3.5-3.6 Role of enzymes

Question 1

What is preventing spontaneous reactions from occurring rapidly such as a bag of sugar suddenly being converted to monosaccharides?

Answer 1

For chemical reactions to occur, established bonds need to be broken and new bonds need to be formed. For bonds to be broken, they first need to be strained, or made less stable which requires a small input of energy the initial energy investment required to start a reaction(the activation energy).

Question 2

transition state

Answer 2

molecules that gain the necessary activation energy occupies this stage and the bonds are unstable and ready to be broken.

Partial bump
Highest point of energy diagram

Question 3

catalyst (2)

Answer 3

a chemical agent that speeds up the rate of reaction without itself being chemically altered

-enzymes

Question 4

enzymes

Answer 4

increase the rate of reaction by decreasing the activation energy

Question 5

why does lowering the transition state result in a higher rate of reaction?

Answer 5

the rate of reaction is proportional to the number of reactant molecules that can get to the transition state

Question 6

Enzymes do not change the ____ of a reaction, enzymes do not ____ _____ to a reaction

Answer 6

free energy
supply energy

Question 7

each type of enzyme catalyses the reaction of only

Answer 7

a single type of molecule or a group of closely related molecules.

Question 8

active site (2)

Answer 8

the specific site on an enzyme where catalysis takes place

usually a pocket or groove

Question 9

induced fit theory (2)

Answer 9

When the substrate binds, it causes a noticeable change in the three-dimensional position of the amino acids at the active site. This brings the catalytic groups into the required position for catalysis to take place. A non- substrate molecule, even if it could bind, would not bring about the required change in the enzyme shape.

just before the substrate binds, the enzyme becomes even more precise in its ability to bind the substrate

Question 10

cofactor

Answer 10

a non protein group that binds very precisely to the enzyme

ex: iron, copper, zinc

Question 11

coenzymes

Answer 11

organic molecules that are derived from vitamins

Question 12

3 factors that enzyme use to reduce the activation energy

Answer 12

1. brining the reacting molecules together in the right orientation for catalysis to occur. Reacting molecules can assume the transition state only when they collide with sufficient energy and in the correct orientation
2. exposing the reactant molecules to altered charge environments that promote catalysis. In some systems, the active site of the enzyme may contain certain ionic groups whose positive or negative charges alter the substrate in a way that favour catalysis.
3. changing the shape of a substrate molecule. The active site may strain or distort substrate molecule into a conformation that mimics the transition state.

Question 13

inhibitors that bind to the actively site weakly usually through ______

Answer 13

noncolvalent interactions

Question 14

inhibitors that bind to the actively site are nonreversible if the bonding is

Answer 14

covalent bonding

Question 15

The inhibition of enzyme activity by a competitive inhibitor can be over come by

Answer 15

increasing the amount of substrate relative to inhibitor

Question 16

non competitive inhibitors

Answer 16

do not interact with the active site ut rather alter enzyme function by binding to another location on the enzyme

Question 17

in non competitive inhibitors, enzyme activity is controlled by

Answer 17

the reversible binding of a regulatory molecule to the allosteric site

Question 17

the rate of enzyme catalized reaction peaks at the temperature at which

Answer 17

kinetic motion is greatest but no significant unfolding of the enzyme has occurred