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4 .3 PRO TEINS

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Elements in protein

Carb on, hyd rog en, oxy gen, nitrog en, sulphur &phosphorus

Basic unit: amino acids

Amino a cids a re joined to ea ch other in a p a rticula rseq uence to f orm poly p ep tide cha in or p rotein

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Forma tion and b rea kdown of

d ipeptides & polypeptides

+

condensation

hydrolysis

Peptide bond

+ H2O

Amino

acid

Amino

aciddipept ide

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+

condensation

hydrolysis

++ 2H2O

Aminoacid

Aminoacid

Aminoacid tripeptide

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condensation

hydrolysisA polypeptide chain

+ 9H2O

* 10 to 100 amino acids

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Protein Structures

Comp lete p rotein molecule is a simp le unb ra nchedcha in of amino a cids

3D protein structure is classified into 4 levels:

1. Primary structure

2. Secondary structure

3. Tertiary structure

4. Q ua ternary structure

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keratin silk

Enzymes, hormones, antibodies, haemoglobin

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Essentia l amino a cid s & Non essentia lamino acids

Essential:

Amino acid that required for protein synthesis, butcannot be synthesized in the human body

O btained f rom f ood we eat

Non essential:

Amino acid that is required for protein synthesis andcan be synthesized by humans

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LIPIDS

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LIPIDS

Consist of C,H and O

High hyd rog en to oxy gen ra tio

Non pola r hyd rop hob ic compounds Includ e FATS, O ILS, W AXES, PHO SPHO LIPIDS and

STERO IDS

Fats and oils similar chemically

At room tempera ture, fa ts a re solid a nd oils a reliquid

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Lipids Function

Trig lycerid es (fa ts & oils)

composed of a glycerol plus threefatty acids t rue fa ts

Serve a s a good energ y store

Stored under skin as insulatorTra nsport f at soluble vitamins

Phospholipids:Composed of a digly ceride that

bonded to p hospha te group

Most a bundant lip ids in p lasma

membrane

Control cell p ermeab ility

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Lipids Function

W a x e s Insoluble

Form a waterproof layer of cuticle on:

1 .Ep ider mis of p lants

2 .Exoskele ton of insects3 .Fea thers of b ird4.Fur of mammals

Steroidsa)Cholesterol

b)Sex hormones (testosterone, oestrogen,

progesterone)

c)Bile

Ma kes the p lasma membra ne more rig id& stab le

Control sexual development & body

physiology

Emulsifies fats

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Components of f a ts & oils

2 d if f erent kinds of org a nic molecules tha t join toma ke fa ts & oils a re:

Glycerol

Fatty acid

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Glycerol

Color less, odor less,sweet tasting sy rupyliquid

3 ca rbon and 3hyd roxy l g roup (O H)

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Fa tty acid

O rg anic acid

Molecular structure

Long hyd rocarb on ta ilwith carboxyl (-CO O H) a t one end

Diff erent f a tty acidshave dif f erent

hyd roca rbon tails

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Forma tion & b rea kdown of f a ts & oils

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Saturated fats vs unsaturated fats

Solid state at room tempera ture

Are in the liquid state (oil) at

room temperature

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Differences between saturated and unsaturated fats

Saturated fats Aspects that are different Unsaturated fats

All covalent b onds betweencarbon atoms are single

(C-C)

Type of chemical bond Ex istence of doublecovalent bonds betw een

car bon atom (C= C)Less reactive Reactivity Mor e rea ctive b ecause d ue

to the double bonds

More tig htly p ackedtogether

Packaging of the f atmolecule

Less tig htly p acked due tothe double bonds

Solid (fat) State of matter a t room

temperatureLiquid (oil)

Ma inly f rom animalproducts: red meat, chicken

skin, butter & coconut oil)

Source Mainly from plants:vegeta b le oils, pa lm oil,

corn oil and olive oil

Increase level of bad

cholesterol

Effects on blood cholesterol

level

Increa se levels of good

cholesterol