Nucleotides and Nucleic acids

Question 1

Describe the role of nucleotides

Answer 1

1. Precursors of RNA and DNA
2. High energy sources (ATP)- GTP, UTP, CTP- these all differ in nitrogenous bases but energy is between phosphate bonds
3. Regulatory signals (cAMP)- very potent as soon as it gets made it gets broken down
   - long term this reaction would drain energy to fast so isnt sustainable
4. Coenzymes (FAD, NAD, NADP)- all e- carriers
5. High energy intermediates in metabolism

Question 2

DNA

Answer 2

deoxyribonucleic acid

- stores genetoc info

Question 3

RNA

Answer 3

Ribonucleic acid
- carries genetic information
- catalytic function (behave as enzyme)
coronavirus= RNA virus

Question 4

Nucleosides

Answer 4

sugar- pentose

purine or pyrimidine

Question 5

Nucleotides

Answer 5

sugar
nitrogenous base
esterfied phosphates (one 2 or 3)
*the phosphate oxygens have pkas of abt 1.0 and 6.0 so are ionized at ph 7
- always deprotonated in cell
DNA and RNA will always have net negative charge

Question 6

How are nitrogenous bases attached to the sugar?

Answer 6

the bases are coupled to the C1’ of the sugar via a beta linkage with N9 of a purine or N1 of a pyrimidine

Question 7

Nucleotides as energy currency

Answer 7

the 5’ OH group of nucleotides can be esterified to pyrophosphate (PPi) (giving a nucleoside diphosphate) or triphosphate
ex- ATP

Question 8

What bonds hold the nucleotides?

Answer 8

Phosphodiester bonds linked 3’OH to 5’OH

nucleotide sequence is always written 5’3’

Question 9

How far apart are the bases? How does the helix rise

Answer 9

bases are 0.34nm apart

helix rises 3.6 nm in 1 turn= 10.5 base pairs

Question 10

Describe base stacking in DNA

Answer 10

Hydrophobic bases stack on top another in combination of van der walls and dipole-dipole interactions (weak but cumulative important)
- helps to minimize contact of bases with water (hydrophobic effect)
stacking is as important as H- bonding in stabilizing the helical structure