BCH4024 - McKenna Lecture 48

BCH4024 McKenna - Central Dogma of Biology I-DNA can replicate Semi-conservative Ordered and sequential Uses activated substrates Very Accurate

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
1 “Central Dogma” of Biology I-DNA can replicate II-DNA can be transcribed into RNA III-mRNA can be translated into protein sequences Proteins determine (3D) our phenotype DNA RNA PROTEIN RNA Replicase DNA POL RNA POL Reverse Transcriptase Semi-conservative Ordered and sequential Uses activated substrates Very Accurate Numerous enzymes Template Driven A. DNA: DOUBLE TEMPLATE MOLECULE 1. Strands separate, each becoming template for assembly of a complementary strand RESULT: TWO IDENTICAL MOLECULES FROM ONE: 2. Replication is “semi-conservative Meselson-Stahl experiment confirmed basic hypothesis. Parental strands are conserved during subsequent rounds of replication. DNA REPLICATION Parental Duplex Intermediate in semiconservative replication Two daughter Duplexes Each strand is a template for a new Strand P P P P PP N N N N -Use of density gradients
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 The Meselson-Stahl Experiment 3. Base pairing rules completely dictate the sequence of the newly synthesized strand ( Watson-Crick ) Some Features of Replication Leading Lagging strand strand “okazaki fragments” continuous discontinuous synthesis synthesis Single stranded DNA template 5’ 3’ DNA RNA RNA primer Attached by primase (part of primosome) Newly synthesized strand. RNA primer is removed and gap is filled by DNA pol 1 DNA ligase joins bases DNA REPLICATION DNA Pol 1 DNA POL III RNA Polymerase Primer DNA Ligase
Background image of page 2
3 B. ACTIVITIES AT THE REPLICATION FORK Holoenzyme -10 P (POL III) Initiation Elongation Termination 1000 NT per sec All at the same time C. The Enzymes of E.coli DNA Replication Enzyme Role Topoisomerase Initiates DNA coil and supercoil unwinding by introducing nicks. (E.coli - DNA gyrase) Helicase Unwinds the double strand once nicked (ATP). Primase Synthesizes RNA primers and attaches it to unwound ssDNA strand. SSB Stabilizes ssDNA regions DNA POL III Synthesizes DNA (holoenzyme- 10 proteins) DNA POL I Removes primer and fills gaps DNA Ligase Joins the ends of DNA (3’OH and 5’ P) Provides 3’ OH Stimulates primase to make primers Unwinds, allows rotation and reseals Prevents degradation Work horse of replication, uses dNTPs - activated
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 D. Mechanics and Enzymes of Replication - Prokaryotic 1. Initiation a. Starts from specific origin b. DNA synthesis may be uni-or bi directional Origin = Initiation site Replication Forks Bi-drectional Uni-directional ds DNA Unwinding Most Common NT sequence that binds to Protein sequence – init. seq.
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/15/2010 for the course BCH 4024 taught by Professor Allison during the Spring '08 term at University of Florida.

Page1 / 14

BCH4024 McKenna - Central Dogma of Biology I-DNA can replicate Semi-conservative Ordered and sequential Uses activated substrates Very Accurate

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online