Alberts, Ch 5 - DNA Replication, Repair and Recombination

Question 1

Base excision repair

Answer 1

DNA repair pathway where single faulty base is removed from DNA helix and replaced

Question 2

Clamp loader

Answer 2

protein complex that utilizes ATP hydrolysis to load sliding clamp on to a primer-template junction in DNA replication

Question 3

DNA helicase

Answer 3

enzyme that is involved in opening DNA helix into its single strands for DNA replication

Question 4

DNA ligase

Answer 4

enzyme that joins ends of two strands of DNA together with covalent bonds to make a continuous DNA strand

Question 5

DNA polymerase

Answer 5

enzyme that synthesizes DNA by joining nucleotides together using DNA template as a guide

Question 6

DNA primase

Answer 6

enzyme that synthesizes a short strand of RNA on DNA template producing a primer for DNA synthesis

Question 7

DNA repair

Answer 7

set of processes for repairing the many accidental lesions that occur continually in DNA

Question 8

DNA topoisomerase

Answer 8

enzyme that binds to DNA and reversibly breaks a phosphodiester bond in one or both strands

Question 9

DNA topoisomerase I

Answer 9

creates transient single strand breaks allowing double helix to swivel and relieving superhelical tension

Question 10

DNA topoisomerase II

Answer 10

creates transient double-strand breaks, allowing one double helix to pass through another removing a tangle

Question 11

Gene conversion

Answer 11

process by which DNA sequence information can be transferred from a DNA helix to another DNA helix

Question 12

Germ cell

Answer 12

a cell in germ line of organism, includes haploid gametes and their specified diploid precursor cells, contribute to formation of new generation of organisms

Question 13

Histone chaperone

Answer 13

protein that binds free histones, releasing them once they have been incorporated into newly replicated chromatin

Question 14

Holliday junction

Answer 14

x-shaped structure observed in DNA undergoing recombination, two DNA molecules are held together at site of crossing-over

Question 15

Homologous recombination

Answer 15

genetic exchange between a pair of identical or very similar DNA sequences, DNA repair mechanism for double-strand breaks

Question 16

Hybridization

Answer 16

process where two complementary nucleic acid strands form a base-paired duplex molecules

Question 17

Lagging strand

Answer 17

one of two newly synthesized strands of DNA found at replication fork, is made in discontinuous lengths that are later joined covalently

Question 18

Leading strand

Answer 18

one of two newly synthesized strands of DNA found at replication fork, is made in by continuous synthesis in 5’ to 3’ direction

Question 19

Loss of heterozygosity

Answer 19

result of errant homologous recombination that uses homolog from the other parent instead of sister chromatid as template

Question 20

Mutation rate

Answer 20

rate at which changes occur in DNA sequences

Question 21

Nonhomologous end joining

Answer 21

DNA repair mechanism for double-strand breaks in which broken ends of DNA are brought together and rejoined by DNA ligation, generally with loss of one or more nucleotides at site of joining

Question 22

Nucleotide excision repair

Answer 22

type of DNA repair that corrects damage of the DNA double helix, such as that caused by chemicals or UV light, by cutting out damaged region on one strand and resynthesizing it using undamaged strand as template

Question 23

Origin recognition complex (ORC)

Answer 23

large protein complex that is bound to DNA at origins of replication in eukaryotic chromosomes throughout cell cycle

Question 24

Rad51

Answer 24

eukaryotic protein that catalyzes synapsis of DNA strands during genetic recombination

Question 25

RecA

Answer 25

protein in E. coli that catalyzes synapsis of DNA strands during genetic recombination

Question 26

Replication fork

Answer 26

Y-shaped region of replication on DNA molecule at which two strands of DNA are being separated and daughter strands are being formed

Question 27

Replication origin

Answer 27

location on a DNA molecule at which duplication of DNA begins

Question 28

RNA primer

Answer 28

short stretch of RNA synthesized on DNA template, required by DNA polymerases to start their DNA synthesis

Question 29

S phase

Answer 29

period of eukaryotic cell cycle in which DNA is synthesized

Question 30

Single-strand DNA-binding (SSB) protein

Answer 30

protein that binds to single strands of opened-up DNA double helix, preventing helical structures from reforming while DNA is being replicated

Question 31

Sliding clamp

Answer 31

protein complex that holds DNA polymerase on DNA during DNA replication

Question 32

Somatic cell

Answer 32

any cell other than cells of the germ line

Question 33

Strand exchange

Answer 33

reaction in which one of the duplex DNA molecule penetrates another duplex and searches it for homologous sequences through base-pairing

Question 34

Telomere

Answer 34

end of chromosome, associated with a characteristic DNA sequences that is replicated in a special way, counteracts tendency of chromosome to shorten with each round of replication

Question 35

Allele

Answer 35

one of several alternative forms of a gene

Question 36

strand-directed mismatch repair

Answer 36

proofreading system that removes DNA replication errors missed by DNA polymerase proofreading exonuclease, detects potential for DNA helix distortion from noncomplementary base pairs then recognizes and excises mismatch in the newly synthesized strand and resynthesizes the excised segment using the old strand as a template