Alberts, Ch 5 - DNA Replication, Repair and Recombination Flashcards
Base excision repair
DNA repair pathway where single faulty base is removed from DNA helix and replaced
Clamp loader
protein complex that utilizes ATP hydrolysis to load sliding clamp on to a primer-template junction in DNA replication
DNA helicase
enzyme that is involved in opening DNA helix into its single strands for DNA replication
DNA ligase
enzyme that joins ends of two strands of DNA together with covalent bonds to make a continuous DNA strand
DNA polymerase
enzyme that synthesizes DNA by joining nucleotides together using DNA template as a guide
DNA primase
enzyme that synthesizes a short strand of RNA on DNA template producing a primer for DNA synthesis
DNA repair
set of processes for repairing the many accidental lesions that occur continually in DNA
DNA topoisomerase
enzyme that binds to DNA and reversibly breaks a phosphodiester bond in one or both strands
DNA topoisomerase I
creates transient single strand breaks allowing double helix to swivel and relieving superhelical tension
DNA topoisomerase II
creates transient double-strand breaks, allowing one double helix to pass through another removing a tangle
Gene conversion
process by which DNA sequence information can be transferred from a DNA helix to another DNA helix
Germ cell
a cell in germ line of organism, includes haploid gametes and their specified diploid precursor cells, contribute to formation of new generation of organisms
Histone chaperone
protein that binds free histones, releasing them once they have been incorporated into newly replicated chromatin
Holliday junction
x-shaped structure observed in DNA undergoing recombination, two DNA molecules are held together at site of crossing-over
Homologous recombination
genetic exchange between a pair of identical or very similar DNA sequences, DNA repair mechanism for double-strand breaks
Hybridization
process where two complementary nucleic acid strands form a base-paired duplex molecules
Lagging strand
one of two newly synthesized strands of DNA found at replication fork, is made in discontinuous lengths that are later joined covalently
Leading strand
one of two newly synthesized strands of DNA found at replication fork, is made in by continuous synthesis in 5’ to 3’ direction
Loss of heterozygosity
result of errant homologous recombination that uses homolog from the other parent instead of sister chromatid as template
Mutation rate
rate at which changes occur in DNA sequences
Nonhomologous end joining
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
Nucleotide excision repair
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
Origin recognition complex (ORC)
large protein complex that is bound to DNA at origins of replication in eukaryotic chromosomes throughout cell cycle
Rad51
eukaryotic protein that catalyzes synapsis of DNA strands during genetic recombination
RecA
protein in E. coli that catalyzes synapsis of DNA strands during genetic recombination
Replication fork
Y-shaped region of replication on DNA molecule at which two strands of DNA are being separated and daughter strands are being formed
Replication origin
location on a DNA molecule at which duplication of DNA begins
RNA primer
short stretch of RNA synthesized on DNA template, required by DNA polymerases to start their DNA synthesis
S phase
period of eukaryotic cell cycle in which DNA is synthesized
Single-strand DNA-binding (SSB) protein
protein that binds to single strands of opened-up DNA double helix, preventing helical structures from reforming while DNA is being replicated
Sliding clamp
protein complex that holds DNA polymerase on DNA during DNA replication
Somatic cell
any cell other than cells of the germ line
Strand exchange
reaction in which one of the duplex DNA molecule penetrates another duplex and searches it for homologous sequences through base-pairing
Telomere
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
Allele
one of several alternative forms of a gene
strand-directed mismatch repair
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
