Download Chemical Nature of the Gene

DNA: The Chemical Nature of
the Gene
Chapter 10
Chapter 10: Lecture Outline
Historical perspective
DNA structure
RNA structure
Early historical perspective
We enter the 20th century with an
understanding of the DNA building
block.
Some Experimental Data leading to
DNA as biological source of DNA
• Griffith’s
• Avery et al.
• Hershey and Chase
• Chargaff
• Wilkins and Franklin
• Watson and Crick
Streptococcus pneumonia
Rough Strain
Smooth Strain
Griffith’s Experiment: 1928
Conclusion:
A Transformation “factor” exists
1944: Avery;MacLeod;McMarty
• Discovered tranforming
principle as DNA
Oswald Avery
Avery, MacLeod & McCarty
IIIS virulent bacteria
Heat killed; homogenize and filter
Destroy either RNA; protein or DNA
Add samples to non-virulent bacteria
Only bacteria without IIIS DNA did not
transform
August 20, 2003
Martha Chase dies:
With Alfred D. Hershey, she established DNA as
the genetic material | By Milly Dawson
1908 — 1997
1930-2003
Hershey and Chase Experiment,
1952: Confirms DNA as genetic material
Support for nucleic acid transfer
Conclusion: DNA identified as
source of genetic information
At the same time amore detailed chemical
Structure of DNA was also ongoing…
1920-1958
Franklin and Wilkins 1947
1916-2004
Chargaff’s Rule 1948
1905-2002
1905-2002
Watson and Crick, 1953
inferred the DNA structure
Nobel Prize: 1962
1916-2004
1928-
1916-2004
Fraenkel-Conrat 1956:
RNA also carries genetic information
VIRAL RNA
Tobacco Mosaic Virus
The Structure of Genetic Material
The building blocks of DNA are
nucleotides.
RNA’s Sugar
DNA’s Sugar
Nitrogenous Bases
DNA nucleotides
Polarity and Anti-Parallel
Back to Franklin and Wilkins Data: Pairing of specific classes of
bases can account for diameter of DNA
6 sided ring
6 sided ring +
5 sided ring
Just right!
Most Common Secondary Structure (3D structure)
• B-DNA
• Alpha Helix
• Right Handed Turn
• 10 bases per 360º turn
A function of Major and Minor Grooves
DNA
Special structures
Modifications
’
Integration of DNA and RNA
Information Transfer
Central Dogma