DNA replication Flashcards
Where does DNA replication happen in the cell cycle?
S phase
Why does DNA replicate before cell division?
to have the same number of chromosomes in identical daughter cells
DNA replication step one
DNA helicase unwinds the original strand of DNA (enzyme)
-separates double helix
-replication fork
DNA replication step two
DNA polymerase builds the new polymer and new strands of DNA
-bases are according to which bases pair together
-elongation
DNA replication step three
leading and lagging strands are made
-every new strand grows from 5’ to 3’
-DNA ligase joins okazaki fragments together
DNA replication step four
two identical pieces of DNA (daughter strands)
leading strand
made continuously in the direction of the DNA polymerase
-5’ to 3’
lagging strand
made of okazaki fragments in the opposite direction of the DNA polymerase
semiconservative replication
uses half original DNA strand and half new to create the replicated DNA
antiparallel
DNA strands facing opposite ways
deoxyribose
sugar in DNA
phosphate
provides structure for DNA
nitrogenous bases
adenine, thymine, guanine, cytosine
purines
pair with pyrimidines
-adenine and guanine
pyrimidines
pair with purines
-thymine and cytosine
