© 2007 Paul Billiet
ODWS

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Tetravalent
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4 different bonds
 variety
 isomerism
Forms long chains (polymers)
 macromolecules and ring structures
Tetrahedral structure
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3-D variation
 optical isomerism
© 2007 Paul Billiet
ODWS

 Compounds containing carbon found in living organisms
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Not including carbonates, hydrogen carbonates,
CO
2 or CO
Often based upon a skeleton of carbon
 An infinite variety possible
 Evolution has chosen a few for use in living organisms
 There are four principal groups: sugars, fatty acids, amino acids and nucleotides
© 2007 Paul Billiet
ODWS

2
n
Organization: Monosaccharides,
Disaccharides, Polysaccharides
Monosaccharides
 5C pentoses (eg ribose , deoxyribose )
 6C hexoses (eg glucose, fructose, galactose )
GLUCOSE
CH
2
OH
OH
CH
2
OH
O
C
H
C O H
C
H
H H
H
C
H
OH
H
C
OH
C C
RIBOSE
OH
C C
OH
© 2007 Paul Billiet
ODWS
OH
H OH

The two sugars are joined by condensation and may be broken by hydrolysis
H
C
OH
C
H
CH
2
OH
C
H
OH
O H
H
H
C
OH
C
C
OH OH
C
H
CH
2
OH
C
H
OH
O H
H
C
OH
C
OH
© 2007 Paul Billiet
ODWS

H
C
OH
C
H
CH
2
OH
C
H
OH
O H H
H
C
OH
C
O
C
C
H
CH
2
OH
C
H
OH
O H
H
C
OH
C
OH
+ H
2
O
© 2007 Paul Billiet
ODWS

 sucrose = glucose + fructose
 lactose = glucose + galactose
 maltose = glucose + glucose
© 2007 Paul Billiet
ODWS

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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

Sugars (mono and disaccharides) small molecules soluble in water :
 Maintenance of osmotic balance (e.g. salts in blood plasma, plant cell turgidity);
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 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

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

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

A saturated fatty acid
Carboxylic acid
O
CH
3
Hydrocarbon chain
C
OH
An unsaturated fatty acid
CH
3
C
O
OH
© 2007 Paul Billiet
ODWS

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

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

Two fatty acids joining glycerol
= A diglyceride
O
CH
3
C
O
O - CH
3
+
CH
3
C
O - CH
2H
2
0
HO - CH
3
© 2007 Paul Billiet
ODWS

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

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

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 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

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

 amino group , carboxyl group , hydrogen and a variable side group
(residue) each joined to a central carbon atom
R
H
2
N -CCOOH
H
© 2007 Paul Billiet
ODWS

 Amino end and carboxyl end can be ionised NH 3+ 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

 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

 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

R O
H
N C C-OH
H
H
Condensation reaction
R O
H
N C C-OH
H
H
A dipeptide is formed
R O
H
N C C
H
H
H R O
N C C OH
H
The peptide bond
+ H
2
O
© 2007 Paul Billiet
ODWS