Enzymes And Digestion Flashcards
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.
2
Q
Without enzymes what would happen
A
Most reactions in any living organism would occur to slowly for organisms to function
3
Q
2 main types of reactions
A
Catabolic reactions
Anabolic reaction
4
Q
What is a catabolic reaction
A
Break down large insoluble molecules into smaller, soluble molecules
5
Q
Catabolic reaction example
A
Digestion and respiration
6
Q
What is a anabolic reaction
A
Build up large molecules from smaller ones
7
Q
Example of a anabolic reaction
A
Photosynthesis
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.
9
Q
What are enzymes made of
A
Enzymes are protein molecules and so are made up of amino acids
10
Q
Most enzymes contain how many amino acids
A
100-1,000 amino acids
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
12
Q
Why is the shape so important of a enzyme
A
As it has a direct effect on how it catalyses the reaction
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.
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
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’
16
Q
What is amylase
A
The enzyme that catalyses starch and Amylose to produce Glucose
17
Q
What is protease
A
The enzyme which catalyses proteins and produces amino acids
18
Q
What is lipase
A
The enzyme which catalyses fats/lipids and produces Glycerol and fatty acids
19
Q
What is carbohydrase
A
A enzyme which catalyses carbohydrates and produces simple sugars
20
Q
Examples of substrates
A
Starch/amylose
Proteins
Fats/lipids
Carbohydrates
21
Q
What is the molecule a enzyme works on
A
Substrate
22
Q
The molecules formed in a enzyme reactions are
A
Products
23
Q
What is the part of the enzyme the substrate binds to
A
The active site
24
Q
What is the shape of the active site said to be
A
Complimentary to the substrate
25
All enzymes are substrate specific because they have a ……
Specific shape
26
At the active site what happens
That the enzyme reacts with its substrate, to break it down or put it together
27
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
1
Shape
1000s
Enzymes
Chemical
28
Enzyme actions steps
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.
29
How is the specificity of a enzyme explained
The lock and key theory
30
What does the lock and key theory propose
The active site has a complimentary shape (like a lock) into which only 1 specific substrate molecule (the key) fits exactly.
31
What is it called when the substrate molecule binds to a enzyme
A enzyme substrate complex
32
What happens after the enzyme substrate complex produces the products
The enzyme is released from the enzyme substrate complex ready for the next reaction
33
What are inhibitors
substances that interfere with enzyme action
34
What do inhibitors do
Fit loosely/partially into the active site preventing the substrate from binding
35
What do inhibitors lead to
A reduced (inhibited) rate of reaction
36
4 main factors affecting enzyme action
Temperature
pH
Enzyme concentration
Substrate concentration
37
What is the optimum
One particular temperature and pH that enzymes work best at
38
If the temperature and the pH changes sufficiently beyond a enzymes optimum what happens
The shape of the enzyme irreversibly changes
39
When the enzyme changes shape what happens
It will no longer work and will be considered denatured
40
Below optimum temperature what happenes
The enzyme and substrate have less kinetic energy and move slowly resulting in fewer collisions resulting in a Lower rate of reaction.
41
Increasing temperature causes
Increased kinetic energy of the molecules and the rate of reaction increases.
42
Optimum temperature is when
There is a maximum rate of enzyme activity
43
Above optimum temperature causes
A decrease in the activity of the enzyme because the shape of the active site alters (the enzyme is denatured)
44
What does lower pH result in
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
What does optimum pH cause
Highest activity of the enzyme because the shape of active site is most complimentary to the substrate
46
Above or below optimum pH causes
Decrease in activity of the enzyme as it is denatured
47
The more enzymes there are the faster the reaction. Why?
More active sites for the substrate to attach to, and so more frequent enzyme substrate collisions
48
I’d there are too many enzymes what happens
If the rate level is off it means the substrate concentration is the limiting factor
49
Enzymes used in commercial applications are
Thermo- stable
50
What does thermo-stable mean
Work over a wide range of temperatures
51
Example of enzyme commercial uses
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
Advantages of immobilising enzymes
Enzymes can be reused
The product is not contaminated with the enzyme (useful for the food and pharmaceutical industry)
53
What is digestion
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
3 types of digestive enzymes
Carbohydrase - breaks down carbs into smaller sugars
Protease - breaks down protein into amino acids
Lipase - breaks fat into fatty acids and glycerol
55
What is the digestive system composed of
The Alimentary (gut)
Which is a long tube with several organs attached to it.
