Chapter 12: The Protein Catalyst

Question 1

What is an Enzyme?

Answer 1

is a specialized protein that speeds up or starts a chemical reaction without being changed by the reaction
- allows chemical reactions in the cells to happen fast enough to meet the new body’s need

Question 2

Thousands of enzymes in a cell each have a unique what?

Answer 2

They each have a unique function

Question 3

What is a Catalyst?

Answer 3

A catalyst is a substance that speeds up a reaction between substances without being affected by the reaction

Question 4

Enzymes are related to catalysts how?

Answer 4

Enzymes are a group of proteins that act as catalysts

Question 5

Why do cells only need a low concentration of many different enzymes to function?

Answer 5

Since enzymes do not change during chemical reactions, cells only need a low concentration of many different enzymes

Question 6

What is Activation Energy?

Answer 6

is the energy need to start a reaction

- enzymes lower the amount of energy needed to start a reaction

Question 7

What do Digestive Enzymes do?

Answer 7

Digestive enzymes decrease the amount of heat energy needed during digestion

Question 8

Enzymes are specific to what?

Answer 8

Enzymes are specific to the compounds with which they will react

Question 9

What is the Lock-and-Key Model?

Answer 9

1. Enzyme is compared to a lock
2. The key represents the substance being changed, known as the substance
3. The key must be inserted in the right spot in the right way
4. The keyhole, or active site, is where the substrates attaches to the enzymes

Question 10

The Lock-and-Key model is limited for what reason?

Answer 10

is limited by research indicating that the substrate does not turn when inserted into the active site and an enzyme is not a perfect match to the substrate

Question 11

What is the Induced-Fit Model?

Answer 11

The induced-fit model addresses the limitations of the lock-and-key model

Question 12

What happens in the Induced-Fit Model?

Answer 12

The active site temporarily changes the shape of the enzyme to allow the reaction to occur, then returns to its original configuration after the reaction

Question 13

All enzymatic reactions follow the same basic process, what are they?

Answer 13

1. Enzymes and substrate combine to form an enzyme-substrate complex
2. Enzyme-substrate complex is unstable and breaks apart, leaving the enzyme to act again on another substrate

Question 14

How do Coenzymes work?

Answer 14

1. By attaching to the enzyme and changing its shape so the substrate can fit in the active site
2. attaching to the substrate and changing its shape so it will fit the active site of the enzyme
3. acting as a transfer agent by accepting an atom or molecular group and transferring it to another compound

Question 15

Vitamins and minerals are important coenzymes including?

Answer 15

The B Vitamins, Calcium, Magnesium and Zinc

Question 16

What is the Nomenclature for enzymes (accepted in 1961)?

Answer 16

1. Enzymes are named for the types of reactions or substances for which they are the catalyst
2. The root name for the enzyme and the substrate are the same
3. Enzymes end in -ase

Question 17

What is the exception to this naming system for enzymes?

Answer 17

Some enzymes had already been identified before the new naming systems

Question 18

What are the 3 categories of digestive enzymes?

Answer 18

1. Proteases break apart proteins
2. Lipases break apart lipids
3. Carbohydrases break apart starches and sugars

Question 19

Some enzymes have more than one what?

Answer 19

Some enzymes have more than one name

Question 20

What is the other name for the Enzyme Sucrase?

Answer 20

Sucrase is also known as invertase because the mixture of glucose and fructose is often called Invert Sugar

Question 21

What is Water Availability and how does it apply to Enzymatic Reactions?

Answer 21

Water must be available to act as a reactant as well as a solvent in enzymatic reactions

Question 22

Lack of water does what to enzymatic activity?

Answer 22

The lack of water slows or stops enzymatic activity

Question 23

Enzymatic reactions will not occur in what kind of products?

Answer 23

Enzymatic reactions will not occur in dry products

- Water must be a reactant in the breakdown of carbohydrates, lipids, and proteins

Question 24

How does the concentration of a solution affect Enzyme Activity?

Answer 24

1. The more substrate in the solution, the greater the rate of the reaction is
2. The rate of enzymatic reaction increases as the concentration increases, up to the saturation point

Question 25

How does Temperature affect Enzyme Activity?

Answer 25

Heat increases enzyme activity, as in blanching vegetables before freezing

Question 26

How do Acids and Bases affect Enzyme Activity?

Answer 26

A pH that is too high or too low will denature an enzyme

Question 27

What are Electrolytes?

Answer 27

can prevent enzymes from reacting with a substrate

Question 28

What are Enzyme Inhibitor?

Answer 28

prevents enzyme-substrate complexes from forming

Question 29

What do Enzyme Inhibitors do?

Answer 29

1. Change the shape of the enzyme or the substrate

2. Help protect foods from bacteria and mold by stopping the digestive enzymes they release from working

Question 30

Where do Enzyme Inhibitors occur?

Answer 30

The occur naturally in a wide variety of foods from animal and plant sources

Question 31

How are Enzymes used by the food industry to develop food products?

Answer 31

1. Converting one food product into another, such as with milk to cheese
2. Extracting food components from food systems such as the separation of juice from insoluble residues
3. Playing a key role in developing ingredients

Question 32

What are the Positive Effects of Enzymes and the Food Supply?

Answer 32

1. Make food easier to eat
2. Preserve food
3. Improve flavour, quality, or appearance
4. Plays a role in fermentation

Question 33

What are the Negative Effects of Enzymes and the Food Supply?

Answer 33

1. Break down the structure of fruits and vegetables
2. Unpleasant flavour and odour changes
3. Undesirable changes in texture and colour

Question 34

Carbohydrases react with sugars and starches for commercial uses such as to…?

Answer 34

1. Make corn syrup and high-fructose corn syrup
2. Ferment wine and beers
3. Stabilize chocolate syrup
4. Clarify fruit juices

Question 35

Lipases are used to?

Answer 35

1. Extract unwanted egg yolk from egg white to improve the whipping properties of egg white
2. Improve flavour and texture of various products including cheese, ice cream, margarine, butter, and many baked goods

Question 36

Proteases are used to do what?

Answer 36

1. Tenderize meat by breaking long protein fibres, as in solutions for marinated meat
2. Reduce the size of proteins extracted from malt and grains during beer and ale production
3. Reduce mixing time
4. Increase pliability of dough
5. Change food into a different product, such as milk to cheese

Question 37

How do researchers uses enzymes to preserve food?

Answer 37

Ripe fruits and vegetables are stored in an oxygen-free environment to prevent deterioration by oxidases

Question 38

What is Enzymatic Browning?

Answer 38

Colour changes from enzymatic browning may be desirable for raisins or figs, but not sliced apples or pears

Question 39

How can we prevent browning of cut fruit, in the food industry?

Answer 39

Uses acids as enzyme inhibitors