Enzymes

Question 1

amylase

Answer 1

converts starch into sugars

Question 2

thermophilic enzymes

Answer 2

heat tolerant

Question 3

standard free energy change /\G

Answer 3

difference between energy of reactants and products

Question 4

activation energy Ea

Answer 4

energy required to initiate the reaction

Question 5

Vmax

Answer 5

maximum rate of reaction - all enzyme active sites are full

Question 6

Km

Answer 6

Michaelis constant - 1/2 of Vmax
conc of substrate at which the rate of reaction is half its max value
measure of affinity
low Km = a high affinity

Question 7

Vi

Answer 7

initial rate of an enzyme catalysed reaction

Question 8

Michaelis menten plot

Answer 8

shows V (reaction rate) against [S] (substrate conc) and produces a hyperbolic curve

Question 9

line weaver burk plot

Answer 9

shows a straight line

intersection on x -axis = 1/Km, intersection on y-axis = 1/ Vmax

Question 10

feedback inhibition

Answer 10

when product of a metabolic pathway builds up it can act as an inhibitor to earlier stages in the pathway

Question 11

what is the most common covalent modification of enzymes

Answer 11

phosphorylation

Question 12

allosteric enzymes

Answer 12

multiple subunits and allosteric sites

do not conform to Michaelis menten plot of line weaver burk