DNA Replication DNA is antiparallel The double helix

DNA Replication

DNA is antiparallel The double helix of DNA is antiparallel, meaning the two sugar-phosphate backbones are oriented in opposite directions.

How does DNA replication work? 1. ) Enzymes unzip the double helix in 2 directions nucleotide The DNA molecule unzips in both directions. Point of separation = Replication fork __________ What enzyme causes helix to separate? Helicase __________

2. Nucleotides pair with exposed bases on template -bases join together by hydrogen-bonds -sugar-phosphates join together by covalent bonds 3. DNA polymerase bonds new nucleotides together. -moves along chain, assembles new chains, corrects errors new strand nucleotide DNA polymerase

4. 2 new molecules of DNA are made New strand is complimentary to the original strand Two molecules of DNA If old strand is: ATTCCGT New strand is: TAAGGCA new strand

Replication is fast and accurate. • DNA replication starts at many points in eukaryotic chromosomes. There are many origins of replication in eukaryotic chromosomes. DNA polymerases can find and correct errors.

Which of the following DNA sequences is complementary to the base sequence ACCGTAT? A. B. C. D. GTTACGC UCCGTAT TGGCATA CAATGCG

What are the main functions of DNA polymerase? A. Breaks hydrogen bonds and exposes bases B. Holds DNA strands apart and attracts bases C. Zips and unzips the double-stranded DNA D. Binds nucleotides and corrects base pair errors