DNA Replication

DNA and ChromosomesoDNA is tightly packedoA 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

DNA ReplicationoMaking a copy of the genetic instructions of the cell

oBase pairing provides all the information needed to replicate DNAoEach strand is said to be “complementary”

Chromosome –Tightly packed DNA and proteins

DNA Polymerase – building and proofreading enzyme

DNA Polymerase – buildingand proofreading enzyme

Replication ForkY-shaped region where original strand unwinds

Free nucleotides

Leading Strand

Lagging Strand

Helicase – untwists and separates the strandOriginal DNAActs as a template

Original DNAActs as a template

Strand DifferencesLeading Strand◦ Builds DNA toward the replication fork

Lagging Strand◦ Fills in with Okazaki fragments away from the replication fork

◦ Ligase with help glue together

DNA Mutation