Enzyme

Question 1

globular proteins that catalyse chemical reactions in living organisms

Answer 1

enzyme

Question 2

specific, increase rate of reaction, unchanged at the end of reaction

Answer 2

properties of enzymes

Question 3

metabolic reactions must reach this point to form products

Answer 3

activation energy En

Question 4

build molecules

Answer 4

anabolic reactions

Question 5

break down molecules

Answer 5

catabolic reactions

Question 6

lower the amount of activation energy needed, speeding up reactions, not used up or altered

Answer 6

how do enzymes work

Question 7

releases heat, gibbs free energy is negative

Answer 7

exergonic

Question 8

requires input of energy, gibbs free energy is positive

Answer 8

endergonic

Question 9

reactant for a specific enzyme

Answer 9

substrate

Question 10

interact with the substrate, causing physical stress in order to break bonds and create products, reducing activation energy

Answer 10

amino acid side groups

Question 11

depression in the surface of the globular protein where substrate binds

Answer 11

active site

Question 12

original model, goes straight from substrate + enzyme to enzyme substrate complex and enzyme + products

Answer 12

lock and key model

Question 13

active site is caused by folding, enzyme adjusts its shape to allow substrate to fit exactly into active site

Answer 13

induced fit model

Question 14

substrate and enzyme interacting, held together by hydrogen bonds and weak ionic interactions

Answer 14

enzyme substrate complex/transition state

Question 15

minimum amount of energy required to start the reaction

Answer 15

activation energy

Question 16

reduce the height of the energy barrier, lowering the activation energy required to start the reaction, increasing the rate of reaction

Answer 16

effect of enzyme on reaction

Question 17

factors that affect enzyme activity

Answer 17

temperature, pH, substrate concentration, enzyme concentration

Question 18

reaction rate increases as temperature increases within a temperature range towards optimal temperature

Answer 18

temperature

Question 19

enzyme denatures, loss of enzyme activity

Answer 19

above optimal temperature range

Question 20

enzyme is inactive

Answer 20

below optimal temperature range

Question 21

enzymes function best at an optimal pH, usually in the range of pH 6-8

Answer 21

pH

Question 22

if amount of enzyme is kept constant and substrate concentration is increased, reaction rate increases until it reaches max

Answer 22

substrate concentration

Question 23

when adding substrate has no effect because all enzymes are part of an enzyme substrate complex

Answer 23

substrate saturation

Question 24

if amt of substrate is kept constant and enzyme concentration is increased, reaction rate increases until it reaches a maximum

Answer 24

enzyme concentration

Question 25

when adding amount of enzyme has no effect on reaction rate because all substrate is bound

Answer 25

enzyme saturation

Question 26

receptor site that is close to but not directly on the active site of the enzyme

Answer 26

allosteric site

Question 27

shapes of enzymes (active/inactive) that enzymes will oscillate between

Answer 27

conformations

Question 28

chemicals that bind to specific enzymes and inhibit enzyme activity, important as enzyme activity must be controlled to coordinate cellular activities

Answer 28

enzyme inhibitors

Question 29

similar in shape to substrate and competes directly with substrate, binds to active site and inhibits enzyme function, can be overcome by increasing concentration of substrate

Answer 29

competitive inhibitor

Question 30

binds to allosteric site and inhibits enzyme activity by altering enzyme conformation, causing active site to change shape, preventing substrate binding shutting off enzyme activity

Answer 30

allosteric inhibitor

Question 31

chemicals that bind to active site/allosteric site and turn on/enhance/stimulate enzyme activity, allowing cellular activity coordination

Answer 31

activators

Question 32

binds to allosteric site of enzyme, altering conformation of the enzyme, causing active site to change shape, stabilizing conformation for the substrate, turning on/enhancing enzyme activity

Answer 32

allosteric activator

Question 33

substrate is activator and binds to active site, stabilizing conformation of the enzyme, allows additional active sites to bind more easily with substrate, turning on/enhancing enzyme activity

Answer 33

substrate activator

Question 34

inorganic ions (copper, zinc, iron) located in active site, attracting electrons from substrate, increasing binding ability between enzyme and substrate

Answer 34

cofactors

Question 35

organic non-protein molecules that are cofactors

Answer 35

coenzymes

Question 36

more permanent cofactors/coenzymes, bound more tightly, sometimes with a covalent bond to active site

Answer 36

prosthetic groups

Question 37

method of metabolic control where product formed later in sequence of reactions will allosterically inhibit an enzyme that catalyzes a reaction occurring earlier in the metabolic process

Answer 37

feedback inhibition