Chapter 8: DNA/RNA Characteristics

Question 1

Describe the Z Form of DNA

Answer 1

Z Form: Left Handed 18 A diameter (skinny). Alternating C, G Short Tracks in Prokaryotes & Eukaryotes. Its bases seem to zigzag.

Question 2

Describe the B Form of DNA

Answer 2

B Form: This is the most common form of DNA. It’s Right handed. 20 A diamater.

Question 3

Describe the A form of DNA

Answer 3

A form: Right handed DNA. 26 A Diameter (fat). Found in Non-aqueous Solution or salty solution. It’s the most crystalline form.

Question 4

What is a Palindrome?

Answer 4

DNA tracks in which complimentary strands have opposite sequences in the same spatial direction:

Question 5

What does the Phosphodiester Bond form?

Answer 5

The backbone of DNA

Question 6

How does the the Phosphodiester Bond form between two different nucelotides?

Answer 6

It forms a link between the 3’ OH group of one Sugar and the 5’ __ group of another Sugar:

Question 7

How many bases pair up between Adenine and Thymine and how long is the bond?

Answer 7

How long is the bond between Adenine & Thymine? It’s a longer bond because there are only 2 base pairs. The total distance is 11.1 Angstroms. A bit longer than the Guanine-Cytosine bond.

Question 8

How many bases pair up between Guanine and Cytosine?

Answer 8

3

It’s a shorter bond because there are 3 base pairs. Total distance is 10.8 Angstroms.

Question 9

What’s the size of the Minor Groove and Major Groove, and the Width of DNA?

Answer 9

Answer: Minor Groove is 3.4 A and Major Groove is 36 A. The width is 20 A

Question 10

Name 3 different Secondary Structures of RNA

Answer 10

Bulge, Internal Loop, Hairpin

Question 11

What causes a Hairpin Double Helix to form?

Answer 11

A strand of RNA Base Pairs with itself. The double stranded form of RNA adopts an A form double helix.

Question 12

How does UV light/Cosmic Rays Damage DNA?

Answer 12

Causes 10% of DNA damage. It causes bond breakage anywhere.

Question 13

Give 2 examples of how the deamination of amino groups can occur:

Answer 13

• Spontaneous Deanimation changing Cytosine to Urasil (usually repaired)
• Chemical like Nitrous Acid (from Nitrate preservative) and Bisulfite (from Anti-oxidant preservative) in food causing Cytosine to convert to Uracil and preventing base pairing and disrupting DNA. Moral of the story, don’t eat hot dogs.

Question 14

What forms a bend or kink in DNA?

Answer 14

Cyclobutane formation from UV light. This creates a Thymine dimer —he did not discuss this in the recitation review

Question 15

Given an example of Depurination

Answer 15