IB Topics3.4 & 7.2- DNA Replication Focus Question: How does DNA replicate? IB Topics: 3.4 DNA Replication 7.2 DNA Replication

DNA Replication

Direction of DNA Replication DNA replication occurs in a 5’ to 3’ direction!

Enzymes drive replication Helicase DNA polymerase III, RNA primase DNA polymerase I DNA ligase

Okazaki fragments In eukaryotes, replication is initiated at many points concurrently.

DNA Replication Semi-conservative-

Excision Repair

Replication Enzymes Which enzymes are important for DNA replication?

Helicase 1) unwinds the double helix 2) breaks apart the H-bonds between base pairs

RNA Primase Assembles and positions RNA primer

Deoxynucleoside triphosphate not an enzyme, but an important molecule Contains the base, sugar and three phosphates The precursor to a nucleotide.

DNA Polymerase III Facilitates the joining of deoxynucleoside triphosphate to the template strand. Condensation reaction, two phosphates are removed, rest stays on strand. Water forms Adds nucleotides in the 5’ to 3’ direction

DNA Polymerase I Removes RNA primer and replaces with DNA

DNA Ligase Attaches DNA segments of Okasaki fragments.

DNA Replication Initiated at many points Animation