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DNA Replication. Ms. Edmondson. Facts. DNA has to be copied before a cell can divide. DNA is copied in the S phase synthesis of interphase New cells will need identical DNA strands. More Facts…. Why?
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DNA Replication Ms. Edmondson
Facts • DNA has to be copied before a cell can divide. • DNA is copied in the S phase synthesis of interphase • New cells will need identical DNA strands
More Facts… • Why? • When cells replicate, each new cell needs it’s own copy of DNA to preserve the hereditary material. • Where? • Nucleus in Eukaryotes. • Cytosol in Prokaryotes • When? • S phase of cell cycle • What? • Many proteins: major is Helicase and DNA Polymerase • How?
Steps… • DNA Helicaseunwinds the DNA strand. • Other enzymes hold the strands apart creating a, replication fork open. • DNA Polymerasemoves along the separated strands and adds bases to the exposed strands using the base pairing rule. • The sugar phosphate backbone reforms and two identical strands of DNA are formed.
A closer look… • Bonds between the bases are broken and the strand unwinds.
A closer look… • The DNA strands separate to form a replication fork.
A closer look… • DNA polymerase adds the bases to the to the exposed strands using the base pairing rule.
A closer look... • Two identical strands are formed.
Semi-Conservative • Semi-conservative Replication- This means that each strand is composed of one old strand and one new strand.
Let’s see it in action… • DNA Replication in Action!