Module 3 Summary Forms

Question 1

Helix Handedness

B-DNA

A-DNA

Z-DNA

Answer 1

B-DNA Right

A-DNA Right

Z-DNA Left

Question 2

Base pairs (bp) per helical turn

B-DNA

A-DNA

Z-DNA

Answer 2

B-DNA ~10

A-DNA ~11

Z-DNA ~12

Question 3

Vertical rise per bp (A)

B-DNA

A-DNA

Z-DNA

Answer 3

B-DNA 3.4

A-DNA 2.56

Z-DNA 3.7

Question 4

Rotation per bp
B-DNA

A-DNA

Z-DNA

Answer 4

B-DNA +36

A-DNA +33

Z-DNA -30

Question 5

Helical diamter (A)

B-DNA

A-DNA

Z-DNA

Answer 5

B-DNA 20

A-DNA 23

Z-DNA 18

Question 6

Major groove

B-DNA

A-DNA

Z-DNA

Answer 6

B-DNA Wide, deep

A-DNA Narrow, deep

Z-DNA Flat

Question 7

Minor groove

B-DNA

A-DNA

Z-DNA

Answer 7

B-DNA Narrow, deep

A-DNA Wide, shallow

Z-DNA Narrow, deep

Question 8

Extra details (3)
B-DNA

Answer 8

B-DNA
has a SMOOTH BACKBONE

highly VARIABLE and MALLEABLE

It can adopt MULTIPLE CONFORMATIONS in response to ENVIRONMENT which can affect PROTEIN RECOGNITION

Question 9

Extra details (2)
A-DNA

Answer 9

A-DNA
BIOLOGICAL RELEVANCE of A-DNA: underwind for REPLICATION FIDELITY

Has been observed under CONDITIONS of REDUCED WATER CONTENT

Question 10

Extra details (2)
Z-DNA

Answer 10

Z-DNA
Usually in locations NEAR the site of TRANSCRIPTION INITIATION

Zigzag backbone

Question 11

Is SEQUENCE SPECIFIC, COOPERATIVE, and REVERSIBLE.

This transition can occur under certain condiitons, such as changes in TEMPERATURE, PRESSURE, or SALT CONCENTRATION

Answer 11

The B-DNA to A-DNA (B -> A) transition

Question 12

is REVERSIBLE, similar to RNA POLYMERASE, which turns UNWOUND DNA into Z-DNA and converts it back to B-DNA after transcription

Answer 12

The B - > Z transition