DNA Replication

DNA Replication on the Chalkboard

DNA Replication in the Text at the Website

1. Close-up on replication
2. Initiation of replication is under close control
3. Strand Separation
4. Promoted by helicases, "DNA strand snow-plows which burn ATP and move along the DNA duplex.
5. Single-stranded binding proteins (helix-destabilizing proteins) which maintain single stranded nature until replication passes.
   
   (Figure adapted from Purves et al. Chapter 11)
6. Priming is required because no DNA replication enzymes can start a DNA strand de novo.
   
   (Figure adapted from Purves et al. Chapter 11)
7. Priming is accomplished by laying down a short strand of RNA, complementary to the DNA template by the enzyme "primase" which exists in a complex called a "primosome". Remember U is incorporated instead of T and the sugar is ribose not deoxyribose.
8. Leading strand synthesis proceeds after 1 priming event.
9. Lagging strand synthesis is done in "patches" called Okazaki fragments.
   
   (Figure adapted from Solomon et al.)
10. Nicks are sealed by a DNA ligase which joins adjacent 3'- OH and 5'- P in a reaction which utilizes the energy of ATP hydrolysis.
11. Let's look at a simple DNA polymerase (DNA Polymerase I from Thermus aquaticus) Requires Chime plugin and only works with Netscape.
12. Here's a couple of DNA polymerase images that don't rely on the Chime plugin.

Quicktime Movies of DNA Replication

A quick overview of DNA Replication (9.6 Mbytes) is found in this animation.
(Adapted from media provided with Purves et al.)

This page ©Copyright Peter B. Berget
All Rights Reserved