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Biology GCSE > Enzymes And Digestion > Flashcards

Enzymes And Digestion Flashcards

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1
Q

What are enzymes

A

Protein molecules that act as biological catalysts. They speed up the rate of biological reactions, which takes place inside living cells, without being used up or change themselves.

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2
Q

Without enzymes what would happen

A

Most reactions in any living organism would occur to slowly for organisms to function

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3
Q

2 main types of reactions

A

Catabolic reactions

Anabolic reaction

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4
Q

What is a catabolic reaction

A

Break down large insoluble molecules into smaller, soluble molecules

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5
Q

Catabolic reaction example

A

Digestion and respiration

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6
Q

What is a anabolic reaction

A

Build up large molecules from smaller ones

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7
Q

Example of a anabolic reaction

A

Photosynthesis

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8
Q

What is a catalyst

A

A substance which increases the rate of a chemical reaction without being charged or consumed during the reaction.

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9
Q

What are enzymes made of

A

Enzymes are protein molecules and so are made up of amino acids

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10
Q

Most enzymes contain how many amino acids

A

100-1,000 amino acids

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11
Q

How are the different types of amino acids arranged

A

Joined in a long chain which is folded to produce a unique 3D Structure

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12
Q

Why is the shape so important of a enzyme

A

As it has a direct effect on how it catalyses the reaction

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13
Q

How is a enzymes shape determined

A

By the sequence of amino acids in its structure, and the bonds which form between the atoms of those molecules.

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14
Q

How do different enzymes have different shapes and functions

A

Because the order and type of amino acids in their structure is different

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15
Q

How are enzymes labelled

A

Depended on the substrate they work on. To name an enzyme the last 2-3 letters of the substrate’s name is replaced by the letters ‘ase’

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16
Q

What is amylase

A

The enzyme that catalyses starch and Amylose to produce Glucose

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17
Q

What is protease

A

The enzyme which catalyses proteins and produces amino acids

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18
Q

What is lipase

A

The enzyme which catalyses fats/lipids and produces Glycerol and fatty acids

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19
Q

What is carbohydrase

A

A enzyme which catalyses carbohydrates and produces simple sugars

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20
Q

Examples of substrates

A

Starch/amylose
Proteins
Fats/lipids
Carbohydrates

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21
Q

What is the molecule a enzyme works on

A

Substrate

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22
Q

The molecules formed in a enzyme reactions are

A

Products

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23
Q

What is the part of the enzyme the substrate binds to

A

The active site

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24
Q

What is the shape of the active site said to be

A

Complimentary to the substrate

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25
Q

All enzymes are substrate specific because they have a ……

A

Specific shape

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26
Q

At the active site what happens

A

That the enzyme reacts with its substrate, to break it down or put it together

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27
Q

Only .. substrate is the correct …….. to fit into the active site of an enzyme, therefore, enzymes can only catalyse 1 (or few) reaction(s). Hence, there are …….. of different types of ……. In the body to carry out all the ……….. reactions

A

1
Shape
1000s
Enzymes
Chemical

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28
Q

Enzyme actions steps

A
  1. Molecules constantly moving around (they have kinetic energy) and are constantly colliding with each other.
  2. When a substrate collides with a molecule of the right enzyme, it fits exactly into the active site. This is called an enzyme substrate complex.
  3. the reaction takes place and the products are released from the active site.
  4. This frees the active site for another substrate molecule to bind- the enzyme is not changed or used up by the reaction and so is available to repeat the action every time it collides with a substrate molecule.
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29
Q

How is the specificity of a enzyme explained

A

The lock and key theory

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30
Q

What does the lock and key theory propose

A

The active site has a complimentary shape (like a lock) into which only 1 specific substrate molecule (the key) fits exactly.

