Enzymes

Question 1

General Info about Enzymes

Answer 1

• All enzymes are proteins, but not all proteins are enzymes
• Biological catalysts that consist of complex protein structures
• speed up or slow down reactions by lowering the activation energy

Question 2

What does catalyst mean

Answer 2

• Tend to speed up reactions

Question 3

Why are enzymes important to biological systems?

Answer 3

• Because other factors that increase reaction rate (such as temp or concentration) are also known to denature biological proteins

Question 4

Important note about enzymes

Answer 4

• Enzymes do not get used up in reactions themselves
• They are reusable

Question 5

Substrate

Answer 5

• A molecule or compound that is acted upon by the enzyme
• It often fits into the entire enzyme itself and fits in the active site
• Ex. Starch

Question 6

Active Site

Answer 6

• The physical opening in which the substrate attaches

Question 7

Induced Fit Model

Answer 7

• Model explains how some substrates are able to alter and improve the shape of an active site so that the enzyme functions better

Question 8

What does the induced fit model suggest?

Answer 8

That the “lock and key fit” is not necessarily accurate

Question 9

Cofactors

Answer 9

• Inorganic substances that aid in the enzyme’s function
• Minerals
• Ex: Ca2+, Na+, Mn2+

Question 10

Coenzymes

Answer 10

• Organic substances that aid enzyme function
• Ex: Any type of vitamin

Question 11

Allosteric Sites

Answer 11

• Receptor sites on an enzyme where the controlling molecule can plug in and affect enzyme function

Question 12

What is a receptor site?

Answer 12

A site on a membrane of a molecule where small attachments can join

Question 13

Graph A

Answer 13

• Linear reaction/relationship
  -As the enzyme concentration increases so does the rate of reaction

Question 14

Graph B

Answer 14

• Curved graph
• When the substrate concentration is too high, active sites get saturated since enzyme stays the same
• Substrate concentration gets too high when you over eat

Question 15

3 ways to control enzyme functions

Answer 15

1. Competitive Inhibitors
2. Allosteric Regulators
3. Feedback Inhibition

Question 16

Competitive Inhibitors

Answer 16

• Molecules that mimic substrate molecules and end up blocking the normal substrate
• Makes competition for the active site
• This can slow down or sometimes stop enzyme function

Question 17

Note about competitive inhibitors

Answer 17

• Can be a natural occurrence but it can also happen because of toxins that enter cell’s

Question 18

Allosteric Regulators

Answer 18

Molecules that bind to allosteric sites of an enzyme

Question 19

What are the two types of allosteric regulators?

Answer 19

1. Non-competitive inhibitors
2. Allosteric Activators

Question 20

Activator

Answer 20

Turn on enzymes

Question 21

Inhibitor

Answer 21

Turn off enzymes

Question 22

Noncompetitive Inhibitors

Answer 22

• Inhibit the enzymes from functioning by having a non-substrate molecule attach to an allosteric site so that the enzyme no longer functions

Question 23

Example of an artificial noncompetitive inhibitor

Answer 23

Pesticide DDT

Question 24

Allosteric Activators

Answer 24

• Molecules that bind to allosteric sites of enzymes and can alter the protein conformation
• Inactive enzymes become activated and the new active site becomes more stabilized

Question 25

Feedback Inhibition

Answer 25

• Process by which an enzyme is inhibited by a product that has formed after a series of other enzymatic reactions
• Self-regulating
• If the end product accumulates in high quantities, it will inhibit the first enzyme

Question 26

Note about feedback inhibition

Answer 26

Good way of regulating the production of molecules so you don’t make too much of a product within a cell

Question 27

Example of feedback inhibition

Answer 27

ATP allosterically inhibits more making of itself