High School Biology DNA Replication and Mutation Notes

1. DNA Replication

3. DNA and Chromosomes
oDNA is tightly packed
oA human cell contains more than 1 meter of DNA
oHow does it fit in the nucleus and form a chromosome?
oHistones are proteins that DNA twists around
oDNA and protein pack together to form a substance called
chromatin

4. DNA Replication
oMaking a copy of the genetic instructions of the cell
oBase pairing provides all the information needed to
replicate DNA
oEach strand is said to be “complementary”

5. Chromosome –
Tightly packed DNA
and proteins
DNA Polymerase – building
and proofreading enzyme
DNA Polymerase – building
and proofreading enzyme
Replication Fork
Y-shaped region where
original strand unwinds
Free nucleotides
Leading Strand
Lagging Strand
Helicase – untwists and separates the strand
Original DNA
Acts as a template
Original DNA
Acts as a template

6. Strand Differences
Leading Strand
◦Builds DNA toward the replication fork
Lagging Strand
◦Fills in with Okazaki fragments away from the replication fork
◦ Ligase with help glue together

7. DNA Mutation