8.3 DNA Replication VOCABULARY Replication The process by which DNA is copied during the cell cycle....

8.3 DNA Replication

VOCABULARYReplicationThe process by which DNA is copied during the cell cycle.

DNA PolymeraseAn enzyme that forms bonds between nucleotides during replication.

Semi-ConservativeEach DNA molecule contains an original strand of DNA and one new strand of DNA.

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

MAIN IDEA

1.

2.

3.

8.3 DNA Replication

Replication copies the genetic information.

• A single strand of DNA serves as a template or a pattern for a new strand.

• The rules of base pairing directreplication. A=T C=G

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

• Each body cell gets acomplete set ofidentical DNA.

– EX: Your brain cells know how to make skin cells, but they don’t use this information.

8.3 DNA Replication

Proteins carry out the process of replication.

• DNA serves only as a template (pattern). • Enzymes and other proteins do the actual work of

replication.– Enzymes unzip the double helix

In both directions.

– Free-floating nucleotides form hydrogen bonds with the template strand.

nucleotide

The DNA molecule unzips in both

directions.

8.3 DNA Replication

– Polymerase enzymes form covalent bonds between nucleotides in the new strand.

– DNA polymerase enzymes bond the nucleotides together to form the double helix.

DNA polymerase

new strand nucleotide

8.3 DNA Replication

• DNA replication is semiconservative.

original strand new strand

Two molecules of DNA

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

8.3 DNA Replication

There are many origins of replication in eukaryotic chromosomes.

• DNA replication starts at many points in eukaryotic chromosomes (it is faster and more efficient this way).

Replication is fast and accurate.

• DNA polymerases can find and correct errors.• If a part of the DNA is incorrect only that part is

repaired.