dna replication Flashcards
what stage in the cell cycle does dna replication take place
Interphase
s phase
GYRASE- this is the first enzyme used in dna replication. What does it do
Gyrase
Unwind/Untwists the double helix
DNA HELICASE- this is the second enzyme, what does it do
unzips
breaks the hydrogen bonds between base pairs to form 2 strands.
both of these 2 strands act as a template
resulting in two separate strands
what happens after dna is unzipped by dna helicase
free nucleotides in the nucleoplasm are attracted to exposed bases via complementary base pairing
DNA polymerase- what does it do
DNA Polymerase
catalyses the addition of nucleotides in a 5’3’ direction by condensation reaction to form phosphodiester bonds
. hydrogen bonds are also formed between complimentary base pairs.
what reaction joins nucleotides together and what bond is made
condensation reaction which removes a water molecule and forms a phosphodiester bond
why is it called semi-conservative replication
because one strand is conserved by the original dna molecule, and the other strand is newly created
why are the free roaming nucleotides in the nucleoplasm called “Activated nucleotides”
Because they usually contain extra phosphates
activated nucleotides are binded to the template nucleotides by phosphodiester bonds.
How are the extra phosphates removed
hydrolysis
release extra phosphates supplies energy to make phosphodiester bonds
what is the product of semi conservative replication
two identical dna molecules, which are identical to the parent molecule
consist of an old and new strand
how do prokaryote dna semi conservatively replicate
a bubble forms around the loop of dna
unzips and unwinds
complimentary bases join to exposed nucleotides
to replicate whole loop
what is the estimation of mutations during semi conservative replicaton
1 in 10(8) base pairs
8 meant to be small 8
what is a common mutation
wrong base pair inserted
what is an effect of mutation during dna replication
changed genetic code
how are mutation rates decreased
there are enzymes which can proofread and edit incorrections
