Chemistry of Life

Question 1

Main classes of molecules

Answer 1

1. water
2. inorganic ions
3. small metabolites
4. lipids
5. polysacchrides
6. nucleic acids
7. proteins

Question 2

3 Main types of reactions

Answer 2

1. protonation/deprotonation
2. condensation/hydrolysis
3. oxidation/reduction

Question 3

ATP

Answer 3

• R group is the adenosine
• chemistry comes from phosphoester bond
• 3 waters coming out + 3 anhydride linkage
• ATP then loses 4 protons to become a negatively charged molecule

Question 4

Fats/Phospholipids

Answer 4

• glycerol + condensation reaction giving 3 waters + 3 ester bonds
• fatty acids + long hydrocarbon chains
• specific name of triglyceride
• phosphotydal ethanolamine: 2 hydroxyl groups of glycerol react with hydrocarbon. 1 links with phosphoric acid. phosphoric acid links with ethanolamine and 4 waters made

Question 5

Glucose

Answer 5

• Phosphate + glucose = water and glc-6-P
• phospho-ester bond
• glucose polymers have glycosidic linkages

Question 6

pH

Answer 6

pH = -log {hydrogen ions]

Question 7

Henderson Hasselbach Equation

Answer 7

Ka is the acid dissociation constant from HA = H + A
pKa = -log of Ka
pH = pKa + log [A]/[HA]

Question 8

Buffering

Answer 8

Substance that resists pH changes upon addition of small amounts of acid/base
Buffers work via Le Chatelier’s Principle if excess acid of alkali are added
Eq. is temporarily disturbed, but the position of equilibrium shifts to neutralise this
- Works best closest to its pKa
- pH of a buffer is independent of dilution

Question 9

Base Chemistry

Answer 9

Kb is the base dissociation constant

= [BH] [OH] / [B]

Question 10

The basis for determining which groups on biomolecules are charged

Answer 10

Henderson Hasselbach Equation

• use pKa of functional groups (ie. amino acids)
• physiological pH of 7.2
• work out ratio of protonated to unprotonated form to determine charge on molecule