DNA ReplicationLS: I will be able to explain the process of DNA replication.
The Basics:1) A single strand of DNA
serves as a template for a new strand
2) DNA is replicated during S phase of the cell cycle
3) Each body cell gest a complete set of identical DNA
Replication = Copying
https://www.youtube.com/watch?v=FBmO_rmXxIw
Replication is fast and accurate
DNA serves only as a template
Enzymes and other proteins do the actual work of replication
DNA replication starts at many points in eukaryotic chromosomes
Enzymes Involved:1) RNA primase2) DNA helicase3) DNA gyrase
(mainly bacteria)4) DNA polymerase
I5) DNA polymerase
III6) DNA ligase
The process of replication:
1. DNA strands are unzipped at the points of origin by DNA helicase (site is known as the replication fork)
1. In bacteria, DNA gyrase is added to reduce the tension in the coiling of the DNA strands
2. RNA primase is added1. Identifies where the new
nucleotides need to be added
2. Both strands are used as templates, but constructed in opposite directions
What are the steps of replication?
Opposite directions = antiparallel
3. DNA polymerase III adds and binds new nucleotides to the growing DNA chain4. The DNA strands are checked for accuracy by DNA p0lymerase I5. The gaps are then corrected by DNA ligase
What happens
next?
DNA Replication follows the Semi-Conservative model
Which means:
Each strand of DNA will act as a template for the synthesis (“making of”) of a new
DNA molecule, following the base pairing rule
THEREBYCREATING 2 NEW DNA MOLECULES
THAT EACH HAS ONE OF THE ORIGINAL STRANDS AND ONE NEW STRAND
Semi-Conserva-a-what?
1. The enzyme ____________ unzips the double helix.2. RNA ______________ identifies where replication begins3. DNA _________________ binds free floating nucleotides to the template strand.4. DNA _________________ forms bonds between the two strands.5. DNA _________________ proofreads the new strands, and makes any corrections.6. DNA ____________ fills in any gaps on the developing DNA strand.
Let’s RECAP- The steps of replication: