Food

• Why do we need food?

  • Energy
  • Growth and repair of all cells
  • To provide raw materials for the processes of metabolism and continuity
• Six Common Elements

  • Carbon (C)
  • Hydrogen (H)
  • Oxygen (O)
  • Nitrogen (N)
  • Phosphorus (P)
  • Sulphur (S)
• Elements in Salts

  • Sodium (Na)
  • Magnesium (Mg)
  • Chlorine (Cl)
  • Potassium (K)
  • Calcium (Ca)
• Trace Elements

  • Iron (Fe)
  • Copper (Cu)
  • Zinc (Zn)
• Trace Element

  An element that is needed in small amounts.
• Biomolecule

  A chemical substance made in the cells of a living organism.

  Examples of biomolecules include: 

  • Carbohydrates
  • Proteins
  • Lipids
  • Vitamins
  • Nucleic acid - DNA and RNA
• Elements in Carbohydrates

  • Carbon (C)
  • Hydrogen (H)
  • Oxygen (O)
• Monosaccharides 

  Monosaccharides are single sugar molecules.
• Three common monosaccharide sugars are:

  • Glucose
  • Fructose
  • Galactose

  Sources of Monoscaccharides

  • Fruits
  • Honey
• Disaccharides 

  Disaccharides are a carbohydrate consisting of two monosaccharides joined together.

  • A double sugar molecule
  • Soluble in water
  • Sweet tasting 
• Examples of Disaccharides

  • Lactose - Formed by the monosaccharides glucose and galactose.
  • Maltose - Formed by two glucose monosaccharides.
  • Sucrose - Formed by glucose and fructose.

  Sources of Disaccharides

  • Table sugar 
  • Milk
  • Spelt bread

  Formula of Disaccharides

  All disaccharides have the chemical formula C12H22O11.
• Polysaccharides 

  Polysaccharides are many monosaccharide molecules joined together.

  • Not soluble in water
  • Not sweet tasting 
• Examples of Polysaccharides

  • Starch
  • Glycogen
  • Cellulose
  • Chitin

  Sources of Polysaccharides

  • Bread 
  • Pasta
  • Rice
• What are lipids?

  • Fats (solid at room temperature)
  • Oils (liquid at room temperature)
  • Steroids (cholesterol, oestrogen, and progesterone)
  • Waxes (cover insect bodies and help repel water)
• Sources of lipids

  • Fat in meat
  • Avocado
  • Butter
  • Nut butters 
• Elements in Lipids

  Lipids are composed of carbon, hydrogen and oxygen.

  Unlike carbohydrates there is no ratio between any of the elements.
• Types of Lipids: Triglycerides

  A triglyceride is the smallest sub-unit of a lipid and they are composed of:

  • One glycerol molecule
  • Three fatty acid molecules
• Types of Lipids: Phospholipids

  Phospholipids are part of cell membranes and are composed of:

  • One glycerol molecule
  • Two fatty acid molecules
  • One phosphate group
• Vitamins

  Vitamins are biomolecules that are essential organic catalysts of metabolism. 
• Fat Soluble Vitamins

  • A
  • D
  • E
  • K

  Water soluble Vitamins

  • B
  • C
• Vitamin C (Ascorbic Acid)

  • Vitamin C helps build connective tissues such as skin, blood vessels, ligaments, and tendons.
  • Dietary source: citrus fruit, green veg
  • Disease: scurvy - soft bleeding gums, loose teeth
• Vitamin D (Calciferol)

  • Helps absorb calcium in the gut which keeps our bones and teeth healthy.
  • Source: dairy, egg yolk, fish oil, sunlight
  • Disease: rickets/osteomalacia - bones lose calcium and become weak
• Elements in Protein

  Proteins contain the elements carbon, hydrogen, oxygen, and nitrogen.

  Proteins can also contain sulfur, iron, and phosphorus. 
• Sources of Protein

  • Lean meat
  • Fish 
  • Soya
  • Eggs
  • Pulses
• Structure of Protein - Amino Acids

  • Proteins are composed of a long chain of amino acids.  
  • We say amino acids are the 'building blocks' of proteins.
  • There are 20 common amino acids.
  • Amino acids are joined to each other via peptide bonds.  
  • Many amino acids bonded together results in a polypeptide chain.
• Amino Acid Structure

  Each amino acid contains four distinct chemical groups bonded to a central carbon atom:

  • An amino group (NH2)
  • A carboxyl group (COOH)
  • A side chain (R group)
  • A single hydrogen atom 
• Structural Role of Biomolecules

  The structural role of biomolecules is the function or job of carbohydrates, lipids and proteins in making various parts of an organism.
• Structural Carbohydrates

  Carbohydrates, in the form of polysaccharides, play a very important role in the cell structure of organisms, especially those without bones, as they give cells strength.

  • Cellulose: found in the cell walls of plants
  • Chitin: cell wall of fungi and exoskeleton of insects
  • Lignin: in plants with wood or bark
• Structural Proteins

  Structural proteins are usually fibrous in nature. They look like threads or ropes under a microscope.

  • Keratin: in the skin, hair, and nails.
  • Myosin and actin: found in muscles that allow contractions
  • Lipoprotein: Form the cell membrane along with phospholipids
• Structural Lipids

  Lipids provide structure to cells in a wide variety of ways such as:

  • Helping to waterproof the body.
  • Offering protection to organs such as the liver and the heart.
  • Composing the cell membrane of organisms (phospholipids and lipoproteins).
  • Phospholipids (and lipoproteins) are a major component in cell membranes.
  • Myelin is a fatty white substance that surrounds the axons of motor neurons and helps insulate electrical impulses.