Enzymes

Question 1

Enzymes function by…

Answer 1

lowering the activation energy of reactions

Question 2

Enzymes biochemically are:

Answer 2

Proteins
(except ribozymes)

Question 3

Catabolic enzymes

Answer 3

Breakdown reactions, usually generates energy

Question 4

Anabolic enzymes

Answer 4

Build up reactions, always use energy

Question 5

How do enzymes exhibit optical specificity?

Answer 5

They act only on the L-isomer of an amino acid or D-isomer of a sugar

Question 6

How do enzymes catalyze specific reaction or reaction types?

Answer 6

Exhibiting optical specificity

Question 7

Are enzymes used up in the reaction?

Answer 7

No

Question 8

Do enzymes alter the equilibrium constants?

Answer 8

No

Question 9

Do enzymes change the free energy for the reaction?

Answer 9

No

Question 10

Exergonic reactions

Answer 10

reactions with a –ΔG that spontaneously occur

Question 11

Endergonic reactions

Answer 11

reactions with a +ΔG that require energy input to occur

Question 12

Factors affecting the rates of enzyme catalyzed reactions:

Answer 12

Temperature
pH
Enzyme concentration
Substrate concentration
Inhibitors

Question 13

When temperature increases the rate of reactions…

Answer 13

increase, but at temperatures greater than 102 degrees F, proteins denature

Question 14

At temperatures below 98 degrees F, reaction rates…

Answer 14

slow down

Question 15

Example of an enzyme with an optimal pH in acid 1.5-2.0

Answer 15

pepsin in the stomach

Question 16

Example of an enzyme with a neutral optimal pH 7.3-7.4

Answer 16

carbonic anhydrase in RBC

Question 17

Example of an enzyme with an optimal pH in base 8.0-9.0

Answer 17

trypsin in small intestines

Question 18

Increasing both the enzyme and the substrate concentration will…

Answer 18

increase the rate of reaction until a maximum velocity of the reaction is reached

Question 19

What does the Michaelis-Menten curve describe?

Answer 19

the effects of substrate concentration on activity of many (not all) enzymes

Question 20

What does the Lineweaver-Burke plot determine?

Answer 20

Experimentally determines Km and Vmax

Question 21

What is the disadvantage of the Lineweaver-Burke plot?

Answer 21

small experimental error can result in large error in the graphically determined values

Question 22

What does the Eadie-Hofstee plot determine?

Answer 22

Experimentally determines Km and Vmax

Question 23

What is the advantage of the Eadie-Hofstee plot?

Answer 23

only one reciprocal

Question 24

Enzyme inhibition can be:

Answer 24

Competitive, non-competitive, or irreversible or poisons

Question 25

Competitive inhibitors include:

Answer 25

most enzymes

Question 26

Non-competitive inhibitors include:

Answer 26

Allosteric enzymes and Hemoglobin

Question 27

Where do competitive inhibitors bind?

Answer 27

At the catalytic or active site

Question 28

Where do non-competitive inhibitors bind?

Answer 28

At an allosteric site

Question 29

Is competitive enzyme inhibition reversible?

Answer 29

Yes

Question 30

Is non-competitive enzyme inhibition reversible?

Answer 30

Yes

Question 31

How do competitive inhibitors affect Vmax?

Answer 31

no effect

Question 32

How do non-competitive inhibitors affect Vmax?

Answer 32

decrease Vmax

Question 33

What do competitive inhibitor molecules look like?

Answer 33

an S

Question 34

What do non-competitive inhibitor molecules look like?

Answer 34

does not resemble an S

Question 35

How do competitive inhibitors affect Km?

Answer 35

increase Km

Question 36

Examples of irreversible enzymes or poisons

Answer 36

Heavy metals (silver, mercury), nerve gas, carbon monoxide (CO), cyanide (CN)