Replication

continuity

DNA replication exists to ensure the ? of hereditary info

Synthesis

DNA replication occurs before cell division, specifically during the ? phase of the cell

Semiconservative

DNA is ? because it contains one original strand and one newly synthesized compliment (from replication)

5’ End

The end of DNA that has the phosphate terminus

3’ End

The end of DNA that has the hydroxyl terminus

Antiparallel

The feature of DNA where two strands run opposite to each other

• one is 5’-3’ while the other is 3’-5’

added, 3’

When new nucleotides are ?, it can only happen to the ? end

Leading Strand

strand of DNA that is synthesized continuously

• towards the fork

Lagging Strand

strand of DNA that is synthesized in fragments

• away from the fork

• it’s harder to work backwards so it must be done in fragments

  • this strand of DNA occurs because DNA polymerase can only add bases on the 3’ end, meaning it must wait for helicase to finish unzipping every time it adds a new set of fragments

directionality

? is based on the strand being made, not the template strand

DNA Polymerase

enzyme that synthesizes new strands by attaching to the 3’ end of the template strand and adds new bases from 5’ to 3’

• needs primase to create short RNA segments before this enzyme can work

Ligase

enzyme that joins DNA fragments on the lagging strand

Topoisomerase

Enzyme that relaxes the supercoil of DNA and helps form the replication fork

• comes before helicase

Helicase

enzyme that unwinds DNA by breaking hydrogen bonds

Okazaki Fragments

sections of copied DNA created on lagging strand

Primase

enzyme that initiates synthesis of DNA by creating a short RNA segment before polymerase