DNA Replication NotesDNA Replication Notes

DNA ReplicationDNA ReplicationReplication of DNA:Replication of DNA:DNA unwinds and DNA unwinds and each strand serves as each strand serves as a template for new a template for new DNA.DNA.This means you will This means you will have 2 copies of the have 2 copies of the same DNA after same DNA after replication.replication.

DNA ReplicationDNA ReplicationHelicaseHelicase: is the enzyme that unwinds (breaks : is the enzyme that unwinds (breaks bonds) and separates the two strands of DNA.bonds) and separates the two strands of DNA.Helicase breaks the hydrogen bonds that were Helicase breaks the hydrogen bonds that were hold the two nitrogen bases together.hold the two nitrogen bases together.

DNA ReplicationDNA ReplicationDNA polymeraseDNA polymerase: enzyme that adds nucleotides : enzyme that adds nucleotides to each strand of DNA.to each strand of DNA.Many polymerases attach at the same time.Many polymerases attach at the same time. On a fruit fly DNA replication starts at 6,000 different On a fruit fly DNA replication starts at 6,000 different

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DNA ReplicationDNA Replication

According to the base pairing rules, what According to the base pairing rules, what would the new stand of DNA be if the would the new stand of DNA be if the original strand was:original strand was:A – T – T – C – C- G A – T – T – C – C- G

New strand would be:New strand would be:T – A – A – G – G – C T – A – A – G – G – C

DNA ReplicationDNA ReplicationAccuracy and RepairAccuracy and RepairDNA is copied with a high degree of DNA is copied with a high degree of accuracy, there are enzymes that proof accuracy, there are enzymes that proof read DNA while its being replicated.read DNA while its being replicated.

DNA ReplicationDNA ReplicationMutationMutation: change in the nucleotide : change in the nucleotide sequence of DNA; it can have serious sequence of DNA; it can have serious effects on the organism.effects on the organism. Can be harmful or beneficialCan be harmful or beneficial

DNA ReplicationDNA Replication

Environmental factors Environmental factors can damage DNAcan damage DNA Ex. Ultraviolet radiation Ex. Ultraviolet radiation

from the sun, enzymes from the sun, enzymes in the cell work to repair in the cell work to repair the damaged DNA.the damaged DNA.

Without repair Without repair enzymes, mutations enzymes, mutations would occur more often would occur more often and cells would die and cells would die easier.easier.