56
Where is the alimentary positioned and why
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
Where do the digested products go
Absorbed into the blood and transported around the body
58
What is ingestion
Taking food into the alimentary canal
59
What is digestion
Large, insoluble food molecules are broken down into simple, soluble molecules
60
What is absorption
The passage of small, soluble molecules across the wall of the small intestine into the blood stream
61
What is assimilation
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
What is egestion
Passing out undigested food material from the anus
63
Order of processes in digestive system
Ingestion
Digestion
Absorption
Assimilation
Egestion
64
In the mouth …………………… …………. Occurs through ………. And ……… food by the teeth, breaking food into smaller pieces, increasing ……….. …….. for enzyme action
Physical digestion
Chewing
Grinding
Surface
Area
65
Saliva function
Contains mucus to lubricate so it’s easy to swallow
Contains digestive enzyme salivary amylase which helps break down starch into glucose
66
What is the oesophagus
The tube at the back of the throat food passes through before entering the stomach
67
How does food pass through the oesophagus
By a wave of muscular contraction. This is called peristalsis
68
What is the stomach
A muscular elastic bag
69
What do the muscles do in the wall of the stomach
Contract rhythmically, mixing the food thoroughly, turning it into a thick liquid called CHYME
70
What do glands produce in the stomach
Gastric juice
71
What does gastric juice contain
Protease enzyme
Hydrochloride acid
72
What is protease called in the stomach
Pepsin
73
What does hydrochloric acid do
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
How long does food stay in the stomach
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
What does the small intestine consist of
Duodenum and the ileum
76
How long is the small intestine
Over 6metres long
77
what does the duodenum do
Act upon the semi liquid food released from the stomach upon numerous secretions
78
What are the secretions in the duodenum
Pancreatic juice
Intestinal juice
Bile
79
How is pancreatic juice produced
By the pancreas and is secreted into the duodenum
80
What does pancreatic juice contain
The enzymes:
Amylase
Protease
Lipase
Carbohydrase
81
How is intestinal juice produce
By the walls of the duodenum
82
What does intestinal juice contain
Amylase, protease, lipase, carbohydrase
83
How is bile produced and stored
Green liquid produced in the liver and stored in the gall bladder.
84
Functions of bile
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
What happens in the ileum
More enzymes secreted (amylase, protease, lipase) to ensure all large molecules have been broken down to small molecules
86
What happens to the small molecules in the ileum
Absorbed through the walls of the ileum into the blood = absorption. Occurs by diffusion
87
Once in the blood stream where do the digested food molecules go
Carried around the body to where they are needed
88
3 ways the ileum is adapted
Large surface area
Good blood supply
Thin and permeable membranes
89
Why is it good for the small intestine to have a large surface area
Allows absorption to happen quickly and efficiently
90
What would happen if the small intestine didn’t have a large surface area
A lot of digested food might pass out of the body without the chance of being absorbed
91
What components does the small intestine have to have a large surface area
It’s very long (6metres)
It has folds and twists
The inner surface contains millions of microscopic finger like projections called villi
92
What does each villus have
Its own network of blood capillaries
93
What do the networks of capillaries in the small intestine connected to the villi do?
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
What does the good blood supply in the small intestine ensure
A steep concentration gradient
95
Inside each villus is a structure called
A lacteal
96
Instead of going into the blood capillaries fatty acids and glycerol are absorbed into the
Lacteal (a part of the system of tubes called the ‘lymph system’)
97
How thick is the wall of each villus
1 cell thick
98
How thick is the walls of the blood capillaries
1 cell thick
99
How is the lining if each villus thin and permeable
It is permeable as the small number of cells between the lumen of the gut and the capillaries and lacteals
100
Some food we eat is indigestible because we don’t have the correct ……. to digest it
Enzyme
101
Most indigestible food is
Fibre (cellulose) from plant material
102
The undigested food can’t be ……. In the ileum
Absorbed
103
The indigestible food leaves the ileum and enters the
Large intestine (colon)
104
What does fibre do
Helps food progress along the alimentary canal
105
What happens in the colon
Water is absorbed from undigested food back into the blood; colon is adapted by having large surface area
106
What happens in the rectum
The faeces is compacted and stored until it is egested
107
What does the anus do
Faeces is egested through the anus every 12-24 hrs
