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

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biochemistry

BIOCHEMISTRY

© 2007 Paul Billiet ODWS

carbon
CARBON
  • Tetravalent  4 different bonds  variety  isomerism
  • Forms long chains (polymers)  macromolecules and ring structures
  • Tetrahedral structure  3-D variation  optical isomerism

© 2007 Paul Billiet ODWS

organic compounds
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
  • 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

carbohydrates ch 2 o n
Organization:Monosaccharides, Disaccharides, Polysaccharides

Monosaccharides

5C pentoses (eg ribose, deoxyribose)

6C hexoses (eg glucose, fructose, galactose)

OH

C

H

H

H

RIBOSE

C

C

GLUCOSE

OH

OH

CH2OH

C

H

O

H

C

OH

CH2OH

OH

O

C

C

H

H

H

H

C

C

OH

OH

CARBOHYDRATES (CH2O)n

© 2007 Paul Billiet ODWS

glycoside linkage to form disaccharides

OH

OH

C

C

O

O

H

H

H

H

H

H

C

C

C

C

OH

OH

OH

OH

CH2OH

CH2OH

C

C

H

H

H

H

C

C

OH

OH

Glycoside linkage to form disaccharides

The two sugars are joined by condensation and may be broken by hydrolysis

© 2007 Paul Billiet ODWS

slide6

OH

OH

H

O

H

O

C

C

C

C

O

H

H

H

H

H

C

C

C

OH

OH

OH

CH2OH

CH2OH

C

C

H

H

H

C

OH

A disaccharide

+ H2O

© 2007 Paul Billiet ODWS

different monosaccharides can be used
Different monosaccharides can be used
  • sucrose = glucose + fructose
  • lactose = glucose + galactose
  • maltose = glucose + glucose

© 2007 Paul Billiet ODWS

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

Polysaccharides

Unbranched polysaccharides

  • Cellulose in plant cell walls

© 2007 Paul Billiet ODWS

carbohydrate functions
CARBOHYDRATEFUNCTIONS

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

carbohydrate functions1
CARBOHYDRATE FUNCTIONS
  • Polysaccharides Large molecules insoluble in water:
  • Osmotically inactive carbohydrate storage, (seeds, roots, chloroplasts);
  • Structural (cellulose in plants)

© 2007 Paul Billiet ODWS

lipids c h o
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

fatty acids carboxylic acid long hydrocarbon chain

Carboxylic acid

O

C

CH3

OH

Hydrocarbon chain

O

C

CH3

OH

Fatty acids: carboxylic acid + long hydrocarbon chain

A saturated fatty acid

An unsaturated fatty acid

© 2007 Paul Billiet ODWS

fats and oils

HO - CH2

O

HO - CH

C

CH3

OH

HO – CH2

O

C

CH3

OH

Fats and Oils

fatty acids + glycerol (1, 2 or 3 = mono , di or triglycerides)

Condensation reactions

© 2007 Paul Billiet ODWS

two fatty acids joining glycerol a diglyceride

O - CH3

O - CH

O

C

CH3

HO - CH3

O

C

CH3

Two fatty acids joining glycerol = A diglyceride

+2H20

© 2007 Paul Billiet ODWS

phospholipids
Phospholipids
  • in lipoprotein membranes (plasma, nuclear, mitochondrial etc.)

© 2007 Paul Billiet ODWS

other lipids
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

lipid functions in genera l
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

amino acids proteins c h o n s
AMINO ACIDS&PROTEINS: C, H, O, N, S

cysteine

arginine

methionine

phenylalaline

aspartic acid

© 2007 Paul Billiet ODWS

amino acids

R

H2N-C-COOH

H

Amino acids
  • amino group, carboxyl group, hydrogen and a variable side group (residue) each joined to a central carbon atom

© 2007 Paul Billiet ODWS

types of amino acids
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

functions of amino acids
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

the peptide bond
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

slide24

R

R

O

O

H

H

N C C-OH

N C C-OH

R

O

H

H

H

+ H2O

N C C-OH

H

H

H

R

O

H

N C C

H

H

Condensation reaction

A dipeptide is formed

The peptide bond

© 2007 Paul Billiet ODWS