DNA Replication

importance of DNA

prokaryotic and eukaryotic genomes made of this. “blueprint” for proteins. 

genome

made of many individual cells

dna copied

so each offspring gets instructions

dna and rna

are nucleic acids that govern cell life

nucleic acids

built from nucleotides

nucleotide parts

phosphate group, sugar (deoxyribose in DNA), and nitrogenous base

nitrogenous bases

adenine, guanine, cytosine, and thymine

purines

adenine and guanine

pyrimidines

cytosine, uracil, and thymine

double helix

long, double stranded DNA molecule

rungs of dna

consist of nitrogen bases

complementary nitrogen bases

A & T, G & C

side rails of dna

alternating pattern of sugar and phosphate molecules held together by phosphodiester bonds

in nucleotides, a base is attached to

1’ carbon of sugar

in nucleotides, a hydroxyl group (OH) is attached to

3’ carbon of a sugar

in nucleotides, a phosphate is attached to

5’ carbon of a sugar

directionality of DNA

5’ phosphate of first nucleotide bonds to 3’ hydroxyl group of next nucleotide

phosphodiester bonds

link nucleotides together to form sugar-phosphate “backbone” of DNA

antiparallel arrangement

one strand runs 5’ to 3’ and the other strand runs 3’ to 5’. allows complementary bases of DNA to bond

origin of replication

where enzymes collect and form a bubble w/ two replication forks

replisome

contains machinery necessary for replication. binds to origin of replication

seperating genome

DNA is supercoiled in nucleoid, must be separated to replicate

topoisomerases 

used to uncoil chromosome

helicase

unzips DNA by breaking hydrogen bonds between nitrogen bases to separate strands

single strand binding proteins

prevent two strands from rejoining each other to replicate

replication fork

two complimentary strands form

leading strand

replicated in direction fork opens

lagging strand

replicated in opposite direction as unwinding helix. replication proceeds away from replication fork

replication bubble

replication proceeds in both directions, forming this at origin of replication

energy to build molecule

provided by formation of phosphodiester bond

DNA polymerase requires

a 3’ OH to add bases

primase

synthesizes primer, makes primer out of RNA

primer

RNA sequence that begins DNA synthesize because it provides the 3’ OH to add bases

DNA polymerase III

binds to the 3’ OH of the primer. adds dNTPs 5’ to 3’

DNA polymerase I

removes RNA primer and replaces it w/ dNTPs

single stranded (SS) break

DNA polymerase I replacing primer leaves this in new DNA

DNA ligase

binds to either side of the single stranded break and glues it back together

leading strand replicates

continuously

primase attaches to lagging strand

when fork opens up enough

okaski fragments

small fragments of DNA on lagging strand caused by the DNA polymerase repeatedly hitting end of replication fork and waiting for it to open up

concatenated dna

two interlinked dna strand after replication is done due to circular nature of prokaryotic genome

topoisomerase IV after replication

causes double stranded nick and binds single DNA strands back together leaving two chromosomes