Biological molecules

Biological molecules

1. Carbohydrates

2. Lipids

   • Can exist as fats, oils and waxes
   • Made up of C,H and O
   • Vast majority are Triglycerides
     • roles of triglycerides
       • Energy reserves
       • electrical insulation eg. myelin in nerve cells
       • Thermal insulation eg.blubber
       • Metabolic source of water eg. in camels
       • waterproofing eg. the waxy cuticle in plant leaves
     • structure of triglycerides
       • Three fatty acid molecules combine with one glycerol molecule
         • fatty acids have a Carboxyl group(COOH)
     • Triglycerides are bad conductors and have no charge
     • Cholesterol-is also a lipid but is not a triglyceride
       • Made up of 4 carbon rings
       • Found in cell membranes
         • It's hydrophobic nature allows it to sit between the Phospholipid tails within the cell membrane
           • So it can work to regulate fluidity and strength of the membrane

3. Water

   • structure
     • One oxygen atom covalently bonded to two hydrogen atoms
     • oxygen atoms have slight negative charge and hydrogen atoms have slight positive charge, therefore water is a polar molecule
       • other polar molecules( e.g. salts,glucose, amino acids) will disolve in water, but non-polar molecules are insoluble in water.
   • Roles
     • Plays an important role in the blood, lymphatic,excretory and digestive systems, as it is very good at transportation due to being a solvent
   • properties
     • Thermal properties
       • High specific heat capacity-means aquatic species are more able to adapt to a stable environment
         • This means lots of heat is needed to make water evaporate from the body, so sweating is very effective at cooling us down
     • Density and freezing properties
       • solid from less dense than liquid form (so large bodies of water don't often freeze )
       • High density is also used for support and protection e.g. Amniotic fluid in the womb
     • cohesion and surface tension
       • Cohesion occurs because hydrogen bonds pull water molecules in at the surface
         • Cohesion is responsible for surface tension-allowing small organisms to walk on water

4. Proteins

   • Structure
     • long chains of amino acids
       • central Carbon atom attached to four groups
         • Amino group-NH
           • Amnio groups are basic-alkaline in water
         • Hydrogen atom-H
         • R group-varies between amino acids
         • Carboxyl group- COOH
           • Carboxyl groups are acidic
             • Anything with alkaline and acidic regions is amphoteric, meaning it can resist tendency to change its PH, therefore amino acids are amphoteric
       • There are 20 amino acids, all of which plants produce, however animals only produce 12 and so they need to consume the other 8
     • Two bonded amino acids=dipeptides Multiple bonded amnio acids=polypeptiedes.
     • amino acids are held together by polypeptide bonds

5. Nucleic Acids

6. Enzymes