7.2 Study Guide

Question 1

What are enzymes and what do they do?

Answer 1

Enzymes are proteins that help chemical reactions occur at a faster rate by lowering the energy needed for the reactions. First, the enzyme reacts with a substrate to form an enzyme-substrate complex (like a lock and key). Once this complex is formed, the substrate becomes a product or products and leaves the enzyme. The enzyme can then repeat the reaction with another substrate. The enzyme is shaped so it will react with only one specific substrate.

Question 2

What is a substrate?

Answer 2

the specific molecule that an enzyme acts upon to catalyze a chemical reaction

Question 3

Enzymes are Catalysts, what does that mean?

Answer 3

an enzyme being a catalyst means that the enzyme increases the rate of a chemical reaction without itself undergoing any permanent chemical change.

Question 4

What is an active site?

Answer 4

the specific region on an enzyme where a substrate molecule binds and undergoes a chemical reaction

Question 5

enzyme + substrate →

Answer 5

enzyme-substrate complex → enzyme + product 1 + product 2

Question 6

What is Activation Energy?

Answer 6

The amount of energy required to initiation a chemical reaction.

Question 7

What do enzymes do to the activation energy of a chemical reaction?

Answer 7

Enzymes lower the activation energy of a chemical reaction so less energy is needed for the reaction to occur

Question 8

Enzymes will usually perform one of two chemical reactions, what are they?

Answer 8

1) Dehydration Synthesis 2) Hydrolysis

Question 9

What is a substrate?

Answer 9

reactant that binds to an enzyme

Question 10

What is an active site?

Answer 10

where the substrate (reactant) fits into the enzyme when binding

Question 11

What are four properties of enzymes?

Answer 11

1) Reaction Specific 2) Not Consumed in the Reaction 3) Made of Protein (Sometimes RNA) 4) Affected by Cellular Reactions

Question 12

What does an “Enzyme is Reaction Specific” mean?

Answer 12

Each enzyme binds to a specific substrate (reactant).

Question 13

What does an “Enzyme is not consumed in a reaction” mean?

Answer 13

An enzyme is not destroyed by a reaction and can be part of many reactions.

Question 14

How would denaturation of the active site effect the function of an enzyme?

Answer 14

Disrupt the shape, making the active site not functional and the enzyme may lose the ability to catalyze reactions.

Question 15

Describe how the Enzyme Sucrase hydrolyzes the Substrate Sucrose.

Answer 15

1) An Enzyme-Substrate (Sucrase-Sucrose) complex is formed by Sucrose (substrate) binds to the active site on Sucrase (enzyme). 2) With H20 Sucrase (enzyme) catalyzes the hydrolysis of Sucrose (substrate) converting it into Glucose and Fructose (the products). Sucrase (enzyme) is released and available to catalyze another reaction.

Question 16

Most enzymes are named for the ________ they catalyze. And end in what suffix?

Answer 16

reaction; “-ase”

Question 17

What chemical reaction does the following enzyme type catalyze: sucrose synthase?

Answer 17

Breakdown of Sucrose into Sucrose and Glucose (sugars)

Question 18

What chemical reaction does the following enzyme type catalyze: Proteases?

Answer 18

Breakdown proteins into polypeptides or amino acids

Question 19

What chemical reaction does the following enzyme type catalyze: Lipases?

Answer 19

Breakdown fats into fatty acids and glycerol

Question 20

What chemical reaction does the following enzyme type catalyze: DNA Polymerase?

Answer 20

DNA Polymerase builds DNA molecules by adding nucleotides one by one to a growing DNA chain

Question 21

What chemical reaction does the following enzyme type catalyze: Pepsin?

Answer 21

Breaks down protein in food into smaller peptides and amino acids.

Question 22

What does an “Enzyme is affected by cellular conditions mean?

Answer 22

Enzymes are denatured by certain temperatures or concentrations of ions (pH , salinity)

Question 23

What is the “Induced Fit Model”?

Answer 23

Describes the Enzyme-Substrate interaction saying that the substrate binding to the enzyme causes it to change shape requiring less activation energy for the reaction.

Question 24

What are six factors that affect enzyme function?

Answer 24

1) Enzyme Concentration 2) Substrate Concentration 3) Temperature, PH, Activators, Inhibitors

Question 25

What are enzyme activators?

