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Biology > Enzymes Lab > Flashcards

Enzymes Lab Flashcards

1
Q

What is a Catalyst?

A

A catalyst speeds up the rate of a chemical reaction without being used up or changed in the process.

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2
Q

What does the Activation Energy do?

A

A reaction will occur more readily in the presence of a catalyst due to the lowering of the activation energy. This is an energy barrier that must be overcome for a reaction to proceed.

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3
Q

What are Enzymes?

A

Enzymes are biological catalysts that allow the chemical reactions of living organisms (metabolic reactions) to proceed smoothly and efficiently.

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4
Q

What are Enzymes usually consisted of?

A

They are usually Globular Proteins and tend to be highly specific in the reactions that they will catalyze.

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5
Q

How does each Enzyme work best?

A

Each kind of enzyme works best at the temperature and pH of its natural environment within the organism. Because of this each enzyme has both a thermal and pH optimum.

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6
Q

What does each Enzyme have?

A

A thermal and pH optimum.

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7
Q

What happens when a temperature exceeds the thermal and pH optimum in an enzyme?

A

Temperatures above this optimum progressively deactivate or denature the enzyme by changing the tertiary structure of the enzyme.

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8
Q

How do Enzymes work?

A

Because they are highly specific in the reactions that they will catalyze, each enzyme works best at the temperature and pH of its natural environment within the organism.

Each Enzyme has a Thermal and pH optimum because each kind of enzyme works best at the temperature and pH of its natural environment within the organism.

If the temperatures of the enzymes Thermal and pH optimum are above it, this causes the enzyme to deactivate or denature by changing the tertiary structure of the enzyme.

If temperature increases too much, this change becomes permanent - Irreversible Denaturation.

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9
Q

What happens when the temperature of an Enzyme increases too much?

A

The change then becomes permanent - Irreversible Denaturation.

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10
Q

How are lower temps and Denaturation related?

A

They don’t necessarily cause denaturation, but they do reduce the rate of reaction because enzymes and their substrates collide less frequently

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11
Q

How do enzymes get Inactivated?

A

By the pH values being above and below the optimal levels by altering the Hydrogen bonding of the alpha helix.

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12
Q

What element can block enzyme function

A

Mercury because it is a posion

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13
Q

How did Enzymes get discovered?

A

Scientists studying fermentation in the middle of the 19th century established the existence of enzymes

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14
Q

What were Enzymes known as?

A

They were known for many years as ferments (latin word for yeast)

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15
Q

When was the term Enzyme first introduced?

A

In 1878 from the Greek word meaning “in yeast”

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16
Q

What determines how many enzymes there are?

A

The more complex the organism, the more enzymes there are.

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17
Q

What is Bromelain?

A

Bromelain is a meat tenderizer that is a Proteolyic (protein splitting) enzyme which is extracted from papaya. Papain predigests part of the steak before you cook it.

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18
Q

What can lead to a tender tongue and why?

A

Fresh pineapple contains papin and when eaten could lead to a tender tongue

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19
Q

Why is fresh pineapple never used in making gelatin?

A

Because it will digest proteins that are necessary for setting of the product

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20
Q

How are enzymes useful for cleaning/getting out stains?

A

Specific laundry presoaks contain an enzyme that is extracted from bacteria. This is effecting in catalyzing the breakdown of protein based stains such as chocolate, coffee, meat, blood, etc.

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21
Q

What are some accidental discoveries of enzyme catalyzed reactions?

A

Production of wine and beer, formation of vinegar, leavening of bread, production of cheese.

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22
Q

What do Enzymes end in?

A

Ase

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23
Q

What is Cheese?

A

The solid portion curd of milk that has been separated from the liquid portion (whey)

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24
Q

What is the Curd consisted of?

A

Casein (protein) along with milk fat and other water insoluble substances.

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25
Q

What are the 2 different kinds of cheese?

A

Sour milk and Rennet Cheese

26
Q

What does controlled souring of milk allow?

A

Coagulation and separation of the whey from the casein, resulting in one form or another of sour milk cheese.

27
Q

How does Rennet cheese get produced?

A

Milk is coagulated or curdled by an enzymatic process. The enzyme used is extracted from the fourth stomach of unweaned calves, Rennin.

28
Q

What is Rennin secreted by?

A

Mucus membrane of the stomach during the first few weeks following birth, then gradually replaced by Pepsin.

29
Q

How do Rennin and Pepsin function?

A

They both function optimally in the acidic pH found in the calf’s stomach.

30
Q

How is Rennin obtained?

A

Obtained from the stomach of two to four week old calves in a brine extract called Rennet.

31
Q

How was cheese made previously?

A

By the addition of pieces of calf’s stomach to milk

32
Q

How long has calf rennet been commercially been produced?

A

Since 1874

33
Q

Why does Rennin have an advantage over all other proteolytic enzymes?

A

Because of its ability to coagulate milk

34
Q

What is Rennilase?

A

A bacterial enzyme that has been employed in the production of some kinds of cheese

35
Q

What is Kappa Casein?

