Conformations of DNA

Question 0

What is contained in the B conformation and what is its purpose?

Answer 0

Sodium salt of DNA

Stabilizes the DNA

Question 1

The DNA structure of Watson and Crick represented the ______ of DNA

Answer 1

B Form

Question 2

When does the B conformation form?

Answer 2

Under conditions of relatively high humidity (92%)

Question 3

What is the common form of DNA? Why?

Answer 3

B Form

It is very close to the conformation of most DNA in cells

Question 4

How many base pairs are in the B form per helical turn?

Answer 4

10 per helical turn

Question 5

What is the pitch of B form DNA?

Answer 5

34Å

Question 6

Define pitch as it refers to DNA

Answer 6

1 turn of the helix

Question 7

In the B form, describe the position of the base pairs

Answer 7

Base pairs are perpendicular to the helical axis

Question 8

The ____________ of DNA changes conformations

Answer 8

Sodium salt

Question 9

When does DNA assume the A form?

Answer 9

When the humidity surrounding DNA is reduced to 75%

Question 10

In the A form, describe the position of the base pairs

Answer 10

The base pairs Are tilted about 20 degrees from horizontal

Question 11

I the A form, how many bass pairs are in a helical turn?

Answer 11

11 per helical turn

Question 12

In the A form, what is the pitch?

Answer 12

28Å

Question 13

What is an example that assumes the A form?

Answer 13

DNA-RNA hybrids

Question 14

What type of helix does A and B DNA form?

Answer 14

Right- handed

Question 15

What is the structure of Z-DNA?

Answer 15

dsDNA composed of alternating purines and pyrimidines that exists as a left handed helix

Question 16

What is the pitch of Z-DNA?

Answer 16

46Å

Question 17

How many base pairs are in a helical turn of Z-DNA?

Answer 17

12 base pairs

Question 18

In Z-DNA, describe the position of the base pairs

Answer 18

The base pairs have a 9 degree inclination from the helical axis

Question 19

Where is z-DNA found?

Answer 19

In small proportions in cells

Question 20

What is the function or purpose of Z-DNA?

Answer 20

It is not yet known

Question 21

How many forms of DNA are there?

Answer 21

Three

Question 22

Compare the pitch for the three forms of DNA.

Answer 22

A = 28Å
B = 34Å
Z = 46Å

Question 23

Give an example of a sequence of z-DNA

Answer 23

• GCGCGCGCGCGC-

- CGCGCGCGCGCG-

Question 24

Why was the z-DNA named such?

Answer 24

The backbone appeared to ‘zig-zag’