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31
Q

What is it called when the substrate molecule binds to a enzyme

A

A enzyme substrate complex

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32
Q

What happens after the enzyme substrate complex produces the products

A

The enzyme is released from the enzyme substrate complex ready for the next reaction

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33
Q

What are inhibitors

A

substances that interfere with enzyme action

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34
Q

What do inhibitors do

A

Fit loosely/partially into the active site preventing the substrate from binding

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35
Q

What do inhibitors lead to

A

A reduced (inhibited) rate of reaction

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36
Q

4 main factors affecting enzyme action

A

Temperature
pH
Enzyme concentration
Substrate concentration

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37
Q

What is the optimum

A

One particular temperature and pH that enzymes work best at

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38
Q

If the temperature and the pH changes sufficiently beyond a enzymes optimum what happens

A

The shape of the enzyme irreversibly changes

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39
Q

When the enzyme changes shape what happens

A

It will no longer work and will be considered denatured

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40
Q

Below optimum temperature what happenes

A

The enzyme and substrate have less kinetic energy and move slowly resulting in fewer collisions resulting in a Lower rate of reaction.

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41
Q

Increasing temperature causes

A

Increased kinetic energy of the molecules and the rate of reaction increases.

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42
Q

Optimum temperature is when

A

There is a maximum rate of enzyme activity

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43
Q

Above optimum temperature causes

A

A decrease in the activity of the enzyme because the shape of the active site alters (the enzyme is denatured)

44
Q

What does lower pH result in

A

More hydrogen ions in the solution. Which can interfere with the binding within an enzyme and thus affect the shape. Enzyme activity declines as the solution becomes more acidic or more alkaline. (Enzyme denatured)

45
Q

What does optimum pH cause

A

Highest activity of the enzyme because the shape of active site is most complimentary to the substrate

46
Q

Above or below optimum pH causes

A

Decrease in activity of the enzyme as it is denatured

47
Q

The more enzymes there are the faster the reaction. Why?

A

More active sites for the substrate to attach to, and so more frequent enzyme substrate collisions

48
Q

I’d there are too many enzymes what happens

A

If the rate level is off it means the substrate concentration is the limiting factor

49
Q

Enzymes used in commercial applications are

A

Thermo- stable

50
Q

What does thermo-stable mean

A

Work over a wide range of temperatures

51
Q

Example of enzyme commercial uses

A

Biological washing powder
Predigested food for babies
Extracting fruit juice from fruit (pectinase)
Softening centres of chocolate
Lactose free products (immobilised enzymes are used to remove lactose from milk.)

52
Q

Advantages of immobilising enzymes

A

Enzymes can be reused
The product is not contaminated with the enzyme (useful for the food and pharmaceutical industry)

53
Q

What is digestion

A

The process of breaking down large, complex, insoluble, food molecules into small, simple, soluble molecules, that can be absorbed into the blood in the ileum

54
Q

3 types of digestive enzymes

A

Carbohydrase - breaks down carbs into smaller sugars

Protease - breaks down protein into amino acids

Lipase - breaks fat into fatty acids and glycerol

55
Q

What is the digestive system composed of

A

The Alimentary (gut)

Which is a long tube with several organs attached to it.

56
Q

Where is the alimentary positioned and why

A

The alimentary canal runs from the mouth to the anus. The parts of the digestive system are organised so that different processes take place in different regions

57
Q

Where do the digested products go

A

Absorbed into the blood and transported around the body

58
Q

What is ingestion

A

Taking food into the alimentary canal

59
Q

What is digestion

A

Large, insoluble food molecules are broken down into simple, soluble molecules

60
Q

What is absorption

A

The passage of small, soluble molecules across the wall of the small intestine into the blood stream

61
Q

What is assimilation

A

Digested food molecules are absorbed into the body cells where they are used in respiration to release energy, stored or built up into new complex molecules.

62
Q

What is egestion

A

Passing out undigested food material from the anus

63
Q

Order of processes in digestive system

A

Ingestion
Digestion
Absorption
Assimilation
Egestion

64
Q

In the mouth …………………… …………. Occurs through ………. And ……… food by the teeth, breaking food into smaller pieces, increasing ……….. …….. for enzyme action

A

Physical digestion
Chewing
Grinding
Surface
Area

65
Q

Saliva function

A

Contains mucus to lubricate so it’s easy to swallow

Contains digestive enzyme salivary amylase which helps break down starch into glucose

66
Q

What is the oesophagus

A

The tube at the back of the throat food passes through before entering the stomach

67
Q

How does food pass through the oesophagus

A

By a wave of muscular contraction. This is called peristalsis

68
Q

What is the stomach

A

A muscular elastic bag

69
Q

What do the muscles do in the wall of the stomach

A

Contract rhythmically, mixing the food thoroughly, turning it into a thick liquid called CHYME

