1. BIOCHEMISTRY
© 2007 Paul Billiet ODWS

2. CARBON Tetravalent  4 different bonds  variety
Tetrahedral structure  3-D variation  optical isomers
© 2007 Paul Billiet ODWS

3. Carbon (Cont.)
Forms long chains (polymers)  macromolecules and ring structures

4. Organic compounds
Compounds containing carbon found in living organisms
Not including carbonates, hydrogen carbonates, CO2 or CO
Often based upon a skeleton of carbon
An infinite variety possible
There are four principal groups: sugars, fatty acids, amino acids and nucleotides
© 2007 Paul Billiet ODWS

5. CARBOHYDRATES (CH2O)n
Organization: Monosaccharides, Disaccharides, Polysaccharides
Monosaccharides
5C pentoses (eg ribose, deoxyribose)
6C hexoses (eg glucose, fructose, galactose)
GLUCOSE
CH2OH C H OH O
RIBOSE OH H
CH2OH C O
© 2007 Paul Billiet ODWS

6. Glycoside linkage to form disaccharides
The two sugars are joined by condensation and may be broken by hydrolysis
Click here for animation
CH2OH C H OH O
© 2007 Paul Billiet ODWS

7. A disaccharide
CH2OH C H OH O
+ H2O
© 2007 Paul Billiet ODWS

8. Different monosaccharides can be used
sucrose = glucose + fructose
lactose = glucose + galactose
maltose = glucose + glucose
© 2007 Paul Billiet ODWS

9. Polysaccharides Macromolecules Common ones based upon glucose
Branched polysaccharides
Amylose & amylopectin (starches) are synthesised in plants.
Glycogen is synthesised in animals, more highly branched than starches = more compact
Unbranched polysaccharides
Cellulose in plant cell walls
© 2007 Paul Billiet ODWS

10. PLANT STARCHES
Amylase
Amylopectin

11. GLYCOGEN
(Animal Starch with many branches)

12. Cellulose

13. CARBOHYDRATE FUNCTIONS
Sugars (mono and disaccharides) small molecules soluble in water:
Maintenance of osmotic balance (e.g. salts in blood plasma, plant cell turgidity);
transport of energy reserves (e.g. glucose in blood or sucrose in sap);
energy substrate (respiration and photosynthesis);
energy store (sugar cane);
flavouring (fruits); reward (nectar);
precursors (building blocks) of polysaccharides, nucleotides and amino acids
© 2007 Paul Billiet ODWS

14. CARBOHYDRATE FUNCTIONS
Polysaccharides Large molecules insoluble in water:
Osmotically inactive carbohydrate storage, (seeds, roots, chloroplasts);
Structural (cellulose in plants)
© 2007 Paul Billiet ODWS

15. LIPIDS C, H, O More hydrogen (more reduced) than carbohydrates.
Insoluble in water, soluble in organic solvents (alcohols, acetone, chloroform etc)
© 2007 Paul Billiet ODWS

16. Fatty acids: carboxylic acid + long hydrocarbon chainOH
CH3
Carboxylic acid
Hydrocarbon chain
A saturated fatty acid
An unsaturated fatty acid C O OH
CH3
© 2007 Paul Billiet ODWS

17. Unsaturated fatty acids
no double bonds
one or more double bonds
abundant in fats
abundant in oils
more reduced
less reduced
more energy
less energy
high melting point
low melting point
© 2007 Paul Billiet ODWS

18. Fats and Oils
fatty acids + glycerol (1, 2 or 3 = mono , di or triglycerides) C O OH
CH3
HO – CH2
HO - CH2
HO - CH C O OH
CH3
Condensation reactions
© 2007 Paul Billiet ODWS

19. Two fatty acids joining glycerol = A diglyceride
CH3
O - CH3
HO - CH3
O - CH
+ 2H20
© 2007 Paul Billiet ODWS

20. Phospholipids
in lipoprotein membranes (plasma, nuclear, mitochondrial etc.)
© 2007 Paul Billiet ODWS

21. Other lipids Steroids: multiple ring structures (e.g. cholesterol)
Functions: cell membrane structure, digestion (help to emulsify fats), hormones (testosterone etc), vitamins (e.g. Vitamin D), poisons
Waxes: long chain alcohol + fatty acids
Water proof coating to leaves, fur feathers, insect exoskeletons.
Used by bees to construct their honey combs.
© 2007 Paul Billiet ODWS

22. STEROIDS

23. LIPID FUNCTIONS IN GENERAL
STRUCTURAL: biological membranes (phospholipids, steroids, glycolipids), cushioning (fat deposits round the kidneys)
ELECTRICAL INSULATION: myelin sheath round axons
THERMAL INSULATION: subcutaneous fat deposits.
WATER PROOFING: waxes and oils
ENERGY STORE AND SUBSTRATE: very condensed form of energy (37 kJ g-1) used by animals and seeds.
HORMONES: steroids
VITAMINS: precursor to Vit D
BUOYANCY: oil droplets in plankton
© 2007 Paul Billiet ODWS

24. AMINO ACIDS & PROTEINS: C, H, O, N, S
arginine
cysteine
methionine
phenylalaline
aspartic acid
© 2007 Paul Billiet ODWS

25. Amino acids
amino group, carboxyl group, hydrogen and a variable side group (residue) each joined to a central carbon atom
H2N-C-COOH R H
© 2007 Paul Billiet ODWS

26. Types of amino acids
Amino end and carboxyl end can be ionised NH3+ and COO- to give acidic and basic characteristics
At pH 7 both groups are ionised.
The residues are side chains which give the individual properties to the amino acid (acidic, basic, neutral and nonpolar)
© 2007 Paul Billiet ODWS

27. Functions of amino acids
Protein synthesis, energy reserve, hormones (thyroxin)
20 different amino acids used in protein synthesis though others do occur in nature.
Essential amino acids cannot be synthesised by the organism and must form part of their diet
© 2007 Paul Billiet ODWS

28. The peptide bond
Carboxyl group + amino group form a strong covalent bond releasing water in to process water = a condensation reaction (the reverse is hydrolysis)
Amino acids join together in a long chain: N terminal end to C terminal end = a polypeptide
© 2007 Paul Billiet ODWS

29. Condensation reaction A dipeptide is formed
N C C-OH R H O
Condensation reaction
A dipeptide is formed
N C C R H O
N C C-OH
+ H2O
The peptide bond
© 2007 Paul Billiet ODWS