Enzymes

Question 1

How do enzymes catalyze the biochemical reactions?

Answer 1

By lowering the activation energy needed for the reaction.

Question 2

How do cofactors, coenzymes and inhibitors regulate the chemical reactions?

Answer 2

Competitively binding to the active site of the enzymes or non-competitively binding to the allosteric side of the enzyme.

Question 3

What is allosteric site of an enzyme?

Answer 3

Alternate part of the enzyme that non-substrate molecules bind

Question 4

Does enzymes change G of the reaction

Answer 4

No, bcuz they don’t change the free energy of the reactants or products, they only change the activation energy required to reach the transition state

Question 5

Which parts of the enzymes are very specific to substrates and why ?

Answer 5

Active sites of the enzymes, bcuz the R groups in amino acid chains of active sites have their specific properties, polar non polar acidic or basic…., the specificity of the enz to the substrates depend on the interaction of R groups and the substrates

Question 6

Why is optimal environmental ranges require for the enzyme catalyzed reactions.

Answer 6

Bcuz outside the optimal range, enzymes can reduce its capacity to bind to the substrates. And in extreme temp and pH enzymes can denature and lose their function

Question 7

What is the induced fit model of the enzyme catalyzed reactions?

Answer 7

Enzymes and substrates do not bind together instantly once they come together, there will be mild changes in enzyme’s active sites so that active sites of the enz and substrates will be fitted to each other perfectly.

Question 8

What is competitive inhibition?

Answer 8

Inhibitor molecules are very similar to substrate and competitively bind to the substrate binding site on the enzyme. So, substrate cant bind to the active site, the reaction is inhibited.

Question 9

What is allosteric inhibition?

Answer 9

Also called the non competitive inhibition. Inhibitor binds to the non active site of the enzyme, but change the configuration of the active site, thus reducing enzyme binding capacity to the substrate.

Question 10

How does competitive and non competitive inhibition differ?

Answer 10

Competitive inhibition affect the initial rate of reaction but does not affect the maximal rate whereas non competitive inhibitor affect the rate.

Question 11

What’s the mechanism of permacutical drugs?

Answer 11

Pharmaceutical drugs are inhibitors of certain enzymes in the body.
Statins drug group- inhibitors of HMG CoA reductase which synthesize cholesterol from the body lipids.

Question 12

What are cofactors?

Answer 12

Inorganic molecules such as iron, magnesium and zinc.

Question 13

What cofactors DNA polymerase needs in DNA replication?

Answer 13

Bound ZInc.

Question 14

What are coenzymes?

Answer 14

Organic molecules, made up oof carbon and hydrogen.

Question 15

What’s the common source of coenzyme?

Answer 15

Dietary vitamins. Vitamins can be precursors of coenzymes or function as coenzyme itself

Question 16

What are the names of cofactor and coenzymes that help in the catalysis of pyruvate dehydrogenase?

Answer 16

Cofactor—magnesium(Mg++)
Coenzymes-5 different kinds of coenzymes for the specific chemical reaction.

Question 17

How are substrates held to the active site of the enzymes?

Answer 17

By weak interactions such as hydrogen bonds and ionic bonds.

Question 18

Can enzymes catalyze in reversible reactions?

Answer 18

Yes, depending on which direction G is

Question 19

How can you overcome competitive inhibition?

Answer 19

By increasing the amount of substrates so that more conc of substrates can increase the chance of substrates binding to the active site.

Question 20

At the end of the reaction, enzymes concentration lowered. T or F

Answer 20

False. Enzyme are not consumed in a reaction

Question 21

What is the activation energy and transition state?

Answer 21

Activation energy- amount of energy required to reach the transition states,

Transition state- the state where the reactants can break the bonds and form the new bonds to produce products.

In exergonic reaction, heat is required to reach this transition state, where the reactants are most unstable and energy is released as heat after the products are formed

Question 22

Enzyme can catalyze both reversible reactions depending on the direction of ———

Answer 22

Delta G, free energy ———> exergonic reaction

Question 23

When the concentration of enzyme is full, addition of another substrate molecules is ——-

Answer 23

Uneffective, the only way to increase the rate of reaction is the addition of the enzymes

Question 24

The rate of reaction depends on ———-

Answer 24

The amount of the products released from the reactants

Question 25

The rate of reaction increases when the ——— increases.

Answer 25

Temperature, bcuz substrates collide more

Temperature but the temp must be within optimal range.

Extreme====> enzymes denaturation

Question 26

Enzyme inhibition are irreversible, t or f

Answer 26

Sometimes reversible, sometimes irreversible

Reversible ——-> bond to enxyme with the weak interactions

Irreversible- bond with covalent bonding

Question 27

Competitive inhibition can be overcome by ——-

Answer 27

Increasing the amount of substrate

Question 28

Penicillin block the enzyme that ———

Answer 28

Bacteria use to make cell walls

Question 29

Enzyme inhibition are always harmful

Answer 29

False. Drugs are enzyme inhibitors

Statin- inhibitor of cholesterol synthesis

Question 30

Enzyme mutations are always harmful.

Answer 30

False, some enzymes mutate in their active sites,———> bind to different substrate and catalyze a new reaction. If the new func benefits the organism, natural selection favor that process—-> enzymes persist in the population

Question 31

What is cooperativity

Answer 31

One substrate binds to the enzyme——> change the shape of other active sites in an enzyme——> stimulating other substrates to bind to that site

Cooperativity is considered to be allosteric activation bcuz substrate binding in its active site, is not the active site of other substrates.

Eg HB- one O2 binds to one subunit- the other subunits activity
increases and vice versa

Question 32

Can RNA act as enzymes

Answer 32

Yes. Ribozymes

Question 33

An enzyme can only bind one reactant at a time . T or F

Answer 33

False .
But typically binds to one substrate at a time only,

Question 34

Enzymes are specific to ————

Answer 34

Specific molecules only