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GCSE - Biology > 3. Enzymes & Digestion > Flashcards

3. Enzymes & Digestion Flashcards

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1
Q

What are carbohydrates?

A

Molecules made up of units of sugar.

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2
Q

What are simple sugars?

A

Carbohydrates made up of only one or two units of sugar.

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3
Q

Give an example of a simple sugar.

A
  • Glucose -> One sugar unit

- Sucrose -> Two sugar units

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4
Q

What are large, complex carbohydrates?

A

Long chains of sugar units.

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5
Q

What is the difference between simple sugars and complex carbohydrates?

A

Simple sugars are made up of one or two sugar units, while complex carbohydrates are made up of long chains of sugar units.

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6
Q

Give an example of large, complex carbohydrates.

A
  • Starch

- Cellulose

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7
Q

What are lipids?

A

Fats and oils.

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8
Q

What are lipids made of?

A

Fatty acids and glycerol.

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9
Q

What does one lipid molecule contain?

A

1 molecule of glycerol joined to 3 fatty acid molecules.

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10
Q

What are proteins made up of?

A

Long chains of amino acids.

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11
Q

Why are protein chains folded into specific shapes?

A

It allows other molecules to fit into the protein.

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12
Q

What are the functions of proteins?

A

1) Antibodies
2) Hormones
3) Structural Proteins
4) Enzymes

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13
Q

How are proteins used as antibodies?

A

Help the body to fight disease as part of the immune system. They are produced by white blood cells.

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14
Q

How are proteins used as hormones?

A

Carry messages around the body.

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15
Q

How are proteins used as structural proteins?

A

Make up tissues in the body, such as muscles.

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16
Q

How are proteins used as enzymes?

A

Control chemical reactions in the body.

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17
Q

Why do chemical reactions in organisms have to be controlled?

A

To get the right amount of substances.

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18
Q

Why can organisms not just raise their temperature to increase the rate of desired reactions?

A
  • It would speed up unwanted reactions too

- The cells would be damaged at a certain temperature

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19
Q

What is a catalyst?

A

A substance which increases the speed of a reaction without being changed or used up.

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20
Q

What are enzymes?

A

Biological catalysts. They are protein chains folded into unique shapes.

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21
Q

What do enzymes reduce the need for?

A

High temperatures.

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22
Q

Do we have enzymes to speed up all reactions in our bodies?

A

No, only the useful reactions.

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23
Q

What is a substrate?

A

A molecule that is changed in the reaction. (i.e. The thing that gets broken down)

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24
Q

What does every enzyme have to bind onto a substrate?

A

An active site.

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25
Q

What is an active site?

A

The part of an enzyme where a substrate joins on.

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26
Q

How many types of reaction can an enzyme catalyse?

A

Usually only one.

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27
Q

Why can an enzyme usually only catalyse only 1 type of reaction?

A

The substrate has to be the correct shape to fit the active site.

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28
Q

What two factors affect the rate of an enzyme-catalysed reaction?

A

1) Temperature

2) pH

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29
Q

What effect does changing the temperature have on the rate of enzyme-catalysed reactions?

A

Increasing the temperature increases the rate of the reaction up until the optimum temperature. After that, the rate quickly decreases as the enzymes are denatured.

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30
Q

What does denatured mean?

A
  • When temperature or pH causes bonds to break in the enzyme and the active site to change shape.
  • This means the substrate doesn’t fit the enzyme anymore and the enzyme stops catalysing the reaction.
31
Q

What does optimum temperature mean (in terms of enzymes)?

A

The temperature at which they are most active.

32
Q

What is the optimum temperature for enzymes found in the human body?

A

Usually about 37*C.

33
Q

What effect does changing the pH have on the rate of enzyme-catalysed reactions?

A

If the pH is too high or too low, the enzymes are denatured.

34
Q

Do all enzymes have the same optimum pH?

A

No

35
Q

What is the optimum pH of pepsin and why?

A

pH 2, because it is found in the stomach, which is acidic.

36
Q

What do digestive enzymes do?

A
  • Break down big, insoluble molecules (starch, proteins, lipids) into smaller, soluble ones (sugars, amino acids, glycerol, fatty acids).
  • So that they can be absorbed into the bloodstream through the wall of the small intestine.
37
Q

What does amylase do and where does it work?

A
  • Breaks starch down into sugars

- In the mouth and small intestine

38
Q

Where is amylase made?

A

1) Salivary glands
2) Pancreas
3) Small intestine

39
Q

What does protease do and where does it work?

A
  • Breaks proteins down into amino acids

- In the stomach and small intestine

40
Q

Where is protease made?

A

1) Stomach (called pepsin there)
2) Pancreas
3) Small intestine

41
Q

What does lipase do and where does it work?