Answer 25

molecules that bind to enzymes and increase their activity

Question 26

What are enzyme inhibitors?

Answer 26

molecules that bind to enzymes and

Question 27

What is “Collision Theory”?

Answer 27

for an enzyme to catalyze a reaction - the substrate needs to physically collide with the enzyme’s active site in the correct configuration and with enough energy to make the enzyme-substrate complex and start. The more successful collisions, the faster the reaction rate will be.

Question 28

In Collision Theory when the temperature increases what happens?

Answer 28

When the temperature increases the rate of enzyme reactions increases because more collisions happen from increased molecular movement but too high a temperature can denature the enzyme.

Question 29

What can cause a protein (enzyme) to denature?

Answer 29

high temperatures, extreme pH levels and high salt concentrations (salinity)

Question 30

What happens to the reaction rate when the enzyme concentration increases?

Answer 30

The reaction rate increases as the enzyme concentration increases until the amount of substrate available is used then the reaction rate stays at a constant rate

Question 31

What happens to the reaction rate when the substrate concentration increases?

Answer 31

The reaction rate increases as the substrate concentration increases until the amount of enzyme available is used then the reaction rate stays at a constant rate

Question 32

What happens to the reaction rate when the temperature increases?

Answer 32

The reaction rate increases as the temperature increases until a temperature is reached that denatures the enzyme then the reaction rate decreases at a faster rate than it increased

Question 33

Do all enzymes function within the same temperature and pH ranges?

Answer 33

No, they function in different pH and temperature ranges.

Question 34

What is the maximum temperature human enzymes function at?

Answer 34

37 degrees Celsius

Question 35

What is the maximum temperature hot spring bacteria enzymes function at?

Answer 35

70 degrees Celsius

Question 36

What happens to the reaction rate when the pH increases within the functioning pH range of an enzyme (becomes more alkaline)? Decreases (becomes more acidic)?

Answer 36

The reaction rate increases as the pH increases until the optimal pH for that enzyme is reached then the enzyme denatures and the reaction rate decreases at the same rate than it increased. The reaction rate increases and the pH decreases until the optional pH for that enzyme is reached then the enzyme denatures at the same rate that it increased.

Question 37

What are Enzyme Cofactors and Coenzymes?

Answer 37

cofactors and are molecules that are needed for an enzyme to function properly (usually inorganic ions, not proteins) and coenzymes do the same but are usually vitamins

Question 38

Enzyme activators and cofactors do what to the shape of the enzyme?

Answer 38

maintain or change the active site shape

Question 39

What is competitive inhibition of enzymes?

Answer 39

Enzyme inhibition where an inhibitor (similar in structure to the substrate) binds to an enzyme’s active site and prevents the enzyme’s substrate from binding

Question 40

What is noncompetitive inhibition of enzymes?

Answer 40

Enzyme inhibition where an inhibitor binds to an enzyme at a site other than the active site (allosteric site), changes the shape of the enzyme and prevents the substrate from binding to the enzyme properly.

Question 41

Heavy metal poisoning is an example of?

Answer 41

Noncompetitive inhibition of an enzyme

Question 42

Can allosteric sites be used for enzyme activation or inhibition? Or both?

Answer 42

Both

Question 43

What happens to the reaction rate as the substrate increases when a competitive inhibitor is present?

Answer 43

As the substrate increases it can outcompete the competitive inhibitor for the activation site and the reaction rate will reach the maximum rate as normal before levelling off.

Question 44

What happens to the reaction rate as the substrate increases when a noncompetitive inhibitor is present?

Answer 44

As the substrate increases it cannot out compete the noncompetitive inhibitor because it binds to the allosteric site changing the enzyme activation site shape so the substrate cannot bind to the enzyme and the reaction rate levels off at a lower rate than it would have if the noncompetitive inhibitor was not there

Question 45

What is an endergonic reaction?

Answer 45

A chemical reaction that requires energy input to happen

Question 46

How would you maximize enzyme activity considering all of the factors discussed in class?

Answer 46

Increase temperature (not above denaturation), optimal pH for the enzyme, optimal salinity for the enzyme, Cofactors and Coenzymes present if needed, not having competitive or noncompetitive inhibitors present, high concentration of enzyme and substrate

Question 47

How would you minimize enzyme activity considering all of the factors discussed in class?