Enzymes and Digestion Flashcards
1
Q
The Seven Food Groups :
A
- Carbohydrates
- Proteins
- Lipids (fats + oils)
- Fibres
- Vitamins
- Minerals
- Water
2
Q
Mnemonic to remember 7 food groups :
A
Cats protect little fish via Mr Wright
3
Q
Carbohydrates …
A
include simple sugar (monosaccharides) and complex sugars (polysaccharides such as starch which is made of thousands of glucose molecules)
4
Q
Glucose : Elements
A
C, H, O
5
Q
Glucose : Formula
A
C6H12O6
6
Q
Glucose :Function
A
Short term energy supply - used in respiration
7
Q
Glucose : Sources
A
e.g. fruits, sugars
8
Q
Starch : Elements
A
C, H, O
9
Q
Starch : Structure
A
1000s of glucose molecules
10
Q
Starch : Function
A
Long term energy storage - broken down into glucose for respiration
11
Q
Starch : Plants
A
Store starch
12
Q
Starch : Humans
A
Eat food containing starch, broken down into glucose in digestion
13
Q
Starch : Sources
A
e.g. bread, potato, pasta, rice
14
Q
Proteins : Elements
A
C, H, O, N, (S)
15
Q
Proteins : Structure
A
Chain of amino acids (20 different types)
16
Q
Proteins : Foods
A
e.g. meat, fish, eggs, dairy
17
Q
Lipids : Elements
A
C, H, O
18
Q
Lipids : Sub-units
A
glycerol + 3 fatty acids
19
Q
Lipids : Function
A
Long term energy storage
20
Q
Lipids : Types
A
Include fat (solid at room temperature) and oils (liquid)
21
Q
Lipids : Foods
A
e.g. butter, dairy, oil and nuts
22
Q
Fibre : Elements
A
C, H, O
23
Q
Fibre : Structure
A
1000s of glucose molecules
24
Q
Fibre : Plant
A
Make up plant cell walls (cellulose)
25
Fibre ; Humans
Cannot digest fibre but eating fibre helps to keep the digestive system healthy and prevent constipation
26
Fibre : Foods
e.g. vegetable, fruit
27
Minerals =
inorganic substances (salts) needed by the body in small amounts
28
Minerals : Example
calcium, iron, magnesium, iodine, etc.
29
Minerals : Functions
to make healthy bones (calcium) and blood (iron), etc.
30
Minerals : Foods
e.g. milk (calcium), meat and liver (iron)
31
Vitamins =
Organic substance needed by body in small amounts
32
Vitamins : Examples
Vitamin A, vitamin C, vitamin D
33
Vitamins : Function
To take part in important chemical reactions in the body
34
Vitamins : Foods
e.g. carrots (vitamin A), citrus fruits (vitamin C) and milk (vitamin D)
35
Water : Formula
H20
36
Water : Function
to carry substances around the body and replace lost water
37
Waters : Food
e.g. drinks, vegetable (cucumber, tomatoes)
38
Carbohydrates =
Short-term energy supply
39
Proteins =
Cell function, growth and repair of cells and tissues
40
Lipids =
Long-term energy storage and supply
41
Fibre =
To keep the digestive system healthy and prevent constipation
42
Vitamins =
To take part in important chemical reactions in the body
43
Minerals =
To make healthy blood, bones and other tissue
44
Water =
To carry substances around the body and replace lost water
45
Food Tests : Glucose (reagent)
Test using Benedict's reagent.
46
Food Tests : Glucose (colour change)
In presence of glucose will turn from blue to brick red, when HEATED
47
Food Tests : Starch (solution)
iodine
48
Food Tests : Starch (colour change)
Brown to blue/black
49
Food Test : Protein (reagent)
biuret reagent
50
Food Test : Protein (colour change)
light blue to purple
51
Balanced diet =
The right balance of different food groups providing the body with all essential nutrition and the right amount of energy (calories).
52
Malnutrition =
condition resulting from eating a diet that does not contain the right amount of nutrients.
