DNA Replication

Cell Division and DNA Replication Cells divide -->Growth, Repair, Replacement Before cells divide they have to double cell structures, organelles and their genetic information (during which phase?)

DNA Replication Carried out by a series of enzymes (DNA polymerase and helicase) –The first enzyme “unzips” the two original strands of DNA –Another enzyme bonds free floating nucleotides together

DNA Replication The “original/old” molecule has two complementary strands of DNA. - base paired with its specific partner: A with T G with C

DNA Replication - Step 1 The first step in replication is the separation of the two strands by an enzyme. - “Unzips” in both directions --> hydrogen bonds broken

DNA Replication - Step 2 Free-floating nucleotides pair with bases on OLD strand - The old strand is a template that determines the order of the bases along a NEW strand. *NEW strand is IDENTICAL to the one from which it was “unzipped”

DNA Replication - Step 3 - Nucleotides are connected to form the sugar-phosphate backbones of the new strands. - Each “daughter” DNA molecule consists of one original strand and one new strand = Semi-Conservative Model of Replication

Replication Key Points –Replication COPIES the genetic information –PROTEINS (enzymes) carry out the process of replication –Replication is FAST and ACCURATE –Must occur BEFORE cell division (either Mitosis or Meiosis) –Can occur SIMULTANEOUSLY in many different places along the same strand of DNA

DNA Replication- if confusing…watch this simple video