1.3.1 Function of Food Why do we need food?. Need to know The Function of Food Three reasons for...
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Transcript of 1.3.1 Function of Food Why do we need food?. Need to know The Function of Food Three reasons for...
1.3.1 Function of Food
Why do we need food?
Need to know
• The Function of Food • Three reasons for requiring food
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Food is needed for:
1.Energy
2.Growth of new cells and Repair of existing cells, tissues, organs, etc.
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Food also supplies:
the materials and energy for the processes of:
1. Metabolism and
2. Continuity
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Learning check
Why do we need food?EnergyGrowth of new cells and Repair of existing cells, tissues, organs, etc.
What is metabolism?Metabolism is the chemical reactions that occur in the cells of living organisms
What is continuity?Continuity of life is the ability of an organism to exist from generation to the next
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1.3.2 Chemical Elements
Elements in Food
Need to know
• Chemical elements• Six common elements in food• Five elements in dissolved salts• Three trace elements
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What is Food made up of?
Food is made up of:
• Six chemical elementsC, H, O, N, P, S
• Salts of Na, Mg, Cl, K, Ca
• Three trace elements Fe, Cu, Zn 8
Chemical Elements and their Symbols
Calcium Ca Nitrogen N
Carbon C Oxygen O
Chlorine Cl Phosphorus P
Copper Cu Potassium K
Hydrogen H Sodium Na
Iron Fe Sulphur S
Magnesium Mg Zinc Zn9
1.3.3 Biomolecular Structures
Need to know
• Define Biomolecular Structures • State that simple biomolecular units are
composed of a combination of elements in different ratios e.g. carbohydrates Cx(H2O)y
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Types of FoodThe elements combine in different ratios to form
different food components (biomolecular units)
Food is made up of six different components
Water Proteins
Lipids Carbohydrates
Vitamins Minerals12
Humans are mainly made up of Water!
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CarbohydratesCarbohydrates contain the elements
Carbon Hydrogen Oxygen
The general formula for a carbohydrate is
Cx(H2O)y
There are twice as many hydrogen molecules as oxygen molecules
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Learning check
What are the six different food components?
Water Proteins
Lipids Carbohydrates
Vitamins Minerals
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A common carbohydrate
General formula = Cx(H2O)y
When x = y = 6We fet the formula C6H12O6
What is the name of this monosaccharide carbohydrate?
Glucose
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Another common carbohydrate
General formula = Cx(H2O)y
When x = 12 and y = 11We get the formula C12H22O11
What is the name of this disaccharide carbohydrate?
Sucrose
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Learning check
Name the three elements that make up carbohydrates
Carbon Hydrogen Oxygen
What is the general formula for a carbohydrate?
Cx(H2O)y
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1.3.4 Biomolecular Sources and the Components of Food
Need to know
• State that simple bio molecular units are composed of a combination of elements in different ratios e.g. carbohydrates Cx(H2O)y
• Name the element components, bio molecular components and sources of: carbohydrates, lipids and proteins.
• State that carbohydrates are composed of indivisible units and give examples of these e.g. – Monosaccharides – glucose; – Disaccharides – maltose; & – Polysaccharides – starch/cellulose. 20
Need to know
• What is a vitamin?• Name one water soluble vitamin. • Name one water in-soluble vitamin (fat-
soluble) • List the sources of these vitamins
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CarbohydratesCarbohydrates contain the elements
CarbonHydrogenOxygen
Usually in the ratio of 1C:2H:1O
They have twice as many hydrogen molecules as oxygen molecules
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3 Types of Carbohydrate
Monosaccharides
Disaccharides
Polysaccharides23
Monosaccharides
These are single sugar molecules simple sugarssoluble in watersweet to tastesmallest carbohydrate unit
Examples: glucose, fructoseFound in: fruit 24
O
C C
C C
C
C
Learning check
What are the elements that make up all carbohydrates?
Carbon Hydrogen Oxygen
Can you remember the general formula for a carbohydrate?
Cx(H2O)y 25
DisaccharidesThese are• two monosaccharide sugar units joined
together – known as double sugar molecules • soluble in water • sweet to taste
Examples: sucrose, lactose, maltoseFound in: table sugar, milk
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PolysaccharidesThese are• Many monosaccharide sugar molecules
joined together• Not soluble in water• Do not taste sweet
Example: starch, celluloseFound in: bread, pasta, cereals
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Learning check
Name the three types of carbohydrate
• Monosaccharides
• Disaccharides
• Polysaccharides
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Lipids
Lipids are a diverse group of substances which include
• fats (solid at room temp.)
• oils (liquid at room temp.)
• steroids which include cholesterol and some of the sex hormones
• waxes which cover insect bodies and plant leaves. 29
Structure of LipidsThey are made up of the elements
carbon hydrogen oxygen
But not have the same ratios as carbohydrates.
They are made up of two main types of moleculesFatty acids and Glycerol
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Learning check
Give examples and sources of:
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Examples Sources
Monosaccharides
Disaccharides
Polysaccharides
Glucose
Fructosefruit
Sucrose
Lactose
Table sugar
MilkStarch
Cellulose
Bread, Pasta,
Cereals
Types of Lipid
Two of the main types of lipids are
Triglycerides
Phospholipids
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Triglyceride
It is made up of
3 fatty acid molecules and 1 glycerol molecule
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This is the smallest lipid
Phospholipids
If one fatty acid of a lipid molecule is replaced by a phosphate group then a phospholipid is formed
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Sources of Lipids
• Fat – in and on meat
• Butter (80% fat)
• Cooking oils
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Learning check
The two main types of molecules that make up lipids are:
Fatty acids and Glycerol
The two main types of lipids are:TriglyceridesPhospholipids
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Proteins
Proteins contain the elements Carbon HydrogenOxygen Nitrogen
Some may also contain sulphur, phosphorous or iron
Proteins are found in lean meat, fish, pulses, soya and eggs 37
Structure of Proteins
Proteins are made up of long chains of amino acids
There are 20 common and several rare amino acids found in proteins
More amino acids are found in cells and tissues but are not in proteins
Amino acids are joined together by peptide bonds
This results in the formation of polypeptide chains 38
Amino Acids
All amino acids contain four distinct chemical groups connected to a central carbon atom:
• a single hydrogen atom • an amino group • a carboxyl group • a side chain
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Learning check
Proteins contain the elements Carbon HydrogenOxygen Nitrogen
Sometimes they contain sulphur, phosphorous or iron
Proteins are made up of long chains of amino acids
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Vitamins
Vitamins are essential organic catalysts of metabolism
• Needed in small amounts, cannot be produced in the body
• Must be supplied continuously and in sufficient quantities
• Differ from each other chemically
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Vitamins
We need Vitamins A, B, C, D, E and K in our diets to keep us healthy
Vitamins can be water soluble or fat soluble
Vitamins B and C are water soluble
Vitamins A, D, E and K are fat soluble
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Sources of Vitamins Vitamin Source
A Green leafy vegetables, Eggs, Cheese, Carrots
B Lean Meat, Cereals, Nuts
C Citrus Fruits, Green vegetables, Turnips
D Milk and Milk products, Sunlight
E Vegetable oils, fish, nuts
K Green leafy vegetables43
Learning check
What is a vitamin? A vitamin is an essential organic catalyst of
metabolismWhat vitamins dissolve in water?
B & CWhat vitamins are fat-soluble?
A, D, E and K
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END
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