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21 Cards in this Set

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what functions does DNA polymerase do
-maintains accuracy
-creates phosphodiester bond
-copies template
requirements of DNA enzymatic synthesis:
-4 activated precursors (dNTP's ACGT)

-Template strand
-Short primer
-Mg2+
in the replication reaction mechanism which phosphate residue does the 3' hydroxyl attack
ALPHA
how is back reaction eliminated in replication
H2O hydrolyzes PPi to 2 Pi
Which direction does DNA polymerase move along the DNA template, and which direction is the new DNA molecule synthesized?
Moves along template 3'-5'

Synthesizes in 5'-3' direction
Kornberg enzyme is aka
DNA Polymerase I
What are the three activities of DNA polymerase I
DNA Polymerase
3' exonuclease

5' exonuclease
What is the function of 3' exonuclease in DNA Polymerase I
to remove unpaired bases added to the 3' (hydroxyl) end of growing chain.

PROOFREADS - excises incorrect base pairings.
how is the lagging strand synthesized in DNA replication
in okazaki fragments
short 3'-5' pieces
what enzyme synthesizes primers for DNA replication
primase
What enzyme elongates primers
polymerase 3
what kind of polymerase is PRimase
an RNA polymerase

actually synthesizes short RNA's as primers.
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.
what seals the last little nick in DNA during replication
DNA ligase
what supplies energy for DNA LIGASE to seal the last nick
ATP or NAD hydrolysis
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
What does Helicase do and how?
-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.
WHAT DO SSB PROTEINS DO
bind to lagging strand in wake of helicase
How many subunits on DNA Polyerase 3?
17, arranged in four subassemblies.
the names of the four subassemblies on DNA polymerase 3:
1. core polymerase
2. beta clamp
3. clamp loader
4. tau dimer
funciton of B-clamp
binds to the core polymerase (site of enzyme activity) and holds it onto DNA template strand.