DNA Damage, Repair, and Mutagenesis

Question 1

Locus

Answer 1

A segment of DNA occupying a particular position or location on a chromosome

Question 2

Alleles

Answer 2

Alternative versions of the DNA sequence at a locus

Question 3

Wild-type

Answer 3

An allele present in more than half of the individuals in a population

Question 4

Varient (or mutant)

Answer 4

An allele that differs from the wild-type allele because of the presence of a mutation

Question 5

Mutation

Answer 5

Permanent change in the nucleotide sequence or arrangement of DNA

Question 6

Polymorphism

Answer 6

The occurrence of two or more alternative alleles at a locus, each at a frequency greater than 1% within a population

Question 7

Rare Variant

Answer 7

Variant allele that occurs within a population at a frequency <1%

Question 8

SNPs

Answer 8

Single Nucleotide Polymorphism

Question 9

Chromosome Mutation

Answer 9

Mutations that leave chromosomes intact but change the number of chromosomes in a cell

Question 10

Regional or Subchromosomal Mutation

Answer 10

Mutation that changes only a portion of a chromosome and might involve a change in the copy number of a subchromosomal segment or a structural rearrangement involving parts of one or more chromosomes

Question 11

Gene Mutation

Answer 11

Alterations in the sequence of DNA, involving the substitution, deletion, or insertion of DNA (single nucleotide up to 100 kilobases)

Question 12

Transition Mutation

Answer 12

Changes one purine for a different purine or a pyrimidine for a different pyrimidine

Question 13

Transversion Mutation

Answer 13

Changes a purine to a pyrimidine or vise versa

Question 14

Missense Mutation

Answer 14

A point mutation that alters the coding strand of the gene to specify a different amino acid

Question 15

Nonsense Mutation

Answer 15

A point mutation in a DNA sequence that causes the normal codon for an amino acid to be replaced with a termination (“stop”) codon

Question 16

RNA Splicing Mutation

Answer 16

A point mutation that interferes with the normal process of mRNA splicing

Can interfere with or abolish normal splicing or create alternative splicing sites that compete with normal sites during RNA processing

Question 17

Frameshift Mutation

Answer 17

An insertion/deletion within the coding sequence of a number of bases that is NOT a multiple of 3

From the point of the insertion or deletion, a different sequence of codons is generated that encodes incorrect amino acids and can insert a premature stop codon.

Question 18

Codon Insertin/Deletion

Answer 18

An insertion/deletion of a number of bases that IS a multiple of 3

Simple insertion or deletion of the corresponding amino acids; effects on protein product can be highly variable

Question 19

Larger duplications, deletions, and inversions

Answer 19

Duplications/deletions/inversions of a larger segment of a single chromosome are usually the result of homologous recombination between DNA segments with high sequence homology

Question 20

Insertion of Repeat Elements

Answer 20

Insertion of repeat elements within the coding sequence interrupts and destroys information leading to gene product

Question 21

Haploinsufficiency

Answer 21

Inability of a single copy of the genetic material to carry out the functions normally performed by two copies

Question 22

Dominant Negative

Answer 22

A disease-causing allele that disrupts the function of a wild-type allele in the same cell

Question 23

Exogenous

Answer 23

External factors

Question 24

Endogenous

Answer 24

Internal cause or origin