DNA REPLICATION 5 2 Notes DNA Replication Purpose

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DNA REPLICATION

DNA REPLICATION

5 -2 Notes: DNA Replication

5 -2 Notes: DNA Replication

Purpose of DNA Replication • Why does DNA replicate?

Purpose of DNA Replication • Why does DNA replicate?

DNA Replication • Making a copy of DNA (DNA DNA) • Location: Nucleus •

DNA Replication • Making a copy of DNA (DNA DNA) • Location: Nucleus • Enzymes Used: Helicase and DNA Polymerase

Steps of DNA Replication 1. Helicase unzips and unwinds the DNA strands by breaking

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 2. DNA Polymerases add complementary nucleotides to exposed strands

Steps of DNA Replication 3. Process continues until entire strand is copied • Result

Steps of DNA Replication 3. Process continues until entire strand is copied • Result is two identical strands of DNA

T A A C A G A A T T G T C T

T A A C A G A A T T G T C T 1. First the DNA must unzip: Enzymes split apart the base pairs and unwind the DNA.

T A A C A G A A T T G T C T

T A A C A G A A T T G T C T

T A A C A G A A T T G T C T

T A A C A G A A T T G T C T

T A A C T A T T A G A C T T

T A A C T A T T A G A C T T G T 2. Bases pair up: Free nucleotides in the cell find their complementary bases along the original strand.

T A A C A G A T A C T A T T

T A A C A G A T A C T A T T G T C T

T A A C A A T T G A C T T A

T A A C A A T T G A C T T A T C A T G T

T A A C A G A T C T C G T A

T A A C A G A T C T C G T A A A T T G

T A A C A G A T G T C T G T

T A A C A G A T G T C T G T T A A C A A T T G T

T A A C A G A T T G T C T

T A A C A G A T T G T C T

T A A C A C A G A A T T G T

T A A C A C A G A A T T G T G T C T The DNA is now duplicated:

End Result • Two identical molecules of DNA • They have one new and

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

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

Accuracy and Repair • Copies must be 100% accurate • Mutation= change in nucleotide at one location • Enzymes proofread and fix errors

Class work DNA Replication worksheet 1. Answer questions at the top 2. Use page

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)