Gene Mutation, Transposable Elements and DNA Repair

Question 1

Mutation

Answer 1

Heritable change in genetic information.

Question 2

Somatic Mutation

Answer 2

Mutation that arises in somatic cells and does not give rise to gametes.

Question 3

Germ Line Mutation

Answer 3

Mutation in a germ-line cell (one that gives rise to gametes).

Question 4

Gene Mutation

Answer 4

Mutation that affects a single gene or locus.

Question 5

Base Substitution

Answer 5

Mutation in which a single pair of bases in DNA is altered.

Question 6

Frameshift Mutation

Answer 6

Mutation that alters the reading frame of a gene.

Question 7

Transversion

Answer 7

Base substitution in which a purine is replaced by a pyrimidine, or a pyrimidine is replaced by a purine.

Question 8

Transition

Answer 8

Base substitution in which a purine is replaced by a different purine, or a pyrimidine is replaced by a different pyrimidine.

Question 9

Insertion

Answer 9

Mutation in which one or more nucleotide pairs are added to a DNA sequence.

Question 10

Deletion

Answer 10

Mutation in which one or more nucleotides are deleted from a DNA sequence.

Question 11

Reverse Mutation (Reversion)

Answer 11

Mutation that changes a mutant phenotype back into the wild type.

Question 12

In Frame Insertion

Answer 12

Insertion of some multiple of three nucleotides that do not alter the reading frame of the gene.

Question 13

Forward Mutation

Answer 13

Mutation that alters a wild-type phenotype.

Question 14

Expanding Nucleotide Repeat

Answer 14

Type of mutation in which the number of copies of a set of nucleotides (most often three nucleotides) increases in succeeding generations.

Question 15

Neutral Mutation

Answer 15

Mutation that changes the amino acid sequence of a protein but does not alter the function of the protein.

Question 16

Nonsense Mutation

Answer 16

Mutation that changes a sense codon (one that specifies an amino acid) into a stop codon (one that terminates translation).

Question 17

Loss Of Function Mutation

Answer 17

Mutation that causes the complete or partial absence of normal function.

Question 18

Silent Mutation

Answer 18

Change in the nucleotide sequence of DNA that does not alter the amino acid sequence of a protein.

Question 19

Gain Of Function Mutation

Answer 19

Mutation that causes the cell to produce a protein or gene product whose function is not normally present; the result could be an entirely new gene product or one produced in an inappropriate tissue or at an inappropriate time in development.

Question 20

Spontaneous Mutation

Answer 20

Mutation that arises from natural changes in DNA structure or from errors in replication.

Question 21

Lethal Mutation

Answer 21

Mutation that causes premature death.

Question 22

Mutation Rate

Answer 22

Frequency with which a wild-type allele changes to a mutant allele; generally expressed as the number of mutations per biological unit (i.e., mutations per cell division, per gamete, or per round of replication).

Question 23

Incorporated Error

Answer 23

Incorporation of a damaged nucleotide or mismatched base pair into a DNA molecule.

Question 24

Induced Mutation

Answer 24

Mutation that results from environmental agents, such as chemicals or radiation.

Question 25

Unequal Crossing Over

Answer 25

Misalignment of the two DNA molecules during crossing over, resulting in one DNA molecule with an insertion and the other with a deletion.

Question 26

Strand Slippage

Answer 26

Slipping of the template and newly synthesized strands in replication in which one of the strands loops out from the other and nucleotides are inserted or deleted on the newly synthesized strand.

Question 27

Deamination

Answer 27

Loss of an amino group NH2 from a base.

Question 28

Depurination

Answer 28

Break in the covalent bond connecting a purine base to the 1’-carbon atom of deoxyribose sugar, resulting in the loss of the purine base.

Question 29

Replicated Error

Answer 29

An incorporated error that is replicated, leading to a permanent mutation.

Question 30

Intercalating Agent

Answer 30

Molecule that is the approximately same size as a nucleotide and may become sandwiched between adjacent bases in DNA, distorting the three-dimensional structure of the DNA helix and causing single-nucleotide insertions and deletions in replication.

Question 31

Pyrimidine Dimer

Answer 31

Structure in which a bond forms between two adjacent pyrimidine molecules on the same strand of DNA; distorts the normal configuration of the DNA molecule and often blocks replication.

Question 32

Mutagen

Answer 32

Any environmental agent that significantly increases the rate of mutation above the spontaneous rate.

Question 33

Alkylating Agents

Answer 33

A chemical that can add a methyl (CH3) group to a nucleotide.

Question 34

Base Analog

Answer 34

Chemical substance that has a structure similar to that of one of the four standard nitrogenous bases of DNA and may be incorporated into newly synthesized DNA molecules in replication.

Question 35

Terminal Inverted Repeat

Answer 35

Sequences found at both ends of a transposable element that are inverted complements of one another.

Question 36

Transposition

Answer 36

Movement of a transposable element from one location to another.

Question 37

Ames Test

Answer 37

Test in which special strains of bacteria are used to evaluate the potential of chemicals to cause cancer.

Question 38

Flanking Direct Repeat

Answer 38

Short, directly repeated sequence produced on either side of a transposable element when the element inserts into DNA.

Question 39

Transposable Element

Answer 39

DNA sequence capable of moving from one site to another within the genome through a mechanism that differs from that of homologous recombination.

Question 40

DNA Transposon

Answer 40

Transposable element that transposes as DNA.

Question 41

retrotransposon

Answer 41

Type of transposable element in eukaryotic cells that possesses some characteristics of retroviruses and transposes through an RNA intermediate.

Question 42

SOS system

Answer 42

System of proteins and enzymes that allows a cell to replicate its DNA in the presence of a distortion in DNA structure; makes numerous mistakes in replication and increases the rate of mutation.

Question 43

Mistmatch Repair

Answer 43

Process that corrects mismatched nucleotides in DNA after replication has been completed. Enzymes excise incorrectly paired nucleotides from the newly synthesized strand and use the original nucleotide strand as a template for replacing them.

Question 44

Direct repair

Answer 44

DNA repair in which modified bases are changed back into their original structures.

Question 45

base-excision repair

Answer 45

DNA repair that first excises modified bases and then replaces the entire nucleotide.

Question 46

nucleotide-excision repair

Answer 46

DNA repair that removes bulky DNA lesions and other types of DNA damage.