Foundations 3

Question 1

endogenous mechanisms for regulation of enzyme activity: 5 ways per enzyme molecule

Answer 1

competitive inhibition. allostery. reversible covalent modification. Ca ions. zymogens.

Question 2

endogenous mechanisms for regulation of enzyme activity: per cell?

Answer 2

induction of gene expression: long term regulation, increasing capacity or number of molecules

Question 3

per molecule mechanisms of regulating enzymes share a molecular basis?

Answer 3

somehow alter protein structure, which alters structure of active site and thus binding affinity

Question 4

competitive inhibition: reversibility?

Answer 4

reversible

Question 5

3 examples of pharmaceutical inhibitors of enzyme activity

Answer 5

methotrexate for chemo. penicillin. statins

Question 6

allostery: occurs in what protein? each protein exists in two?

Answer 6

proteins with quaternary structure aka more than one subunit. two distinct conformations, with high or low affinity for the substrates

Question 7

allostery and non-catalytic subunits example

Answer 7

cAMP binding to PKA: two regulatory subunits bound to two catalytic subunits

Question 8

reversible covalent modification example? which proteins?

Answer 8

phosphorylation/dephosphorylation: inorganic phosphate group attached to amino acid side chains in target protein with OH groups (Ser, Thr, Tyr)

Question 9

attachment/removal of phosphate group impacts what 3 things of the amino acid side chain

Answer 9

size, charge and polarity

Question 10

biological membranes are not a ____, but are?

Answer 10

not polymers: non covalent supramolecular assembly of lipids

Question 11

fatty acids: definition

Answer 11

long chain hydrocarbon carboxylic acids which vary in chain length and degree of saturation

Question 12

fatty acids: amphipathic?

Answer 12

part hydrophobic (fatty acyl tail) and hydrophillic (carboxyl head grou)

Question 13

fatty acids form ___ when mixed in water. why? structure?

Answer 13

micelles: spontaneously form because of the hydrophobic effect. hydrophobic tails in core, polar carboxylate head groups at surface

Question 14

saturated vs. unsaturated: melting temperatures?

Answer 14

saturated = higher MT like butter, unsaturated = oils

Question 15

fatty acid melting points: reflects?

Answer 15

extent of non-covalent interactions which depends on VdW interactions - saturated fatty acyl tails align better = higher melting temperature

Question 16

trans double bonds: shape?melting temperature? problem?

Answer 16

make the tail geometrically more like a saturated FA = greater melting temperature. metabolic problem: doesn’t fit into active site of enzyme

Question 17

fat: aka? stored where? structure?

Answer 17

triacylglycerols, stored in adipocytes, 3 FAs esterified to glycerol.

Question 18

hydrophobicity and storage?

Answer 18

hydrophobicity enables efficient storage (g/volume) because water is excluded.

Question 19

membrane lipids: all are made up of? common property?

Answer 19

all have a polar head group +2 fatty acyl tails esterified to it. all ampipathic

Question 20

cholesterol is a ____ . accounts for what % weight of plasma membrane? hydrophobic or philic?

Answer 20

steroid: 35%. highly hydrophobic