DNA replication Flashcards
Each new DNA molecule has one OLD and one NEW strand of DNA.
This means DNA replication is…
semi-conservative replication
Are the new strands different from the first strand?
No, they are identical.
What are the parts to a nucleotide?
Phosphate, sugar, nitrogen base
What type of macromolecule is an enzyme?
protein
What is the function of DNA helicase?
Unzip or unwind the DNA
What is the function of DNA polymerase?
add new base pairs to the DNA
Which type of DNA polymerase adds bases during replication?
DNA Polymerase III
Which end of the DNA strand can we add new nucleotides to?
3’ end
DNA Primase does what?
Lays down a section of RNA to initiate the copying of DNA
DNA ligase…
connects the backbone (sugar-phosphate) of the DNA fragments together
okazaki fragments
Okazaki fragments are short sections of DNA formed at the time of discontinuous synthesis of the lagging strand during replication of DNA.
DNA easy to copy in a prokaryotic cell because…
a prokaryotic/bacteria cell has a single ring of DNA
There are multiple origins of DNA replication in eukaryotic cells because…
eukaryotic organisms have a lot of DNA and it would take too long to copy from end to end
process of dna replication
Unwinding and unzipping done by DNA helicase (draw something circular and label it). It produces a replication fork and the base pairs are exposed
An enzyme called DNA primase comes along and forms a primer (RNA). It acts as the base for DNA replicating
DNA polymerase III is to build the chain in the order of 5’ to 3’ and attaches to the primer and starts producing the chain of DNA by putting the nucleotides into the correct positions by complementary base pairing (A to T, G to C)
Leading strand has to be in the order of 5’ to 3’ while lagging strand is in the order of 3’ to 5’. Okazaki fragments are formed during the disconnected synthesis of DNA in the lagging strand
DNA polymerase I removes the primer and pol 3 adds DNA
DNA ligase fixes up any problems and fragments and fills the gap between the phosphate-sugar backbone and double checks the entire DNA double helix
DNA is semi-conservative (half of it is unchanged and is original while half of it is new and built)
Outline the role of DNA polymerase III in DNA replication.
a. binds to template strand adjacent to a primer/at the primer
b. adds nucleotides to template strand/to single stranded DNA
c. using complementary base pairing
d. links nucleotides with sugar-phosphate/phosphodiester bonds
e. adds nucleotides/builds new strand in 5’ → 3’ direction
f. lagging strand is built in short segments/Okazaki fragments/synthesis is discontinuous
Accept A to T and G to C instead of ‘complementary’
