15. DNA replication Flashcards
DNA replication occurs during this phase of the cell cycle
S phase
the origin of replication of DNA is recognized by this group of proteins called
Origin Recognition Complex (ORC)
unwinds the double helix
helicase
maintain the separation of the parent strands
single-stranded DNA- binding proteins
relieve torsional strain the results from helicase-induced unwinding
Topoisomerase
Type I topoisomerase
Swivelase
Type II topoisomerase
Gyrase
Gyrase is inhibited by this antibiotic
Fluoroquinolones
synthesizes short segments of complementary RNA primers
Primase
elongates the DNA strand by adding new deoxyribonucleotides
DNA polymerase III
Direction of synthesis of DNA polymerase III proceeds in this direction
5’ to 3’ direction only
this DNA strand is synthesized continuously
leading strand
this DNA strand consist of Okazaki fragments
lagging strand
mismatched necleotides are removed in DNA replication using
3’–>5’ exonuclease
this enzyme fills the gap with deoxyribonucleotides
DNA polymerase I
seals the nick by catalyzing the formation of the last phosphodiester bond , requiring hydrolysis of ATP
DNA ligase
DNA lesion in Lynch syndrome (Hereditary nonpolyposis colon cancer)
mismatched strand
DNA lesion in
Xeroderma pigmentosum
pyrimidine dimers
DNA lesion in
MUTYH- associated polyposis
Base alterations
DNA lesion in
SCID , Severe combined Immune Deficiency
Double strand breaks
DNA lesion in
breast cancer susceptibility 1 and 2
doubt strand breaks
in eukaryotes RNA primers are removed by
RNAse H and FEN 1
DNA lesion caused by
errors that escaped proofreading
mismatched strand
DNA lesion caused by
exposure to UV light
pyrimidine dimers
DNA lesion caused by spontaneous or deaminating compounds
base alterations
DNA lesion caused by
ionizing radiation, free radicals, anti-tumor drugs
double strand breaks