The Double Helix

Question 1

What is Chargaffs rule

Answer 1

A=T and C=G

Question 2

What experimental procedure was conducted by Rosalind Franklin to identify the secondary structure of DNA

Answer 2

x-ray crystallography

Question 3

What was the first useful X-ray diffraction image of DNA called

Answer 3

photo 51

Question 4

What does photo 51 prove

Answer 4

DNA is helical

Question 5

Is the sugar backbone of DNA hydrophobic or hydrophilic

Answer 5

hydrophilic (hydrophobic portions face inward)

Question 6

The vertically stacked base pairs in a helix are _______A apart

Answer 6

3.4 A

Question 7

Each turn of the helix contains ~_____ base pairs

Answer 7

10 (3.4 A)

Question 8

How large is the diameter of the double helix

Answer 8

20 A (2nm)

Question 9

How many hydrogen bonds between C and G

Answer 9

3

Question 10

How many hydrogen bonds between A and T

Answer 10

2

Question 11

What is supercoiling

Answer 11

when a coil coils onto itself (coil of a coil)
- think of a phone cord

Question 12

Are the glycosidic bonds between base pairs linear?

Answer 12

no, at an angle
- causes major and minor grooves

Question 13

What forces stabilize the double helix

Answer 13

hydrophobic effect
H-bonding of base pairs