Transcript DNA Replication - Mt. SAC Faculty Contact Directory

DNA Replication
Nucleotides
T.H. Morgan
Genes are located on chromosomes
Transformation
(Griffith 1928)
Avery, McCarty, MacLeod
(1944)
Genetic Material
Protein or DNA ????
"Studies on the chemical nature
of the substance inducing
transformation of pneumococcal
types"
Phages
Hershey & Chase (1952)
Linus Pauling (1948)
Alpha Helix Structure
Chargaff’s Rule
Adenine – Thymine
Guanine - Cytosine
Watson & Crick
Maurice Wilkins
X-ray diffraction
Rosalind Franklin
Nucleotides
X-ray Data
DNA Structure
Complimentary Strands
Semiconservative
Model
(Meselson & Stahl)
Semiconservative Model
(Meselson & Stahl)
Origin of Replication
DNA Nucleosides Triphosphates
Antiparallel
Enzymes
DNA Polymerase
Helicase
Single-strand binding protein
Topoisomerase
RNA primase
Ligase
RNA Primer
Uses RNA primase to
build RNA primer
Eventually replaced
with DNA by DNA
Polymerase
DNA
Replication
Leading and Lagging Strands
Leading Strand
Built in the 5’-3’
direction
Built toward the
replication fork
Built continuously
Uses one RNA Primer
Lagging Strand
Built in the 5’-3’
direction
Built away from the
replication fork
Built discontinuously
using Okazaki
fragments
Many RNA Primers
Overview
Proofreading
Mismatch Repair
Nucleotide Excision
Repair (nucleases)
End-replication Problem
Nucleotides can only
be added to 3’ end
Leaves gap on leading
strand
Each replication
causes DNA molecule
to get smaller
Telomeres
Telomeres
End of DNA strand
made up of
reoccurring DNA
sequence
Can be rebuilt with
telomerase (only in
germ-line cells)