enzymes

Question 1

what do enzymes do

Answer 1

catalyse metabolic pathways

deficiency in function - leads to genetic disorder, accumulation of metabolites

Question 2

what are conjugated enzymes

Answer 2

enzymes with something else attached

cofacters - non protein component added eg ions, vitamins

most vitamins act as coenzymes

Question 3

describe oxidoreductases

Answer 3

adds or removes hydrogen ions in oxidation/reduction. can be used to detoxify alcohol from body

Question 4

describe transferase

Answer 4

transfers functional groups between donors and acceptors

Question 5

describe hydrolases

Answer 5

hydrolysis of substrates

Question 6

described lyases

Answer 6

add something (water, ammonia, co2) across a double bond, or remove presence to create double bond

Question 7

describe isomerases

Answer 7

isomerisation reactions

Question 8

describe ligases

Answer 8

catalyse reactions where 2 groups are joined using atp

Question 9

how does ph affect enzymes

Answer 9

affects r group charge, shape of active site, charge of substrate

Question 10

what is vmax

Answer 10

vmax is max speed of the reaction, active sites are saturated. vmax is never reached - asymptote

Question 11

what is Km

Answer 11

Km is the substrate concentration at half of vmax

a high Km - low affinity of enzyme to substrate
a low Km - high affinity of enzyme to substrate

Question 12

examples of function deficiency

Answer 12

lactose intolerance - lack of lactase, most have it, symptoms later. treated with tablets or avoiding milk

albinism - lack of tyrosinase leads to no melanin. little pigment in skin, hair, eyes

Question 13

describe reversible inhibition

Answer 13

competitive -
inhibitor binds to active site - competes with substrate
temporary
more substrate, less inhibition
increases Km, vmax same

non competitive -
inhibitor binds to other site
changes secondary and tertiary structure so substrate cant bind
Km same, vmax decreased

uncompetitive -
binds to the es complex, slow catalysis
Km decreased, vmax decreased

Question 14

describe irreversible inhibition

Answer 14

permanently deactivate enzyme

do not need to be similar shape to substrate

Question 15

what ways can enzyme activity be controlled

Answer 15

compartmentalisation
regulation by cell components
zymogens
covalent modification

Question 16

describe compartmentalisation

Answer 16

organelles have optimum conditions, protects against lytic (chopping) enzymes

Question 17

describe regulation by cell components

Answer 17

allosteric control - enzyme inhibited or promoted by small molecule

a positive effector increases activity, negative effector decreases
binding is cooperative - makes sigmoid graph

feedback control - regulation of allosteric enzyme. product in pathway activates or inhibits. ensures flux in pathways and creates sigmoid graph.

Question 18

describe zymogens

Answer 18

destroy tissue that produces them, so an inactive form is generated which can be activated when needed eg digestive enzymes or trysinogen

activation occurs through addition or removal to the molecule

Question 19

describe covalent modification

Answer 19

make or break covalent bonds between protein group and enzyme eg phosphate
this changes characteristics and conformation. if one form is active and the other is not - molecular switch ,reversible