Chapter 15: DNA and the Gene: Synthesis and Repair [MIDTERM 2 MATERIAL]
University of Massachusetts Amherst
DNA and the Gene: Synthesis and Repair
The Chromosome Theory of Inheritance
"Chromosomes contain genes"
Watson and Crick
"DNA directionality and polarity"
3', 5' Ends
Complimentary Base Pairing
The Hershey - Chase Experiment
"DNA or Protein?"
Escherichia Coli Bacteria (E. Coli)
Capsid "Exterior Protein Coat"
1) Proteins contain Sulfur but not Phosphorous
2) DNA contain Phosphorous but not Sulfur
Results: Radioactive 35S was outside the cell in the capsid while radioactive 32 P was inside the
The Meselson-Stahl Experiment
"Semiconservative: Each newly made DNA comprises of one old and new strand"
Escherichia Coli Bacterium
15N - Heavier (template)
14N - Normal Isotope, lighter (replicated)
"separate molecules based on density"
15N band lower in centrifuge
DNA Synthesis - THE REPLISOME
Multiple Origins (Eukaryotes)
Single Origin (Prokaryotes)
DNA Helicase "break hydrogen bonds"
Single Strand Binding Proteins SSBP "prevent coiling" Topoisomerase "cuts DNA, allows it to unwinds, then rejoins it"
"After an RNA primer is in place, DNA polymerase moves along adding deoxyriboneucleotides to
the 3' end of that strand. The enzymes moves into the replication fork, which unzips ahead of it"
Deoxyribonucleoside Triphophates (dNTP)
High Potential Energy