Biomolecules

Question 1

what are the properties of glucose?

Answer 1

1. free carbonyl group in linear form -> reducing
2. small size, many -OH -> can diffuse through phospholipid bilayer
3. pent/hexose -> more stable building blocks
4. isomerism (alpha, beta) -> various building blocks for diff molecules

Question 2

describe structure & function of glycogen & starch (amylopectin)

Answer 2

1. large molecule: insoluble -> don’t affect water potential of cell
2. alpha (1,4) GB within branch & alpha (1,6) GB at branch points: compact, helical, highly branched storage molecule w/ more glucose packed per unit volume
3. extensive branching: allows for more ends for hydrolytic enzymes to work on -> release more glucose per unit time
4. large amt of alpha glucose monomer: large energy storage -> glucose to be oxidised to give ATP

Question 3

describe structure and function of cellulose

Answer 3

1. alternative beta glucose monomers rotated 180 deg wrt e/o: forms straight, unbranded chain w/ -OH group pointing out in both directions, -> interchain H bonds -> form microfibrils w/ high tensile strength
2. macromolecule w/ decreased -OH groups for H bonds w/ H2O (interchain bond): insoluble -> do not affect wp
3. B(1,4) GB linking beta glucose monomers: requires rarely found hydrolytic enzyme, cellulase to protect integrity of cellulose cell wall

Question 4

how does triglyceride form?

Answer 4

1. 3 FA + non-polar,hydrophobic hydrocarbon chain joined to glycerol backbone -> form 3 ester linkages
2. each ester linkage form btw hydroxy & carboxyl group via condensation
3. removal of 1 H2O molecule per FA