DNA REPLICATION

REVIEW Shape of DNA is Base Pair Rules Adenine pairs with Cytosine pairs with Double Helix Thymine Guanine

Why must DNA replicate? DNA is the physical carrier of inheritance. Species could not survive and individuals could not successfully reproduce

Cells will divide and make an exact copy of the cell. DNA has all the genetic information so it must be copied also.

REPLICATION Process of copying DNA

Process of Replication 1.Double helix unwinds. DNA helicase – enyzme that opens the double helix by breaking hydrogen bonds between the bases.

Replication Fork Area where the double helix separates Y-shaped

2. DNA polymerase – enzyme that moves along each DNA strand and adds nucleotides according to base pair rules.

Example G C A T

3. Process continues until all of the DNA is copied and DNA polymerase detaches. DNA will wind back.

RESULT = 2 Identical DNA strands

ERROR!!!!! DNA polymerase can backtrack and proofread the nucleotide pairing. It can be fixed.

Rate of Replication Bacteria – have circular DNA 2 replication forks at a single point and move away from each other.

Eukaryotic Cells – each chromosome is a single long strand of DNA. If you replicate from 1 end to the other it would take

33 DAYS!!!!

So, each strand is replicated in sections that are 100,000 nucleotides long This takes 8 hours. Replication Forks DNA strand