A
  • Breaks lipids down into fatty acids and glycerol

- In the small intestine

42
Q

Where is lipase made?

A

1) Pancreas

2) Small intestine

43
Q

Which organs/places produce which enzymes?

A

Pancreas -> Produces all 3
Small intestine -> Produces all 3
Salivary glands -> Produces amylase
Stomach -> Produces protease

44
Q

Where is bile produced?

A

In the liver.

45
Q

Where is bile stored?

A

In the gall bladder.

46
Q

Where is bile released?

A

Into the small intestine.

47
Q

What does bile do?

A

1) Neutralises stomach acid - It is alkaline and when it is released into the small intestine, it neutralises the hydrochloric acid from the stomach and makes conditions alkaline. This is optimum for enzymes found in the small intestine.
2) Emulsifies fat - It breaks fat into tiny droplets, increasing the SA for lipase to digest it.

48
Q

Where are enzymes used in the digestive system produced?

A

Glands and gut lining

49
Q

Diagram of the digestive system.

A

Pg 40 of revision guide

50
Q

Describe the path of food through the digestive system.

A

Salivary glands, Oesophagus, Stomach, Duodenum (+ Liver, Gall bladder and Pancreas release substances), Small intestine, Large intestine , Anus

51
Q

What is the duodenum?

A

The first section of the small intestine.

52
Q

What is the role of the salivary glands?

A

Produce amylase in saliva.

53
Q

What is the role of the oesophagus?

A

Connects the mouth to the stomach.

54
Q

What is the role of the stomach?

A

1) Churns the food with muscular walls
2) Produces protease (a.k.a. pepsin)
3) Produces hydrochloric acid to kill bacteria and to give the right pH for protease to work

55
Q

Why does the stomach produce hydrochloric acid?

A

1) To kill bacteria

2) To give the right pH for protease (pH 2)

56
Q

What is the role of the liver?

A

Produces bile (which neutralises stomach acid and emulsifies fat).

57
Q

What is the role of the gall bladder?

A

Stores bile before releasing it into the duodenum.

58
Q

What is the role of the pancreas?

A

Produces protease, amylase and lipase and releases them into the duodenum.

59
Q

What is the role of the small intestine?

A

1) Produces protease, amylase and lipase.

2) Where digested food is absorbed into the blood.

60
Q

What is the role of the large intestine?

A

Where water from food is absorbed into the bloodstream.

61
Q

What is the role of the anus?

A

Where faeces (mostly indigestible food) leaves the body.

62
Q

What is formed when an enzyme combines with a substrate?

A

Enzyme-Substrate Complex

63
Q

What is activation energy?

A

The energy required for a reaction to happen.

64
Q

Why are enzymes needed to break up some stains but not others?

A
  • Some stains are caused by soluble chemicals so they wash out easily.
  • Other stains are caused by insoluble chemicals so they have to be broken down (by enzymes) into soluble chemicals before they can be washed out.
65
Q

What are the general uses of enzymes in home and industry?

A
  • Biological detergents

- Changing foods

66
Q

What is the difference between biological and non-biological detergents?

A

Non-biological detergents - Contain chemicals that break up stains.
Biological detergents - Contain the same chemicals, but also contain a mixture of enzymes to break down insoluble stains.

67
Q

What makes enzymes ideal for use in biological detergents?

A

1) They break down animal and plant matter (so they can remove food and blood).
2) They work better at low temperatures (e.g. 30*C)

68
Q

Which enzymes are used in biological detergents and what do they break down?

A

1) Protease -> Blood and grass into amino acids

2) Lipase -> Butter and oil into fatty acids and glycerol

69
Q

What happens to enzymes after they are denatured?

A

They are recycled by the body as amino acids.

70
Q

In what ways are enzymes used to change foods in industry?

A

1) Protease - Pre-digesting proteins in baby foods to make them easier to digest.
2) Carbohydrase - Turning starch syrup into sugar syrup.
3) Isomerase - Turning glucose syrup to fructose syrup, which is sweeter and is used in slimming foods.

71
Q

How is protease used in home and industry?

A

1) Used in detergents to break down protein stains (e.g. blood, grass) into amino acids.
2) Used in pre-digesting of baby foods

72
Q

How is lipase used in home and industry?

A

Used in detergents to break down fat stains (e.g. butter, oil) into fatty acids and glycerol.

73
Q

How is carbohydrase used in home and industry?

A

Used to convert starch syrup into sugar syrup.

74
Q

How is isomerase used in home and industry?

A

Used to turn glucose syrup into fructose syrup, which is sweeter (so less sugar is needed to reach the same sweetness).

GCSE - Biology (11 decks)

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