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21 Cards in this Set
- Front
- Back
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what functions does DNA polymerase do
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-maintains accuracy
-creates phosphodiester bond -copies template |
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requirements of DNA enzymatic synthesis:
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-4 activated precursors (dNTP's ACGT)
-Template strand -Short primer -Mg2+ |
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in the replication reaction mechanism which phosphate residue does the 3' hydroxyl attack
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ALPHA
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how is back reaction eliminated in replication
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H2O hydrolyzes PPi to 2 Pi
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Which direction does DNA polymerase move along the DNA template, and which direction is the new DNA molecule synthesized?
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Moves along template 3'-5'
Synthesizes in 5'-3' direction |
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Kornberg enzyme is aka
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DNA Polymerase I
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What are the three activities of DNA polymerase I
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DNA Polymerase
3' exonuclease 5' exonuclease |
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What is the function of 3' exonuclease in DNA Polymerase I
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to remove unpaired bases added to the 3' (hydroxyl) end of growing chain.
PROOFREADS - excises incorrect base pairings. |
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how is the lagging strand synthesized in DNA replication
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in okazaki fragments
short 3'-5' pieces |
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what enzyme synthesizes primers for DNA replication
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primase
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What enzyme elongates primers
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polymerase 3
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what kind of polymerase is PRimase
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an RNA polymerase
actually synthesizes short RNA's as primers. |
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Function of DNA polymerase 1 in dna replication:
How does it do its function? |
to remove RNA primers from the molecule.
Binds to 3' hydroxyl of okazaki fragments; sythesizes DNA while its 5' exonuclease hydrolyzes the RNA primer one nucleotide at a time. UNTIL 1 NICK is left. |
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what seals the last little nick in DNA during replication
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DNA ligase
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what supplies energy for DNA LIGASE to seal the last nick
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ATP or NAD hydrolysis
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funciton of GYRASE in transcription:
-what does it require |
introduces NEGATIVE supercoils downstream of replication site to counteract gyrating from twisting as DNA unwinds.
-Requires one ATP per supercoil |
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What does Helicase do and how?
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-Binds to lagging strand at fork to seperate the DNA double helix so two new strands can be synthesized.
Hydrolizes ATP for energy as leading strand advances. |
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WHAT DO SSB PROTEINS DO
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bind to lagging strand in wake of helicase
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How many subunits on DNA Polyerase 3?
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17, arranged in four subassemblies.
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the names of the four subassemblies on DNA polymerase 3:
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1. core polymerase
2. beta clamp 3. clamp loader 4. tau dimer |
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funciton of B-clamp
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binds to the core polymerase (site of enzyme activity) and holds it onto DNA template strand.
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