DNA ReplicationCopying the genetic code

Copying the genetic codeDNA Replication

Unpack the Chromosomes

Unzip the DNA

Base pairing at the replication fork

Leading strand vs Lagging strand

Making Copies

Making Copies

copycopied during cell division

Sister Chromatids(identical copies)

Accessing the DNAin

activ

e D

NA

(dea

ctiva

ted

or m

itotic

)

DNA in use

Visualization of DNA Packing

For this video, visit:http://www.hhmi.org/biointeractive/dna/DNAi_packaging_vo2.html

Accessing the DNA

Accessing the DNA

DNA Structure

Complementary Base Pairing

Identical Parent and Daughter Strands

Replication Bubbles

helicase

5’

3’

3’

5’

Replication Bubbles

5’

3’

3’

5’

Replication Bubbles

5’

3’

3’

5’

Replication Bubbles

copies

Replication Fork

Replication Fork

5’

3’

3’

5’

Replication Bubbles

Releasing the Tension

Releasing the Tension Topoisomerase (gyrase) cleaves and uncoils DNA ahead of helicase Single-stranded DNA binding proteins (SSB) prevent DNA from

coiling back up

DNA Replication

Primase

RNA primer

DNA Polymerase III

5’

3’

3’

5’

DNA Replication

The leading strands grow toward the replication fork PROBLEM: DNA polymerase III only works in the

5’-3’ direction.

Leading Strands5’

3’

3’

5’

DNA Replication

5’

3’

3’

5’

DNA Replication

Lagging Strands

The lagging strands grow away from the replication fork

5’

3’

3’

5’

DNA Replication

5’

3’

3’

5’

DNA Polymerase IDNA Ligase

DNA Replication

5’

3’

3’

5’

DNA Replicationcontinuous & discontinuous

Okazaki Fragments

5’

3’

3’

5’

DNA Polymerase moves in a 5’ - 3’ direction

5’-3’ chain synthesized continuously

3’-5’ chain synthesized discontinuously

Results in a series of Okazaki fragments

Later sealed up by DNA ligase

The Whole Process in 3D

For this video, visit: http://www.hhmi.org/biointeractive/dna

/DNAi_replication_schematic.html

The Whole Process in 3D

For this video, visit:http://www.hhmi.org/biointeractive/dna/DNAi_replication_vo2.html

Animations

DNA Replication: http://www.youtube.com/watch?v=4jtmOZaIvS0

McGraw-Hill: DNA Replication & Meselson-Stahl: http://highered.mcgraw-hill.com/sites/0072437316/st

udent_view0/chapter14/animations.html#

DNA Song: http://www.youtube.com/watch?v=dIZpb93NYlw

Credits

Molecule drawing created using ChemSketch.

Some from the Pearson or Nelson Biology 12 textbook.

Some images from Wikimedia Commons

Some from unknown sources.