DNA Replication
5-2 Notes: DNA Replication
Purpose of DNA Replication Why does DNA replicate?
DNA Replication Making a copy of DNA (DNADNA) Location: Nucleus Enzymes Used: Helicase and DNA Polymerase
Steps of DNA Replication 1. Helicase unzips and unwinds the DNA strands by breaking the hydrogen bonds
Steps of DNA Replication 2. DNA Polymerases add complementary nucleotides to exposed strands
Steps of DNA Replication 3. Process continues until entire strand is copied Result is two identical strands of DNA
A T C G A T G C 1. First the DNA must unzip: Enzymes split apart the base pairs and unwind the DNA.
A T C G A T G C
A T C G A T G C
A T C G T T A T G C 2. Bases pair up: Free nucleotides in the cell find their complementary bases along the original strand.
A T C G T C A T A T G C
A T C G C T T A T A A T G C
A T C G T C T C G T A A A T G C
A T C G G G T T T C T G T T A A C A C A A T G C
A T C G G G T T T T C T A A T A A C A C A G A T G C
The DNA is now duplicated: G A G G T T T T C T T A A C A C A G A A T G C The DNA is now duplicated:
End Result Two identical molecules of DNA They have one new and one old strand
Mechanism of DNA Replication DNA replication is said to be semiconservative since each new DNA molecule made has one old and one new strand.
Accuracy and Repair Copies must be 100% accurate Mutation= change in nucleotide at one location Enzymes proofread and fix errors
Homework Class work DNA Replication worksheet 1. Answer questions at the top 2. Use page 201 to create a labeled drawing of DNA Replication with descriptions of each step Homework Page 2 of DNA Book (due Monday) PQRST (due tomorrow)