6.4 DNA Replication

Matthew Meselon and Franklin Stahl

came up with semi conservative replication

double stranded

dna is ?

semi-conservative replication

complementary strand is made from each parent strand

replication

Strands are unwound from replication origins, forms a replication fork

true

each new one strand has one old strand and one new strand, true or false?

topoisomerase

cuts and rejoins strand to keep them from tangling

DNA helicase

strands are unwound by this enzyme

single-strand binding proteins

joins to unwound strands to prevent them from rejoining

annealing

the rejoining of unwound strands

replication bubbles

formed because many replications are going on, meet & merge

replication

adding new parts to the separated strands

polymerases

build strands in 5' -> 3' direction

nucleoside triphosphates

nucleotides are added as

hydrolysis

________ of extra phosphates provides energy for synthesis (from ATP)

phosphodiesther

the extra phosphates make up the __________________ bonds on the sides

DNA synthesis

the released energy drives ?

RNA primase

builds small complementary RNA primers at the replication fork on its own

RNA primers

short pieces made by RNA primase

DNA polymerase III

synthesizes complementary strands in opposite directions (5’ → 3’), can only add to previously existing nucleotides

DNA polymerase III

first DNA polymerase used, last one discovered

Leading

strand is elongated toward the fork; efficient, 5'

Lagging

is elongated away from the fork, requires multiple RNA primers: constantly being synthesized backwards (3’)

Okazaki fragments

lagging strands result in segments of RNA primers & DNA called

DNA polymerase I

replaces RNA primers with DNA - purifies

DNA ligase

joins Okazaki fragments into one continuous strand

repair

Mismatched base pairs don’t bond properly and distort shape of the DNA molecule, which phase is this fixed in?

DNA polymerase II

removes portion of the stand with mismatch and fills in the gap.