enzymes

Question 1

catalyst

Answer 1

substance that can change the rate of a reaction without being altered in the process

Question 2

enzyme

Answer 2

biological catalyst
Speeds up metabolic reactions by lowering the activation energy

Question 3

activation energy

Answer 3

energy needed to start reaction

Question 4

enzyme often ends in

Answer 4

-ase

Question 5

enzymes are in the form of

Answer 5

proteins

Question 6

do enzymes affect the change in free energy? how

Answer 6

no
they speed up reactions that would occur eventually

Question 7

substrate

Answer 7

The reactant that an enzyme acts on

Question 8

when is an enzyme-substrate complex formed

Answer 8

when The enzyme binds to its substrate

Question 9

active site

Answer 9

the region on the enzyme where the substrate binds

Question 10

where does a substrate bind to in an enzymatic reaction

Answer 10

active site

Question 11

how does the active site lower the activation energy barrier (4 ways)

Answer 11

Orienting substrates correctly
Straining substrate bonds
Providing a favorable microenvironment
Covalently bonding to the substrate

Question 12

substrate binding process (6 steps)

Answer 12

1. substrates enter active site
2. substrates held in active site by weak interactions
3. active site can lower activation energy and speed up a reaction
4. substrates are converted into products
5. products are released
6. active site is available for two new substrate molecules

Question 13

induced fit

Answer 13

ENZYME FITS SNUGLY AROUND SUBSTRATE – “CLASPING HANDSHAKE”

Question 14

an enzyme’s activity can be affected by:

Answer 14

temperature
pH
chemicals

Question 15

cofactors

Answer 15

non-protein enzyme helpers such as minerals (eg. Zn, Fe, Cu)

Question 16

coenzymes

Answer 16

organic cofactors (eg. vitamins)

Question 17

competitive inhibitors

Answer 17

binds to the active site of an enzyme, competes with substrate

Question 18

noncompetitive inhibitor

Answer 18

binds to another part of an enzyme → enzyme changes shape → active site is nonfunctional

Question 19

how does a cell regulate metabolic pathways?

Answer 19

switches on/off the genes that encode specific enzymes

Question 20

allosteric regulation

Answer 20

protein’s function at one site is affected by binding of a regulatory molecule to a separate site (allosteric site)

Question 21

activator

Answer 21

stabilizes active site

Question 22

inhibitor

Answer 22

stabilizes inactive form

Question 23

cooperativity

Answer 23

one substrate triggers shape change in other active sites → increase catalytic activity

Question 24

FEEDBACK INHIBITION

Answer 24

End product of a metabolic pathway shuts down pathway by binding to the allosteric site of an enzyme

Question 25

feedback inhibition prevents

Answer 25

wasting chemical resources

Question 26

feedback inhibition increases

Answer 26

efficiency of cell

Question 27

where are enzymes in cells?

Answer 27

wherever the most efficient position is. cell is compartmentalized and structures bring order to metabolic pathways. some enzymes are on particular membranes (mitochondria) or in fixed locations in the cell