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15 Cards in this Set
- Front
- Back
replication bubble |
a long strand of A:T pairs that form a localized zone of denaturation -essential first step in replication of DNA |
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Prok: DNA Polymerase |
-synthesizes 5'-->3' -require a free 3'-hydroxyl group |
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lagging strand |
-strand that extends 3'-->5' -grows by the synthesis of Okazaki fragments and the subsequent covalent bonding of these short fragments |
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DNA Ligase |
-links Okazaki fragments -cataylzes the covalent closure of nicks in DNA by using energy from NAD or ATP |
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RNA Polymerase |
-cataylzes the synthesis of RNA molecules from DNA templates -initiates the synthesis of new RNA chains at specific sites on the DNA |
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each new DNA chain is initiated by a short.. |
RNA primer synthesized by DNA primase |
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DNA polymerase III |
catalyzes the semiconservative replication of the chromosome -catalyzes the addition of deoxyribonucleotides to RNA primers -terminates an Okazaki fragment when it bumps into the RNA primer of the preceding Okazaki fragment |
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DNA Polymerase I |
-excises and replaces RNA primers with DNA chains -has 2 exonuclease activities |
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DNA polymerase I exonuclease activity |
-5-->3 excises the RNA primer and replaces the RNA with a DNA chain -3-->5 exonuclease activity cleaves off nucleotides from the 3' termini of DNA strands |
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DNA helicase |
unwinds DNA using energy from ATP |
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SSB protein |
after DNA is unwound, it has to be kept in an extended single strand state, so this protein coats the strains to maintain this |
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DNA Topoisomerases |
the enzymes that provide the required axes of rotation during the replication of circular DNA molecules |
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Top 1 and Top 2 |
1: removes supercoils from DNA one at a time oriduce temporary single strand breaks or nicks in DNA 2: produce transient double strand breaks in DNA and remove and introduce negative supercoils two at a time |
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S phase |
dna replication occurs in S phase (g1, g, s, g2, mitosis) |
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eukaryotes: replication protein |
equivalent to ssb protein in prokaryotes, keeps unwound strands in extended state |