique called?

Answer 4

Studying mutations that disrupt normal processes often leads to the identification of genes that normally play a role in the process and can help in understanding the molecular details of a process. This technique is called genetic dissection.

Question 5

Somatic mutations

Answer 5

Mutations which arise in somatic (body) tissues. It’s the basis for cancers.

Question 6

germ-line mutation

Answer 6

Mutations that arise in cells that ultimately produce gametes

Question 7

gene mutation

Answer 7

Mutations that arise within a single gene

Question 8

base substitution

Answer 8

The simplest type of gene mutation that is the alteration of a single nucleotide in DNA

Question 9

transition

Answer 9

A purine is replaced by another purine. Same for pyrimidines.

Question 10

transversion

Answer 10

A purine is replaced by a pyrimidine or vice versa.

Question 11

insertion

Answer 11

The addition of one or more nucleotide pairs

Question 12

deletion

Answer 12

The removal of one or more nucleotide pairs

Question 13

frameshift mutation

Answer 13

Changes in the reading frame of a gene

Question 14

in-frame insertion/deletion

Answer 14

Mutations not affecting the reading frame. Consist of insertions or deletions occurring in multiples of three.

Question 15

expanding nucleotide repeat

Answer 15

Mutations in which the number of copies of a set of nucleotides increases in number.

Question 16

forward mutation

Answer 16

A mutation that alters a wild type phenotype

Question 17

reverse mutation

Answer 17

A change from the mutant phenotype back into the wild type phenotype

Question 18

missense mutation

Answer 18

A base substitution that results in a different amino acid in the protein

Question 19

nonsense mutation

Answer 19

A mutation that changes a sense codon (one that specifies an amino acid) into a nonsense codon (one that terminates translation).

Question 20

silent mutation

Answer 20

A mutation that changes a codon to another codon that specifies the same amino acid

Question 21

neutral mutation

Answer 21

A missense mutation that alters the amino acid sequence of the protein but does not change its function

Question 22

Loss-of-function mutations

Answer 22

Mutations that cause the complete loss or partial absence of normal protein function

Question 23

Gain-of-function mutations

Answer 23

Mutations which produce an entirely new trait or cause a trait to appear in the wrong place or the wrong time

Question 24

Conditional mutations

Answer 24

Mutations expressed only under certain conditions

Question 25

Lethal mutations

Answer 25

Mutations that cause premature death

Question 26

Suppressor mutation

Answer 26

A genetic change that hides or suppresses the effect of another mutation

Question 27

Intragenic suppressor mutation

Answer 27

A suppressor mutation in the same gene as that being suppressed

Question 28

Intergenic suppressor mutation

Answer 28

A suppressor mutation in a different gene as that being suppressed

Question 29

Mutation rate

Answer 29

The frequency with which a wild-type allele at a locus changes into a mutant allele

Question 30

3 factors that affect mutation rate

Answer 30

1) The frequency with which the change will take place in DNA
2) The probability that a mutation will be repaired
3) The probability that a mutation will be recognized and recorded

Question 31

Adaptive mutation

Answer 31

The process where stressful environments induce mutations so the species can survive

Question 32

Spontaneous mutations

Answer 32

mutations that occur under normal conditions

Question 33

Induced mutations

Answer 33

Mutations that result from changes caused by environmental chemicals or radiation