Ch 3 - Enzymes

Question 1

substances that speed up reactions without being permanently altered

Answer 1

catalysts

Question 2

energy input required to initiate a chemical reaction

Answer 2

activation energy

Question 3

reactants in an enzyme-catalyzed reaction

Answer 3

substrates

Question 4

particular binding site on an enzyme

Answer 4

active site

Question 5

typical suffix in the names of enzymes

Answer 5

“-ase”

Question 6

model that describes how the active site of an enzyme changes shape to tightly bind the substrate molecule

Answer 6

“induced fit” model

Question 7

enzyme that breaks down sucrose

Answer 7

sucrase

Question 8

enzyme that breaks down proteins

Answer 8

proteases

there are many specialized proteases - may also be called peptidase

Question 9

enzymes that break down lipids

Answer 9

lipase

Question 10

enzymes that build nucleic acid molecules by adding nucleotides to nucleic acid strands

Answer 10

polymerase

Question 11

How does enzyme concentration affect reaction rate?

Answer 11

As enzyme concentration increases reaction rate increases

more enzymes, more frequent collisions between enzymes and substrates

Question 12

How does substrate concentration affect reaction rate?

Answer 12

As substrate concentration increases reaction rate increases

more substrates, more frequent collisions between enzymes and substrates

Question 13

How does temperature affect enzyme function?

Answer 13

Optimum temp: greatest number of collisions.
Heat: speeds up molecular movement - but too much will “denature” the enzyme shape
Cold: molecules move slower - thus decreasing collisions
(all enzymes have an optimal temp)

Question 14

How does pH affect enzyme function?

Answer 14

changes in pH (H+ concentration) will disrupt bonding between enzymes and substrates.
changes in pH can also change the shape of the enzyme itself (thus changing the very specific shape of the active site)
(all enzymes have an optimal pH)

Question 15

Inorganic compounds that help enzymes function

Answer 15

cofactors

Question 16

Organic compounds that help enzymes function

Answer 16

coenzymes

Question 17

Compounds that reduce enzyme activity by blocking the enzyme’s active site

Answer 17

competitive inhibitor
(this is “competitive inhibition”)
compounds “compete” for active site so substrate cannot bind

Question 18

Compounds that reduce enzyme activity by binding to the enzyme (at allosteric site - other than active site) and change the enzyme’s shape

Answer 18

non-competitive inhibitor
(“non-competitive inhibition”)
this causes the active site to no longer be functional

Question 19

Inhibition in which the inhibitor permanently binds to enzyme by covalent bonding

Answer 19

Irreversible inhibition
(competitor=binds at active site)
(allosteric=binds to other "allosteric" site)

Question 20

Inhibition in which the final product of the pathway inhibits one of the earlier steps in the pathway

Answer 20

Feedback Inhibition

Question 21

An overall chemical reaction that is divided up into many small steps (a series of chemical reactions)

Answer 21

metabolic pathway
(this is the normal organization of the complex chemical reactions that drive live processes - each step typically involves its own specific enzymes)