53
Undernutrition + starvation =
not obtaining enough nutrient/calories
54
Causes for undernutrition + starvation:
not eating enough
55
Symptoms of undernutrition + starvation:
○ underweight ○ weakness o weight gain
56
Overnutrition + obesity =
taking too many nutrients/calories
57
Causes of overnutrition + obesity:
o overeating
| o genetic
58
Symptoms for overnutrition + obesity:
o weight gain
o excess fat o heart disease
o diabetes
59
BMI (body mass index) =
a measure of body fat based on height and weight
60
night blindness : causes
deficiency in vitamin A
| → degeneration of rod cells in retina
61
night blindness : symptoms
poor vision in low level lights
62
scurvy : causes
deficiency in vitamin C
63
survy : symptoms
* poor wound healing
* bleeding, particular in gums
* loss of teeth
64
rickets : causes
* deficiency in vitamin D or calcium
| * lack of sunlight
65
rickets : symptoms
• brittle bones
• bow legs
poor teeth
66
anaemia : causes
• deficiency in iron
67
anaemia : symptoms
* low energy levels
* lethargy
* dizziness
68
kwashiorkor : causes
• deficiency in protein
69
kwashiorkor : symptoms
* swollen belly
* poor muscle strength
* weight loss
70
goitre : causes
• deficiency in iodine
71
goitre : symptoms
* swollen lump in thyroid gland
| * slow metabolism
72
How much energy do we need
| depends on :
* activity levels
* temperature
* age
73
1 calorie =
quantity of heat energy required to raise the temperature of 1g of water by 1°c⁆ .quantity of heat energy required to raise the temperature of 1g of water by 1°c⁆ .
74
1 Joule =
4.2 x calories
75
food energy (calories) =
mass of water (g) x temperature rise (°c)
76
Using a calorimeter to determine the energy in food
First, the food is weighed, so we know the mass of it. The food is then placed and burned in a metal chamber that sits inside a well-insulated vessel of water. The food is lit using ignition wires.
The heat is released by burning the food is transferred to the water which surrounds the food chamber. The increase in temperature of the water, and the measured mass of both the food and the water are used to determine the heat released by the subsance.
77
Measuring the energy in food
1. First the food (organism used in the experiments) (the independent variable) is weighed so that we know the mass
2. The food is then placed and burned in a metal chamber with a known value of water surrounding the food chamber
3. Increase the temperature of the water and the change in the mass of both the food and water are used to determine the heat energy released by the substance - measuring the dependent variable
4. Repeat the experiment three times for accuracy
5. The energy (measured in calories) is then attained by multiplying the mas of water with the temperature rise.
78
Measuring the energy content of food in the lab : method
* Fill the boiling tube with 10cm3
* Measure the temperature at the start
* Measure the mass of food
* Mount food on mounted needle (or onto fireproof dish)
* Set fire to food into it until it is burned
* Hold burning food underneath water until it is burned
* Measure the temperature at the end
* Calculate energy in food
79
mouth :
starting point of digestion
80
teeth :
break up food particles mechanically in mouth
81
tongue :
mix food with saliva
82
oesophagus :
transport of food to stomach
83
stomach :
storage and digestion of food
84
duodenum :
main digestion of food
85
pancreas :
secretes digestive juices and enzymes
86
gall bladder :
site of bile salt storage
87
liver :
sit of bile salt production
88
ilieum :
main absorption of nutrients
89
large intestine :
absorption of water
90
rectum :
temporary storage of faeces
91
anus :
defecation
92
peristalsis =
a series of wave-like muscle contraction that moves food along the digestive system
93
How is food absorbed into the blood stream?
* the ileum is lined by thousands of villi
| * nutrients are absorbed into the bloodstream by diffusion
94
Absorption in the digestive system:
- Large SA
- Short diffusion distnace
- High concentration gradient
95
Absorption in the digestive system : Large SA:
○ Have villi on small intestine to increase SA
○ Stick out and increase SA
○ Thousands of villi and microvilli
96
Absorption in the digestive system: Short diffusion distance
○ Wall just one cell wall thick - ensures that there is only a short distance for absorption to happen by diffusion and active transport
○ Villi wall is thin and close to blood vessels
97
Absorption in the digestive system: High concentration gradient
○ Nutrient supply via peristalsis
| ○ Constant blood flow
98
digestion =
the breakdown of food
99
why does food need to be digested?
only small molecules can be absorbed (=diffuse) across villi into bloodstream
100
Types of digestion:
· mechanical digestion:
- teeth + tongue
· chemical digestion:
- enzyme
101
Enzymes =
proteins that speed up chemical reactions (for example the breakdown of food molecules)
102
Enzymes :
· each enzyme binds to a particular molecule (called their substrate) and breaks it down into produces
· without an enzyme the breakdown of a molecule would be much slower
103
enzymes are specific for a ...
