2.) Nucleotides, Nucleic Acids, and DNA

Question 0

What is the different between a nucleotide and a nucleoside?

Answer 0

Nucleotide has a phosphate group, nucleoside does not.

Question 1

Which nucleobases are the Purines? Pyrimidines?

Answer 1

Purines: Adenine and Guanine
Pyrimidines: Cytosine, Thymine, and Uracil

Question 2

What is the difference between a deoxyribonucleic acid and a ribonucleic acid

Answer 2

2’ OH is only present on the ribonucleic acid.

Question 3

For all nucleotides, the phosphate group is located at the ______ position.

Answer 3

5’

Question 4

DNA subunits along a single strand are connected via ______________ from the ____ position to the ____ position.

Answer 4

Phosphodiester linkages, 5’, 3’.

Question 5

Which basepairing forms 3 H bonds? 2H bonds?

Answer 5

3H Bonds: CG

2H Bonds: AT

Question 6

Describe the general structure of DNA.

Answer 6

Anti-parallel arrangement. Consists of Major grooves and minor grooves connected in succession. Directionality of a strand = 5’—>3’

Tightly compact as to exclude water from its interior.

3 forms:
A form: Right handed helix, condensed tightly
B form: Right handed helix, less compact
Z form: Left handed helix, least compact.

Question 7

What is the difference between a palindromic sequence and a mirror repeat sequence?

Answer 7

• Palindromic sequences* are on different strands. Therefore it has “two-fold” symmetry, and in order to superimpose each other, the strand requires 180 degree turns in two axes (vertically and horizontally, maybe see slide 21)
• Mirror repeats *are on the same strand. They only require one 180 degree turn to superimpose each other.

Question 8

Which can form specialized nucleic acid secondary structures, palindromic sequences or mirror repeats?

Answer 8

Palindromes: Hairpins (involves a single strand) or cruciforms (involves two strands).

Question 9

Melting temperature of DNA strands increases when _____________ increases.

Answer 9

The number of GC pairs.