Lecture 12 - Nucleic Acids and Nucleotides

Question 1

Importance of Nucelotides

Answer 1

Precursors of nucleic acids - DNA and RNA
Precursors of energy carriers - ATP and GTP
Components of cofactors - NAD, FAD

Question 2

What are the Purine and Pyrimidine nucleotides?

Answer 2

Purine
- Adenine
- Guanine
Pyrimidine
- Cytosine
- Thymine
- Uracil

Question 3

Naming nucleotides in ribonucleotide and deoxyribonucleotide forms

Answer 3

Ribonucleotides (Base + Ribose + phosphate)

• Adenine = Adenylate
• Guanine = Guanylate
• Uracil = Uridylate
• Cytosine = Cytidylate

Deoxyribonucleotide (Base + deoxyribose + phosphate)

• Adenine = deoxyadenylate
• Guanine = deoxyguanylate
• Thymine = deoxythmidylate
• Cytosine = deoxycytidylate

Question 4

The DNA double helix is stabilised by…

Answer 4

H bonds between base pairs
Hydrophobic interactions of base pairs
Sugar-phosphate backbone interacting with water

Question 5

DNA Helix Conformations

Answer 5

DNA Helix A
- right handed
- short and broad
- 2.3 A, 23 A in diameter
- 11 bp per turn
- found in dehydrated conditions
DNA Helix B
- right handed 
- longer and thinner
- 3.4 A, 20 A diameter
- 10 bp per turn 
- major in vivo conformation
DNA Helix Z 
- left handed
- longest and thinnest
- 3.8 A, 18 A diameter
- 12 bp per turn
- found in GC rich regions