Food

• Nutrition

  The way in which an organism obtains and uses food
• Function of food

  Source of energy, to make chemicals needed for metabolic reactions, growth and repair
• Metabolism

  The sum of all the chemical reactions in an organism
• 6 common elements

  Carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), sulphur (S)

  
• 5 elements present in dissolved salts

  Sodium (Na) magnesium (Mg) chlorine (Cl) potassium (K) calcium (Ca)
• 3 trace elements

  Iron (Fe) copper (Cu) zinc (Zn)
• Biomolecules

  Are chemicals that are made inside a living thing
• Carbohydrates

  Carbon hydrogen oxygen Cx(H2O)y

  Twice as much hydrogen

  C6H12O6

  
• Monosaccharides

  Single sugar unit

  Sweet to taste

  Soluble in water
• GLUCOSE

  Monosaccharide with formula C6H12O6

  Found in fruit sweets chocolate

  Made in photosynthesis

  
• Fructose


  Monosaccharide found in fruits.
• Disaccharides


  Sweet to taste

  Soluble in water

  Two monosaccharides joined together
• Sucrose (table sugar)


  Disaccharide (Glycose + fructose)

  
• Maltose


  Disaccharide (Glucose + glucose)

  
• Lactose (milk)


  Disaccharide (Glucose + galactose)
• Polysaccharides


  Insoluble in water

  Not sweet to taste

  Many monosaccharides joined together
• Starch


  Stored in plants

  Long chain of glucose

  Easily digested (glucose molecules joined together in a straight line)

  Rice potatoes flour

  
• Cellulose


  Not easily digested due to cross bonding

  Used as a fibre in diet

  Very strong cell walls

  
• Glycogen


  Stored by animals in the liver and muscles
• Structural carbohydrate


  Cellulose used to form plant cell walls.
• Lipids


  Carbon hydrogen oxygen

  Very little oxygen

  Fats solid at room temperature

  Lipids liquid at room temperature
• Triglyceride


  One molecule of glycerol

  Three fatty acids
• Phospholipids


  Fat like substance where one of the fatty acids is replaced by a phosphate (found in cell membrane)
• Sources of lipids


  Butter, cod liver oil, cream, fat on meat, olives
• Structural role lipids


  Stores energy twice as much energy than carbohydrate

  Heat insulation

  Protection of organs

  Cell membranes

  
• Metabolic role lipids


  Broken Down in respiration to release energy

  Energy is used to carry out other metabolic reactions
• Proteins


  Carbon hydrogen nitrogen sulphur phosphorus
• Structure of protein


  20 amino acids

  Peptide : Bond between acids

  Less than 20 amino acids

  Polypeptide: less than 200 amino acids

  Protein: more than 200 amino acids
• Fibrous proteins


  Little or no folding

  Form long fibres

  Strong and tough

  Keratin in nails myosin in muscles
• Globular proteins


  Lots of folding

  Form rounded shapes

  Enzymes anti bodies hormones
• Sources of protein


  Meat, fish, eggs, nuts, peas
• Structural role protein


  Fibrous proteins eg keratin in nails
• Metabolic role protein


  Used as enzymes to control metabolic reactions

  Anti bodies are used to fight infections

  Hormones are used to regulate body reactions
• Vitamins


  Carbon based

  Needed only in tiny amounts

  Body cannot make
• Water soluble vitamin


  Vitamin C

  Ascorbic acid

  Soluble in water
• Sources of vit C


  Veg fresh fruit eg oranges
• Metabolic role of vit C


  Formation of connecting tissue eg skin gums

  Growth and maintenance of bones and teeth

  Immune system

  Help wounds heal
• Deficiency of vit C


  Scurvy

  Bleeding gums

  Loose teeth

  Poor healing of skin
• Fat soluble vitamin


  Vit D

  Most common = vit D2 (calciferol)
• Sources of Vit D

  Liver milk egg yolk fish oil sunlight