```
particular molecule
(i.e. each enzyme can only bind to one type of molecule to break it down)
```
104
different enzymes are needed to ...
catalyse different reactions
105
starch is digested into
maltose and glucose by carbohydrate enzymes called amylase and maltase
106
protein is digested ...
into amino acids by the enzymes protease
107
lipid is digested into ....
glycerol and fatty acids by the enzyme lipase
108
Enzyme Names :
· start with the name of the molecule that the enzyme digests
. end in -ase
109
Testing the digestion of starch (CORMMSS)
Change : whether there are enzymes or no enzymes (with water)
Organism : 10g of bread, 10g of enzymes, 10ml of water
Repeat : repeat three times for accuracy
Measure : the digestion of starch/glucose produced
Measure : Benedict's reagent
Same : mass of bread (type of bread)
Same : volume of enzymes/ time left for / temperature / pH
110
enzymes catalyse catabolic ....
(breaking down) reactions
111
enzymes catalyse anabolic ...
(building up) reactions
112
Enzymes speed up biochemical reaction up to
10**6 times
113
Enzymes work by
lowering the activation energy (= energy needed to start a chemical reaction
114
Enzyme specificity :
· each enzyme binds to a particular molecule (=substrate) and catalyses the conversion into the product(s)
· enzymes are specific for a particular substrate (i.e. each enzyme can catalyse only one particular reaction
· different enzymes are needed to catalyse different reaction
115
lock and key model =
fits like a key into a lock
116
enzymes is an ....
amino chain of proteins
117
Enzyme action : Lock and Key Model
· substrate binds to active site
· enzyme - substrate complex forms
· reaction takes place
· product no longer fits into the active site and is released
· enzyme is free to be used again
(note : enzymes are not used up / changed during reaction)
118
Effect of temperature on enzyme activity : below optimum temperature
· rate of reaction increases as temperature increases
· more kinetic energy
. more collisions and more enzyme-substrate complexes
119
Effect of temperature on enzyme activity : optimum temperature
. highest rate of reaction (around 37° ⁆in humans)
120
Effect of temperature on enzyme activity :
| above optimum temperature
· rate of reaction decreases rapidly
· enzyme denatures
· active site changes shape
121
Effect of pH on enzyme activity : optimum pH
. highest rate of reaction
122
Effect of pH on enzyme activity : below / above optimum pH
· rate of reaction decreases rapidly
· enzymes denature
. active site changes shape
123
Digestion of food : Step One
In the mouth, starch digested into maltose by the enzyme carbohydrase(amylase) made in the salivary glands.
124
Digestion of food : Step Two
· in the stomach, protein digested into amino acids by the enzyme protease (pepsin) made in the stomach lining
· the stomach is very acidic (pH 2-3) and so pepsin works best at a low pH
125
Digestion of food : Step Three (Starch)
in the duodenum, starch is digested into maltose and glucose by amylase made in the pancreas and maltase made in the duodenum.
126
Digestion of food : Step Three (Protein)
· in the duodenum, protein is digested into amino acids by the enzyme protease (trypsin) made in the liver
127
Digestion of food : Step Three (Lipids)
· in the duodenum, the lipids are digested into glycerol and fatty acids the enzyme lipase made in the pancreas
· lipase action is helped by bile produced in the liver and stored in the gall bladder
128
Bile :
· bile neutralises the pH when the food exits the stomach
| · bile emulsifies (breaks down) lipids into droplets which increase the surface area helping lipase action
129
Starch : Broken down into :
Maltose & Glucose
130
Starch : Enzymes Involved
. Carbohydrase (amylase)
| . Carbohydrase (amylase + maltase)
131
Starch : Location of Digestion
. Mouth
| . Duodenum
132
Protein : Broken down into
Amino acid
133
Protein : Enzymes Involved
Protease (pepsin (stomach), trypsin (duodenum))
134
Protein : Location of Digestion
Duodenum
135
Lipids : Broken down into
Glycerol + fatty acids
136
Lipids : Enzymes Involved
Lipase
137
Lipids : Location of Digestion
Duodenum
