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Lecture 26 - 27
DNA: THE GENETIC MATERIAL.
Table 12-1, p. 263
Acetabularia mediterranea (Mermaid’s wineglass)
Fig. A, p. 86
Fig. 12-1, p. 261
Smooth, encapsulated,
virulent
Rough,
unencapsulated,
avirulent
35
S
1
32 P
Bacterial
viruses grown
in 35S to label
protein coat or
32P to label
DNA
2
Viruses infect
bacteria
Fig. 12-2, p. 262
3
Agitate cells in
blender
Agitate cells in
blender
4
Separate by
centrifugation
Separate by
centrifugation
35
S
5
32
P
Bacteria in pellet
contain 32P-labeled
DNA
35S-labeled
protein in
supernatant
Fig. 12-2, p. 262
Heinz Fraenkel-Conrat (1957)
Friedrich Miescher
(1844-1895))
Phoebius Levene
(1869-1940)
Erwin Chargaff (1905-2002)
Rosalind Franklin
The diagonal pattern of
spots stretching from 11 to 5
and from 1 to 7 o’clock
provides evidence for the
helical structure of DNA.
The elongated horizontal
patterns at the top and
bottom indicate that the
purine and pyrimidine bases
are stacked 0.34 nm apart
and are perpendicular to the
axis of the DNA molecule.
X-ray diffraction image of DNA
Rosalind Franklin (1952)
X-ray crystallography
Periodicity of 3.4 nm (= 10 nucleotides)
Double helix
Uniform width of 2 nm
Bases are flat and perpendicular to the
long axis of the molecule
Lecture 28 - 29
DNA REPLICATION.
Table 12-3, p. 270
DNA polymerase
Fig. 12-10, p. 271
Telomerase activity (1)
Telomerase activity (2)
Fig. 12-15, p. 276
340 nm
Fig. 12-13b, p. 274
The End.