Nutrition
• Why do we need food?
• Energy
• Provides raw materials for growth and repair
• Makes chemicals needed for metabolic reactions
• The 6 most common elements in food are:
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Carbon (C)
Hydrogen (H)
Oxygen (O)
Nitrogen (N)
Phosphorous (P)
Sulphur (S)
Other elements occur in smaller numbers:
5 as dissolved salts
• Sodium (Na)
• Magnesium (Mg)
• Chlorine (Cl)
• Potassium (K)
• Calcium (Ca)
3 as trace elements (only needed in tiny amounts):
• Iron (Fe)
• Copper (Cu)
• Zinc (Zn)
• The 6 groups of Biomolecules are:
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Carbohydrates
Lipids (Fats and Oils)
Proteins
Vitamins
Minerals
Water
Carbohydrates
Carbon (C), Hydrogen (H) & Oxygen (O)
• In the form of Cx (H2O)y
• Made of sugar units:
–Monosaccharides
–Disaccharides
–Polysaccharides
Monosaccharides
• Smallest unit of carbohydrate
• Sweet
• Soluble in water
• Glucose
• Fructose
Disaccharides
• Two monosaccharides joined together
• Sweet
• Soluble in water
• Sucrose (table sugar)=glucose + fructose
• Maltose=glucose +glucose
Polysaccharide
• Many monosaccharides joined together
• Insoluble in water
• Starch
• Cellulose
• Glycogen
Functions of Carbohydrates
• Provides energy (Metabolic Role)
• However if too many carbohydrates are
consumed it will be converted to fat and stored
• Cellulose in plant cell walls (Structural Role)
• Cellulose also has the function of preventing:
– Constipation
– High Blood Cholesterol
Lipids(Fats and Oils)
Carbon (C), Hydrogen(H) and Oxygen(O)
• Less oxygen than Carbohydrates
• Fats are solid at room temp, oils are liquid
• Lipid structure varies;
– Triglyceride(normal lipid): one glycerol with 3
fatty acids joined to it
– Phosopholipid: one glycerol, 2 fatty acids and a
phosphate group joined to it
Triglyceride
Functions of Lipids
• Lipids release energy in respiration (Metabolic
role)
• They also form a protective layer around delicate
organs such as the heart (Structural role)
• They act as an insulator, stored as adipose tissue
under the skin
• Lipids are insoluble in water but soluble in alcohol
• Sources of lipids include butter and cod liver oil.
Proteins
Carbon(C), Hydrogen (H), Oxygen (O) and Nitrogen (N)
• Made of amino acids joined together in
different ways
• 26 amino acids in total
• Dipeptide is a chain of 2 amino acids (think 2
marbles joined)
• Tripeptide is a chain of 3 amino acids
• Peptide is a chain of less than 20 amino acids
• Polypeptide is a chain of many amino acids
(apx 500)
• There are essential amino acids which cannot
be made by animals and must be consumed in
the diet (9 in total)
• Fibrous Protein: have very few or no foldings
e.g. keratin in hair and nails
• Globular Protein: have lots of foldings e.g.
Enzymes
• Prions are proteins that do not fold incorrectly
• Eg: Creutzfeldt–Jakob disease and BSE
Protein Functions
• Form enzymes and hormones (Metabolic Role)
• Present in hair, nails and muscle (Structural
Role)
Sources: Meat, Fish, Eggs and Nuts
Vitamins
• Most Vitamins cannot be made by the body
• Only needed in small amounts
• Water Soluble Vitamins: B group and C
• Fat Soluble Vitamins: A/D/E/K
Vitamin C
• Found in Oranges, forms connective tissue.
• Deficiency Scurvy: Bleeding gums, loose teeth
Scurvy
Vitamin D
• Found in Cod liver, for healthy bones.
• Deficiency Rickets.
Minerals
• Necessary in small amounts
• Form structures e.g. Calcium forms bones and
cell walls
• Forms soft body tissue e.g. Muscles
• Maintains concentration of cells and body
fluids
• Minerals needed by plants and animals vary.
• Animals:
• Calcium, found cheese, forms bones and teeth
• Iron, found in liver and green vegetables,
forms part of haemoglobin
• Plants:
• Calcium, absorbed from soil, forms calcium
pectate in cell walls
• Magnesium, absorbed from soil, is part of the
structure of chlorophyll
Water
• Water makes up the major body cells and
helps them to keep their shape
• It helps transport materials in and out of cells
• It is a good solvent
• Necessary for photosynthesis
Nutrient
Function
Source
Carbohydrates
•Sugars
•Starch
•Fibre
Energy
Energy
Prevents constipation
Sweets, fizzy drinks
Bread, potatoes, rice
Brown bread, fruit
Fats
Energy
Insulation
Butter, oil, cream
Proteins
Growth and repair
Meat, fish, eggs, nuts
Vitamins
•Vitamin C
Healthy skin and gums
Oranges
•Vitamin D
Strong bones
Dairy products
Minerals
•Iron
Haemoglobin which
Red meat, egg yolks
carries oxygen in blood
•Calcium
Strong bones
Milk, cheese
Water
Allows cells to work
Drinks, vegetables
2010 Section A Q1 Higher