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: