Food / Chemistry of Life

• Provide energy
• Growth and Repair
• Aid metabolism
• Aid continuity of life

• Iron FE
• Zinc ZN
• Copper CU

• Sodium NA
• Magnesium MG
• Chlorine CL
• Potassium K
• Calcium CA

• Carbon C
• Hydrogen H
• Oxygen O
• Nitrogen N
• Phosphorus P
• Sulphur S

• Carbohydrates
• Proteins
• Lipids- fats and oils
• Vitamins

• Anabolism: way energy is used to make large molecules from smaller ones using enzymes.
• Energy is absorbed.
• Example- photosynthesis

• Catabolism: where energy is released when larger molecules are broken down to smaller ones using enzymes.
• Energy is released.
• Example- respiration.

Catabolism is not the opposite of anabolism as pathways involved in each are different.

• The general formula for carbohydrates is Cx(H2O)y.
• Carbohydrates contain the elements- carbon, hydrogen and oxygen.
• Carbohydrates have twice as many hydrogen molecules as oxygen molecules.

• Sugars
• Starch
• Cellulose

• Monosaccharides:
• Properties- single sugar units,
• soluble in water,
• sweet to taste.

• Examples- glucose,
• fructose.

Source- Fruit.

• Disaccharides:
• Properties- 2 sugar units,
• Soluble in water,
• Sweet to taste.

• Examples- sucrose,
• lactose.

• Sources- table sugar,
• milk.

• Polysaccharides:
• Properties- many monosaccharides sugar units linked together,
• Not soluble in water,
• Doesn’t taste sweet.

• Examples- starch,
• cellulose.

• Sources- bread,
• pasta,
• cereals.

• Starch- In plants
• Glycogen- In animals

• Structural Role:
• Cellulose- found in plant cell walls.
• Chitin- found in fungal cell walls.

• Metabolic Role:
• Respiration- Glucose- immediate source of energy
• Photosynthesis- Glucose made from CO2 and water using the suns energy.

• Starch- In Plants
• Glycogen- In Animals

• Protein contains the elements- carbon, hydrogen, oxygen, nitrogen and may also have sulphur.
• Proteins are found in meat, fish, pulses and eggs.

• Proteins are made of long chains of amino acids.
• There are 20 common and several rare amino acids found in proteins.
• Peptide bonds join amino acids together to form polypeptide chains.
• The function of protein depends on the amino acids sequence and way they are folded.

• Denaturation is the reversible disruption of the 3-D shape of the protein.
• May be caused by heat, whipping, acids etc.
• If the protein happens to be an enzyme (all enzymes are proteins) then the enzyme will lose its activity.

• Structural Role:
• Keratin- found in skin, hair and nails.
• Myosin- protein in muscle
• Collagen- main component in connective tissue, tendons, ligaments and bone.

• Metabolic Role:
• Enzymes- are proteins and control chemical reactions in cells. eg. respiration, photosynthesis
• Hormones- regulate body functions. eg. insulin controls amount of glucose in the blood.

• Lipids are found in fat meat, dairy produce, vegetable oils.
• Lipids contain the elements carbon, hydrogen and oxygen.
• Has less oxygen molecules than carbohydrates.
• Fats are solid at room temperature.
• Oils are liquid at room temperature.
• Lipids are hygroscopic- insoluble in water.
• Are made up of a Glycerol and 3 Fatty Acids.
• Most common type of lipid is Triglyceride.
• Another type is phospholipids and they have same structure of fats but one of the fatty acid groups joined to the glycerol is replaced by a phosphate group.

• Structural Roles:
• Heat insulation- eg. under skin
• Protection- of organs around the body eg. heart.
• Cell membranes- phospholipids and lipoproteins are major components in cell membranes.

• Metabolic Role:
• Release energy in respiration.

• Vitamins are essential organic catalysts of metabolism.
• They’re needed in small amounts and cannot be produced by the body.
• Must be supplied continuously and in sufficient quantities.
• Vitamins are chemically different to one another.
• They’re made by plants and microorganisms but not animals (except vitamin D).
• Vitamins are Water soluble (B,C) or Fat soluble (A,D,E,K).

• Water soluble vitamin C:
• Food source- Citrus Fruit
• Cabbage
• Potatoes

Deficiency symptom- scurvy- bleeding gums, muscle and joint pains.

Function- basic constituent of collagen- necessary for connective tissue, bones, cartilage. Also stimulates defence mechanism of the body- white blood cells.

• Fat soluble vitamin D:
• Food source- fish liver oil,
• eggs,
• sun on skin produces vit D

• Deficiency symptom- Rickets in children
• Osteomalacia in adults

Function- stimulates absorption of calcium and phosphorus in the gut which is important for bone and teeth formation.

• Minerals are needed in small amounts.
• They form body structures (eg. calcium for bones)
• They form soft body tissue (eg. muscles)
• Minerals help enzyme/hormone activity.
• Common minerals in living organisms are - sodium, magnesium, chlorine, potassium, calcium, iron, zinc.

• Minerals needed by Plants: calcium and magnesium
• Calcium Function:
• Forms calcium pectate to make the middle lamella which holds the cell walls together.
• Magnesium Function:
• Needed in the chlorophyll structure which is necessary for photosynthesis.

• Minerals needed by Animals: calcium and iron.
• Calcium Function:
• Needed for bone formation.
• Iron Function:
• Necessary for the structure of the haemoglobin molecule which is involved in the transport of oxygen.

• Water is a major component of cytoplasm and body fluids.
• Water makes up 70-95% of cell mass.
• Acts as a universal solvent- therefore is a suitable medium in which chemical reactions can take place.
• Involved in the movement of materials in and out of cells.
• Water has a high thermal capacity- ie difficult to change its temperature.
• Can split to produce- O2, H and e <~ important in photosynthesis.