4.4 LIPIDS

Lipids

• Consist of C,H and O• High hydrogen to

oxygen ratio• Non polar

hydrophobic compounds

LIPIDSLIPIDS

FatsFats OilsOils

WaxesWaxes

PhospholipidsPhospholipids

SteroidsSteroids

• Fats & Oils are similar chemically• At room temperature, fats are solid and oils are liquid

Triglycerides (fats & oils)

•composed of a glycerol plus three fatty acids•“true” fats

FUNCTIONS •Serve as a good energy store•Stored under skin as insulator•Transport fat soluble vitamins

Phospholipids

•Composed of a diglyceride that bonded to phosphate group

FUNCTIONS •Most abundant lipids in plasma membrane

•Control cell permeability

Waxes

Insoluble

FUNCTIONS •Form a waterproof layer of cuticle on:

•Epidermis of plants•Exoskeleton of insects

•Feathers of bird•Fur of mammals

Steroids

CholesterolCholesterol

Makes the plasma membrane more rigid &

stable

Makes the plasma membrane more rigid &

stable

Sex hormones (testosterone,

oestrogen, progesterone)

Sex hormones (testosterone,

oestrogen, progesterone)

Control sexual development & body physiology

Control sexual development & body physiology

BileBile

Emulsifies fatsEmulsifies fats

Components of FatsComponents of Fats

GlycerolGlycerol Fatty AcidFatty Acid

• Colorless, odorless, sweet –tasting syrupy liquid

• 3 carbon and 3 hydroxyl group (OH)

• Colorless, odorless, sweet –tasting syrupy liquid

• 3 carbon and 3 hydroxyl group (OH)

• Organic acid• Molecular structure

• Long hydrocarbon tail with carboxyl (-COOH) at one end

• Different fatty acids have different hydrocarbon tails

• Organic acid• Molecular structure

• Long hydrocarbon tail with carboxyl (-COOH) at one end

• Different fatty acids have different hydrocarbon tails

Glycerol

Fatty Acid

Formation & breakdown of fats & oils

Source of Fats

Saturated fats vs unsaturated fats

Solid state at room temperature

Are in the liquid state (oil) at room temperature

Differences between saturated and unsaturated fats

Saturated fats Aspects that are different

Unsaturated fats

All covalent bonds between carbon atoms are single (C-C)

Type of chemical bond Existence of double covalent bonds between carbon atom (C=C)

Less reactive Reactivity More reactive because due to the double bonds

More tightly packed together

Packaging of the fat molecule

Less tightly packed due to the double bonds

Solid (fat) State of matter at room temperature

Liquid (oil)

Mainly from animal products: red meat, chicken skin, butter & coconut oil)

Source Mainly from plants: vegetable oils, palm oil, corn oil and olive oil

Increase level of “bad” cholesterol

Effects on blood cholesterol level

Increase levels of “good” cholesterol