Biology 325: Advanced Genetics
Lecture I
Outline: I. Introduction
II. Early Studies of DNA
III. Molecular Structure of DNA
IV. Genetic Implications of DNA Structure
V. Special Structures in RNA and DNA
VI. DNA Methylation
VII. RNA as Genetic Material
I. Introduction: The Story of the Ice Man
A. Discovery
B. Questions
C. DNA Evidence
II. Early Studies of DNA
A. Fredrich Miescher (1869)
B. Albrecht Kessel
C. Pheobus Aaron Levene
D. Erwin Chargaff (1948)
III. Molecular Structure of DNA
A. Rosalind Franklin and Maurice Wilkins
B. James D. Watson and Francis Crick (1953)
C. The Double Helix
1. Components
2. Nucleosides
3. Nucleotide
4. Polynucleotide Strands
5. Double-stranded DNA
a. B-DNA
b. A-DNA
c. Z-DNA
|
Characteristic |
B-DNA |
A-DNA |
Z-DNA |
|
Conditions required to produce structure |
92% H20 |
75% H20 |
Alternating purine-pyrmidines |
|
Helix Direction |
Right-handed |
Right-handed |
Left-handed |
|
Average base pairs per turn |
10 |
11 |
12 |
|
Rotation per base pair |
36¡ |
32.7¡ |
-30¡ |
|
Distance between bases |
0.34nm |
0.26nm |
0.37nm |
|
Diameter of helix |
1.9nm |
2.3nm |
1.8nm |
|
Overall shape |
Long and narrow |
Short and wide |
Elongated and narrow |
IV. Genetic Implications of DNA Structure
A. Central Dogma of Genetics
V. Special Structures in RNA and DNA
A. Base pairing within single stranded polynucleotide strands
B. Hairpins, Stems, and Cruciforms
VI. DNA Methylation
A. DNA modification
B. Function of Methylation
VII. RNA as Genetic Material
A. Fraenkal-Conrad and Singer (1956)
B. Central Dogma in Retroviruses