8.3 DNA Replication

KEY CONCEPT DNA replication produces copies the genetic information of a cell.

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8.3 DNA Replication

Replication copies the genetic information.

• The rules of base pairing directreplication.

• DNA is replicated during theS (synthesis) stage of thecell cycle.

• Each body cell gets acomplete set ofidentical DNA.

8.3 DNA Replication

• In your packet

8.3 DNA Replication

Proteins carry out the process of replication. Identify the Structures:

1. Original DNA serves as template for assembling new.

2. Free-floating nucleotidesnucleotides form hydrogen bonds with the template strand.

3.3. EnzymesEnzymes and other proteins do the actual work of replication.– DNA Helicase Enzymes unzip the double helix.– DNA Polymerase Enzymes pull in nucleotides and

bond the sugar/phosphate backbone.

nucleotide

The DNA molecule unzips in both directions.

8.3 DNA Replication

4. Bonds!DNA polymerase enzyme helps hydrogen-bond the nucleotides.

Polymerase forms covalent bonds between backbonecovalent bonds between backbone sugars & phosphates in the new strand.

DNA polymerase

new strand nucleotide

8.3 DNA Replication

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8.3 DNA Replication

There are many origins of replication in eukaryotic chromosomes.

• DNA replication starts at many points in eukaryotic chromosomes.

Replication is fast and accurate.

• DNA polymerases can find and correct errors.

8.3 DNA Replication

DNA replication is a semi-conservative process.

• 1. Replication forks are formed in many places along eukaryotic DNA. This speeds up the process. Enzyme DNA Helicase opens the hydrogen bonds in both directions.

• 2. Enzyme DNA Polymerase pulls in free nucleotides to assemble the new strand.

• 3. Polymerases travel in opposite directions, bonding the nucleotides and backbones of the new strands.

8.3 DNA Replication

• DNA replication is semiconservative: One old, one new...

original strand new strand

Two molecules of DNA

• 4. Two new molecules of DNA are formed, each with an original strand and a newly formed strand.

8.3 DNA Replication

Replication copies the genetic information.

• Replication assures that every cell has a complete set of identical genetic information. Recall that your human eukaryotic DNA is divided into 46 chromosomes that are replicated during the Synthesis phase of the cell cycle. So your DNA is copied once per cell cycle, and each cell in your body has a complete set of DNA.

8.3 DNA Replication

Complete as HW