Week4-Course2

Question 1

Grains and vegetables proteins are considered …… due to shortage in one or more essential amino acids

Answer 1

incomplete

Question 2

…… is a permanent denaturation that results when liquid or semi-liquid proteins form solid or semisoft clots

Answer 2

coagulation

Question 3

Proteins belonging to witch protein classes are soluble in water

Answer 3

globular

Question 4

Changes in the pH of a protein solution might lead to protein aggregation due to decreased …… between protein molecules.

Answer 4

electrostatic charges

Question 5

What are enzymes

Answer 5

Enzymes are a group of proteins that act as catalysts (substance that speeds up the rxn between substances)

Question 6

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

Answer 6

T

Question 7

…… is the energy needed to start a reaction

Answer 7

activation energy

Question 8

What are the two models to explain the functioning of enzymes

Answer 8

1. Lock and key model

2. Induced fit model

Question 9

what is the activation site?

Answer 9

The site where the substrate attach to the enzyme

Question 10

Why is the lock-and-key model limited?

Answer 10

Because doesn’t provide answer to the fact the enzymes and substrates that don’t have a match still yields products

Question 11

How does the induced-fit model addresses the limitations of the lock-and-key model?

Answer 11

In the induced-fit model the active site temporarily changed to accommodate the substrates and returns to original states afterwards.

Question 12

State the two step process explaining how enzymes work

Answer 12

1- enzyme and substrate form an enzyme-substrate complex

2-Enzyme-substrate complex is unstable and breaks apart so the enzyme can go elsewhere

Question 13

Names the vitamins and mineral that are co-enzymes mentioned in the course

Answer 13

vitamin B, calcium, magnesium and zinc.

Question 14

T or F : enzymes are exclusively named after the substances for witch they are catalyst

Answer 14

F, they can also be named after the types of reactions for which they are the catalyst (ex hydrolase)

Question 15

What is the root name for the enzymes?

Answer 15

The name of the substrate.

Question 16

What are the three categories of digestive enzymes (broad categories)

Answer 16

1. Lipase
2. Protease
3. Carbohydrase

Question 17

What is the other name of sucrase?

Answer 17

invertase

Question 18

____ is the loss of the carboxyl group as carbon dioxide gas

Answer 18

decarboxylation

decarboxylase

Question 19

____ is the loss of the amino group as ammonia gas by the action of the _____ enzyme

Answer 19

deamination

deaminase

Question 20

What is putrefaction?

Answer 20

General process by witch the proteolytic enzymes degrade the food (proteases and peptidase)

Question 21

What is Lipolytic rancidity

Answer 21

Off-flavors produced by the lypolysis of triglycerides that contains butyric acid. by the lipases

Question 22

What is the enzyme responsible for the rancidity

Answer 22

Lipoxygenases

Question 23

What cause the rancidity?

Answer 23

The addition of oxygen to the fatty acids of lipids by the enzyme lipoxygenases

Question 24

What are the factors that affect enzyme activity? (6) And what is the most important

Answer 24

1. Water availability (most important)
2. Substrate concentration of the solution
3. Temperature
4. Acids and bases
5. Electrolytes
6. presence of enzymatic inhibitors

Question 25

Why is dehydration a good method for the preservation of food

Answer 25

Because it decreases the enzymatic activity (can even stop it if there is no water)

Question 26

Name four positive effects of using enzymes in the food supply

Answer 26

1- make food easier to digest
2-preserve food
3-improve flavor, quality and appearance
4-plays a role in fermentation

Question 27

Name four positive effects of enzymes in the food supply

Answer 27

1- make food easier to digest
2-preserve food
3-improve flavor, quality and appearance
4-plays a role in fermentation

Question 28

Name three negative effects of enzymes in the food supply

Answer 28

1- break down the structure of fruit and veggies
2-unpleasant flavor and odor changes
3-undesirable changes in texture and color

Question 29

Name two function of lipase in the food production?

Answer 29

1- extract unwanted egg yolk from egg white to improve the whipping
properties of egg white
2-improve flavor and texture of various products including cheese, ice cream, margarine, butter, and many baked goods

Question 30

Name five function of proteases in the food production?

Answer 30

1-tenderize meat by breaking long protein fibers, 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 into cheese