Zusammenfassung der Ressource
Chapter 14- BIOL 151
- Nature of
Genetic
Material
- 3 Major Experiments
- Griffith-1928:
Working with S and R
type pneumonia
causing bacteria
- Avery, MacLeod,
McCarty-1944: Expanded
Griffith's experiment,
removed other material.
showed that DNA transfer
caused changes
- Hershey & Chase-
1952: Experiments with
bacteriophages and
tagging with isotopes
- DNA Structure
- 3 Main Parts
- Phosphate Group
(attached to 5' end)
- 5-Carbon Sugar
- Nitrogenous Base
- Purines
- Guanine
- Adenine
- Pyramidines
- Thymine
- Uracil in RNA
- Cytosine
- Watson, Crick, Franklin
responsible for
discovering
Helix/Double-Helix
structure.
- DNA Replication
- Semiconservative Method:
Each daughter strand
contains one new copied
strand and one strand from
parent.
- Proved with
Messelson-Stahl
Experiment
- New strand built from 5' to 3' end
(reads parent strand 3' to 5')
- Begins at "replicon". Several
A-T bonds which are weaker
- "origin of replication"
- DNA gyrase prevents supercoiling
- a topoisomerase
- helicase separates the
double-helix into two
strands
- SSB proteins bind to single strand
to prevent reaction wit
surroundings
- DNA Primase creates
primer for attachment of
DNA Polymerase
- DNA Primase is an RNA
polymerase because it
makes RNA
- Lagging Strand
- Requires several
primers and
is written in
fragments
- Ozakai Fragments
- Stitched together with DNA ligase
- "Semidiscontinuous"
- Leading Strand
- 3 Types of DNA Polymerase
- Pol III does most
of the replication
- Beta-clamps keep Pol II attached to strand
- Pol I removes RNA
Primers and writes
in DNA
- Pol I repairs
- Full organelle is the "Replisome
- These two together are
called the "primosome"