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Chapter 10 Section 3 DNA Replication. DNA Replication - the process by which DNA is copied in a cell before a cell divides . Enzymes involved…. 1. Helicase - an enzyme that separates DNA strands by breaking the hydrogen bonds between the bases. 1 .
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DNA Replication- theprocess by which DNA is copied in a cell before a cell divides
Enzymes involved… • 1. Helicase- an enzyme that separates DNA strands by breaking the hydrogen bonds between the bases 1
The action of the helicase enzyme creates a replication fork- the Y-shaped region that results when 2 strands of DNA separate • (See last slide)
2. DNA polymerase- enzyme responsible for adding nucleotides to exposed bases of each DNA strand *The nucleotides are floating around in the nucleus.
Semi-conservative replication • One strand of each of the new molecules is old and one strand is new.
Prokaryotic replication vs. Eukaryotic Replication • Prokaryotic replication involves 2 replication forks.
This makes the process of DNA replication in eukaryotes much faster than it would normally be at 53 days! • *Even at the pace of adding 50 nucleotides per second!
DNA replication is extremely accurate! • Any errors that occur are normally corrected with DNA polymerases.
Some errors are not repaired and sometimes damage can be done to DNA. • For example UV radiation can damage DNA along with various chemicals. • These damages can lead to cancer when mutations that affect genes that control how a cell divides can lead to an abnormal mass of cells called tumors. • Sometimes mutations are beneficial, too.