Lecture 26 - 27

DNA: THE GENETIC MATERIAL.

Table 12-1, p. 263

Fig. A, p. 86Acetabularia mediterranea (Mermaid’s wineglass)

Fig. 12-1, p. 261

Smooth, encapsulated, virulent

Rough, unencapsulated, avirulent

Fig. 12-2, p. 262

35

S Bacterial viruses grown in 35S to label

protein coat or 32P to label

DNA

32 P

Viruses infect bacteria

1

2

Fig. 12-2, p. 262

Agitate cells in blender

Agitate cells in blender

Separate by centrifugation

Separate by centrifugation

35

S

32 P

Bacteria in pellet contain 32P-labeled

DNA35S-labeled protein in

supernatant

3

4

5

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 helixUniform width of 2 nmBases 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

Fig. 12-13b, p. 274

340 nm

The End.