A

One particular type of casein that functions to keep the other caseins in solution

36
Q

Why does Kappa Casein get broken apart?

A

It gets broken by two parts because its under the action of Rennet or Rennilase

37
Q

What happens when Kappa Casein gets broken apart in two by the action of Rennet or Rennilase?

A

The caseins precipitate out of the milk solution.

Leads to coagulation in which the casein proteins shorten - water is squeezed out and fat globules are trapped within the compacting mass.

38
Q

What was the cheese making procedure we did?

A
  1. Culturing (Acidifcation) This was completed by the lab technician by adding 20 ml of buttermilk added to each liter of milk while being cultured for at least four hours at 20 C.
  2. Coagulation: We used a hot plate to slowly heat the mixture to 32 C. Monitored the tip of the temperature in the milk of the milk, not touching the bottom of the beaker while stirring occasionally. When the milk is at 32 C, move the beaker from the hot plate to a nonconductive surface like a look. Now add 1 ml of rennet or rennilase, enzyme per 500 ml milk, and stir for one minute. Allow the beaker to sit undisturbed for about 30 minutes.
  3. Cutting: Cut the curd with wooden tongue depressor. One person should stir the curd gently with a tongue depressor for about 15 minutes. Use long slow movements. By doing this the curd will shrink and release the whey.
  4. Cooking: Heat the beaker slowly to 37-38C. Hold the temp for about 30 minutes by moving the beaker on and off the plate. Stir every 3-5 minutes.
  5. Firming: Removed beaker from heat, let stand for 5 minutes. Stir every 5-10 minutes.
  6. Draining: Pour the curds and whey through a double layer of cheesecloth. Squeeze out as much moisture as possible. Did this over a sink and discarded whey.
  7. Pressing: Squeeze the cheese in the cheesecloth in a ball to remove additional fluid. Remove the cheese and allow it to cool.
  8. Aging: Depending on the composition of the cheese and the presence of certain bacteria or fungi, the cheese will develop distinctive flavor as time goes by. Cheese generally becomes “sharper” with age. The flavorful products developed during aging include volatile fatty acids, ketones, esters, alcohols, esters, amino acids, ammonia, and hydrogen sulfide. Cheese that is intended to ripen for several months is generally dipped into wax to coat the surface. Wax retards water loss and reduces the oxidation process.
39
Q

How does cheese develop a distinctive flavor as time goes by?

A

Depending on the composition of the cheese and the presence of certain bacteria or fungi, the cheese will develop distinctive flavor as time goes by. Cheese becomes sharper with age.

40
Q

What products get developed during aging of cheese?

A

Fatty acids, ketones, esters, alcohols, esters, amino acids, ammonia, and hydrogen sulfide.

41
Q

What happens to cheese that is intended to ripen for several months and why?

A

Dipped into wax to coat the surface, because wax retards water loss and reduces the oxidation process.

42
Q

What were the purposes of this experiment?

A

The purposes were twofold. The first was to investigate the role of bile in the digestion of milk fat by pancreatic lipase.

Second purpose is to investigate the role of temperature in enzyme activity.

43
Q

Can bile alone hydrolyze (digest) lipids (yes or no)?

A

No

44
Q

Do the results indicate bile is helpful or necessary for fat digestion?

A

Helpful

45
Q

What is the pH value of lipase’s normal environment?

A

8

46
Q

Where in the body does the lipase we used normally function?

A

Duodenum

47
Q

How does Digestion differ from Emulsification?

A

Digestion is the chemical breakdown of large molecules into smaller ones, while Emulsification is the breaking down of large fat droplets into tiny droplets.b

48
Q

Are all catalysts enzymes (yes or no)

A

No

49
Q

Are all enzymes catalysts?

A

Yes

50
Q

Are enzymes usually globular proteins?

A

Yes

51
Q

The region of an enzyme that specifically fits the substrate is called the?

A

Active Site

52
Q

Where in the body does rennet normally function?

A

Stomach?

53
Q

Is the optimum pH for rennet acidic or basic?

A

Acidic

54
Q

Is coagulation and cooking done at 32-38 C because a. all enzymes function best at higher temperatures OR b this is the temperature of a calf’s stomach?

A

b

55
Q

Could lipase be substituted for rennet in cheese production?

A

No

56
Q

Is denaturation always reversible?

A

No

57
Q

Enzymes function a in all catalyzed cellular reactions or B primarily in digestion

A

A

58
Q

Something that speeds up the rate of a chemical reaction without being used up or changed in the process is called a

A

Catalyst

59
Q

Globular proteins that act as biological catalysts allowing the chemical reactions of living organisms to proceed smoothly and efficiently are called

A

Enzymes

60
Q

Breaking neutral fat molecules (neutral pH) into their component parts, fatty acids and glycerol, is called?

A

Digestion

61
Q

The chemical breakdown of a polymer into monomers by the chemical addition of water is called?

A

Hydrolysis

62
Q

The chemical reactions of living organisms are collectively called?

A

Metabolic Reactions

Biology (7 decks)

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