2c: Biological molecules

3 molecules in living organisms

- carbohydrate
- proteins
- lipids

chemical elements of carbohydrates

carbon, hydrogen, and oxygen (CHO)

chemical elements of proteins

carbon, hydrogen, oxygen, nitrogen (CHON)
(sometimes nitrogen and phosphorus)

chemical elements of lipids

carbon, hydrogen, oxygen (CHO)

structure of carbohydrates

polymers that break down into simple sugars

structure of protein

polymers that break down into their monomers: amino acids

structure of lipids

large polymers that break down into 3 fatty acid molecules and a glycerol molecule

enzymes

biological catalysts, usually proteins whose shape is vital to their function.

biological catalysts

substances that speed up a reaction without being changed itself

structure of enzyme

each enzyme has its own uniquely shaped active site and substrate

lock and key hypothesis

shape of substrate complements active site so the bound reacts and products are released from enzyme surface

factors affecting enzyme activity

temperature and pH

temperature

- optimum temperature (37 degrees C)
- rate of reaction increases with an increase in temperature up to optimum
- above optimum, rate of reaction decreases and eventually stops
- enzyme becomes denature above optimum

denatured enzyme

- when the temperature is too hot, the bonds in the structure break.
- changed shape of active site and substrate can no longer fit in
- enzyme no longer works

pH

- optimum pH (7)
- too high or low pH will affect the amino acids that make up the protein
- this changes the shape the active site and denatures the enzyme

monosaccharide

simple sugar molecule
e.g. glucose, fructose

glucose

glucose molecules contain lots of energy which can be released in respiration by breaking the bonds between the carbon atoms

disaccharide

made when 2 monosaccharides join together
e.g. maltose, sucrose

maltose

2 glucose molecules

sucrose

1 glucose and 1 fructose molecule

polysaccharide

formed from many monosaccharides
e.g. starch, glycogen, cellulose

polysaccharide formation

insoluble and useful as storage molecules

triglyceride

a lipid made of three fatty acid molecules and one glycerol molecule