Enzymes and Chemical Reactions

Question 1

exergonic

Answer 1

more energy released than absorbed

Question 2

endergonic

Answer 2

more energy absorbed than released`

Question 3

potential energy

Answer 3

energy stored in chemical bonds

Question 4

kinetic energy

Answer 4

energy being used. movement, light, sound

Question 5

activation energy

Answer 5

energy input needed to start a reaction

Question 6

catalyst

Answer 6

a substance that speeds up reaction rates without being used up

Question 7

catabolic

Answer 7

release energy by breaking up complex molecules

Question 8

anabolic

Answer 8

uses energy to create complex molecules

Question 9

how are enzymes biological catalysts

Answer 9

they are proteins that speeds up reaction rates in biological processes without being used up

Question 10

metabolism

Answer 10

sum of organism’s chemical reactions

Question 11

why are ender- and exer- gonic reactions often coupled

Answer 11

Because metabolism is the sum of these reactions

Question 12

Transition State

Answer 12

The transition state is when the bonds between molecules are at their weakest due to the potential energy being highest.

Question 13

what is an active site?

Answer 13

where the enzyme bonds with the substrate

Question 14

what bonds help bond the enzyme and substrate?

Answer 14

Hydrogen bonds
Ionic bonds
Hydrophobic interactions
Covalent bonds

Question 15

what are the 2 theories on how enzymes and substrates bond?

Answer 15

lock and key, and induced fit.

Question 16

what is lock and key?

Answer 16

It is a theory that enzymes are built geometrically and chemically to fit a substrate.

Question 17

what is induced fit?

Answer 17

It is a theory that an enzyme changes to fit the substrate

Question 18

What factors affect if a substrate can bond with a enyme?

Answer 18

competitive inhibitors, non-competitive inhibitors, and a change in pH or heat.

Question 19

How does substrate concentration affect enzyme reaction rates?

Answer 19

As substrate concentration increases, the reaction rate increases.
When the enzyme is saturated, the rxn rate will reach maximum.
It is saturated is when there are more substrates than enzymes.

Question 20

How does enzyme concentration affect enzyme reaction rates?

Answer 20

As enzyme concentration increases, the reaction rate increases(assuming substrate is abundant).
As enzymes increase, there are more collisions between substrates and enzymes, increasing the likelihood that an enzyme will collide.
There are theoretically no limits to the rate of rxn when adding enzymes, but in the body, the substrate becomes the limiting factor.

Question 21

How does temperature affect enzyme reaction rates?

Answer 21

As temperature increases, so does the rxn rate UNTIL the enzyme begins to unfold/denature. Every enzyme has an optimal temperature at which it works best. A Fever is created to denature bacteria when you are sick.

Question 22

How does pH affect enzyme reaction rates?

Answer 22

Every enzyme also has an optimal pH. This optimum is usually the pH where the enzyme functions in nature. Most mammals function best at a pH of about 7-8, similar to cellular environments.
Mouth = fairly neutral
Stomach = highly acidic
Small intestine = fairly basic

Question 23

What are cofactors and how do they affect enzyme reaction rates?

Answer 23

Many enzymes require the binding of smaller non-protein cofactors to function.Cofactors may be a small metal ion or vitamins.

Question 24

How do inhibitors affect enzyme reaction rates?

Answer 24

Enzyme inhibitors are chemicals which bind to enzymes and decrease the enzyme’s ability to catalyze its reactants.
Usually reversible, or can be irreversibly (covalent)

Question 25

what are non-competitive inhibitors

Answer 25

They bind (reversibly/irreversibly) to another part of the enzyme, causing protein to change shape making substrate catalysis less favorable.

Question 26

what are competitive inhibitors

Answer 26

They bind (reversibly/irreversibly ) to an enzyme’s active site and block the substrate from binding.

Question 27

what is a allosteric activator

Answer 27

Only On form has binding sites for both substrate and activator.
Activator locks enzymes in On form, making it easier for substrates to bind. Enzymes vibrate between Off and On.

Question 28

what is an allosteric inhibitor

Answer 28

The enzyme vibrates between Off and On forms. In the Off form of the enzyme cannot receive the substrate. The Inhibitor can bind and stabilize the off form. Allosteric inhibitors bind somewhere other than the active site and lock the enzyme into off form.

Question 29

what is negative feedback

Answer 29

Negative Feedback is when a molecule that occurs later in a metabolic pathway negatively affects a molecule earlier in the pathway. (inhibits)

Question 30

what is positive feed back

Answer 30

Positive feedback is when a molecule that occurs later in a metabolic pathway positively affects a molecule earlier in the pathway. (activates)

Question 31

what is positive feedfoward

Answer 31

Positive feedforward is when an earlier molecule affects a later one.(activates)