Week4-Course2 Flashcards
Grains and vegetables proteins are considered …… due to shortage in one or more essential amino acids
incomplete
…… is a permanent denaturation that results when liquid or semi-liquid proteins form solid or semisoft clots
coagulation
Proteins belonging to witch protein classes are soluble in water
globular
Changes in the pH of a protein solution might lead to protein aggregation due to decreased …… between protein molecules.
electrostatic charges
What are enzymes
Enzymes are a group of proteins that act as catalysts (substance that speeds up the rxn between substances)
T or F : Since enzymes do not change during chemical reactions, cells only need a low concentration of many different enzymes
T
…… is the energy needed to start a reaction
activation energy
What are the two models to explain the functioning of enzymes
- Lock and key model
2. Induced fit model
what is the activation site?
The site where the substrate attach to the enzyme
Why is the lock-and-key model limited?
Because doesn’t provide answer to the fact the enzymes and substrates that don’t have a match still yields products
How does the induced-fit model addresses the limitations of the lock-and-key model?
In the induced-fit model the active site temporarily changed to accommodate the substrates and returns to original states afterwards.
State the two step process explaining how enzymes work
1- enzyme and substrate form an enzyme-substrate complex
2-Enzyme-substrate complex is unstable and breaks apart so the enzyme can go elsewhere
Names the vitamins and mineral that are co-enzymes mentioned in the course
vitamin B, calcium, magnesium and zinc.
T or F : enzymes are exclusively named after the substances for witch they are catalyst
F, they can also be named after the types of reactions for which they are the catalyst (ex hydrolase)
What is the root name for the enzymes?
The name of the substrate.
What are the three categories of digestive enzymes (broad categories)
- Lipase
- Protease
- Carbohydrase
What is the other name of sucrase?
invertase
____ is the loss of the carboxyl group as carbon dioxide gas
decarboxylation
decarboxylase
____ is the loss of the amino group as ammonia gas by the action of the _____ enzyme
deamination
deaminase
What is putrefaction?
General process by witch the proteolytic enzymes degrade the food (proteases and peptidase)
What is Lipolytic rancidity
Off-flavors produced by the lypolysis of triglycerides that contains butyric acid. by the lipases
What is the enzyme responsible for the rancidity
Lipoxygenases
What cause the rancidity?
The addition of oxygen to the fatty acids of lipids by the enzyme lipoxygenases
What are the factors that affect enzyme activity? (6) And what is the most important
- Water availability (most important)
- Substrate concentration of the solution
- Temperature
- Acids and bases
- Electrolytes
- presence of enzymatic inhibitors
Why is dehydration a good method for the preservation of food
Because it decreases the enzymatic activity (can even stop it if there is no water)
Name four positive effects of using enzymes in the food supply
1- make food easier to digest
2-preserve food
3-improve flavor, quality and appearance
4-plays a role in fermentation
Name four positive effects of enzymes in the food supply
1- make food easier to digest
2-preserve food
3-improve flavor, quality and appearance
4-plays a role in fermentation
Name three negative effects of enzymes in the food supply
1- break down the structure of fruit and veggies
2-unpleasant flavor and odor changes
3-undesirable changes in texture and color
Name two function of lipase in the food production?
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
Name five function of proteases in the food production?
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