70
Q

What do glands produce in the stomach

A

Gastric juice

71
Q

What does gastric juice contain

A

Protease enzyme
Hydrochloride acid

72
Q

What is protease called in the stomach

A

Pepsin

73
Q

What does hydrochloric acid do

A

Makes stomachs contents very acidic (pH 1-3) which provides the optimum pH for pepsin functioning. Also kills many potentially dangerous microbes that enter along with food

74
Q

How long does food stay in the stomach

A

Food stays in the stomach for 3-4 hours before it is released in small quantities into the first part of the small intestine, called the duodenum

75
Q

What does the small intestine consist of

A

Duodenum and the ileum

76
Q

How long is the small intestine

A

Over 6metres long

77
Q

what does the duodenum do

A

Act upon the semi liquid food released from the stomach upon numerous secretions

78
Q

What are the secretions in the duodenum

A

Pancreatic juice
Intestinal juice
Bile

79
Q

How is pancreatic juice produced

A

By the pancreas and is secreted into the duodenum

80
Q

What does pancreatic juice contain

A

The enzymes:

Amylase
Protease
Lipase
Carbohydrase

81
Q

How is intestinal juice produce

A

By the walls of the duodenum

82
Q

What does intestinal juice contain

A

Amylase, protease, lipase, carbohydrase

83
Q

How is bile produced and stored

A

Green liquid produced in the liver and stored in the gall bladder.

84
Q

Functions of bile

A

It’s alkaline so it helps neutralise the acidic food

It emulsifies fat. This breaks down large fat globules into smaller fat globules. This increases the surface area for lipase enzymes to break fat down

85
Q

What happens in the ileum

A

More enzymes secreted (amylase, protease, lipase) to ensure all large molecules have been broken down to small molecules

86
Q

What happens to the small molecules in the ileum

A

Absorbed through the walls of the ileum into the blood = absorption. Occurs by diffusion

87
Q

Once in the blood stream where do the digested food molecules go

A

Carried around the body to where they are needed

88
Q

3 ways the ileum is adapted

A

Large surface area
Good blood supply
Thin and permeable membranes

89
Q

Why is it good for the small intestine to have a large surface area

A

Allows absorption to happen quickly and efficiently

90
Q

What would happen if the small intestine didn’t have a large surface area

A

A lot of digested food might pass out of the body without the chance of being absorbed

91
Q

What components does the small intestine have to have a large surface area

A

It’s very long (6metres)
It has folds and twists
The inner surface contains millions of microscopic finger like projections called villi

92
Q

What does each villus have

A

Its own network of blood capillaries

93
Q

What do the networks of capillaries in the small intestine connected to the villi do?

A

Transport the products if digestion (eg glucose) away from the small intestine once they’ve been absorbed and is replaced with blood low in digested food molecules .

94
Q

What does the good blood supply in the small intestine ensure

A

A steep concentration gradient

95
Q

Inside each villus is a structure called

A

A lacteal

96
Q

Instead of going into the blood capillaries fatty acids and glycerol are absorbed into the

A

Lacteal (a part of the system of tubes called the ‘lymph system’)

97
Q

How thick is the wall of each villus

A

1 cell thick

98
Q

How thick is the walls of the blood capillaries

A

1 cell thick

99
Q

How is the lining if each villus thin and permeable

A

It is permeable as the small number of cells between the lumen of the gut and the capillaries and lacteals

100
Q

Some food we eat is indigestible because we don’t have the correct ……. to digest it

A

Enzyme

101
Q

Most indigestible food is

A

Fibre (cellulose) from plant material

102
Q

The undigested food can’t be ……. In the ileum

A

Absorbed

103
Q

The indigestible food leaves the ileum and enters the

A

Large intestine (colon)

104
Q

What does fibre do

A

Helps food progress along the alimentary canal

105
Q

What happens in the colon

A

Water is absorbed from undigested food back into the blood; colon is adapted by having large surface area

106
Q

What happens in the rectum

A

The faeces is compacted and stored until it is egested

107
Q

What does the anus do

A

Faeces is egested through the anus every 12-24 hrs

Biology GCSE (7 decks)

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