lipids and lipoproteins

what are lipids

organic molecules composed of carbon hydrogen and oxygen

functions of lipids

energy storage - lipids are highly efficient energy

cell membranes -form structural basic cell membranes creating a barrier

thermoregulation - lipids provide thermal insulation to regulate body heat

synthesis of important biological molecules

classification of lipids

fatty acids

Triacylglycerols (triglycerides)

Glycerophospholipids

Sphingolipids

Steroids

structure of fatty acid

long hydrocarbon chain referred tail

Carboxyl group COOH referred to as the head

types of fatty acids

saturated - contain no Carbon to Carbon double bonds Palmitic acid.

Unsaturated - Contain one or more carbon to carbon double bonds (C=C) Oleic acid.

Monounsaturated - have one C=C double bond

Polyunsaturated - have multiple C=C double bonds

isomerism in fatty acids

cis configuration - bend of around 30 degrees in hydrocarbon chain

trans configuration - result in a straight chain

how to number fatty acids

• Delta (ΔΔ) Numbering: Starts from the carboxyl (COOHCOOH) end.

• Omega (ωω) Numbering: Starts from the methyl (CH3CH3​) end.

Triacylglycerols (Triglycerides) structure and function

structure - one molecule of glycerol, 3 molecules of fatty acids

function - energy reservoirs, high energy yield

Glycerophospholipids

structure

a glycerol backbone ]

two fatty acid tails

A phosphate group

An additional polar alcohol group

sphingolipids structure

ceramide is formed when a fatty acid is attached to sphingosine

steroids structure and function

structure - do not contain fatty acids, has 4 fused carbon rings

function:

hormone signalling - many steroids function as hormones

cholesterol - plays a role in membrane fluidity

what are lipoproteins

what is their structure

complex molecules responsible for the transport of lipids through the bloodstream

Non - polar Core: Contains hydrophobic lipids

Amphiphilic Surface - attracts and repels water

Function of Lipoproteins

transport vehicles - they act as transport vehicles for triglycerides and cholesterol

• Classifications: Lipoproteins are classified into five broad categories based on their density, size, and lipid composition:

  • Chylomicrons

  • Very-low-density lipoproteins (VLDL)

  • Intermediate-density lipoproteins (IDL)

  • Low-density lipoproteins (LDL)

  • High-density lipoproteins (HDL)

HDL - transports endogenous cholesterol (cholesterol body makes on its own) from tissues to liver

VLDL,IDL,LDL - transports endogenous cholesterol from liver to tissues

lipoprotein, chylomicrons (exogenous pathway)

carry fat from liver into tissues

LPL breaks down triglycerides so tissues can use or store fat

remmnants go to the liver

endogenous pathway

VLDL - carries fat from liver to tissues

IDL - forms after VLDL loses some fat

LDL - carries cholesterol to body cells

HDL - reverse cholesterol transport

collects excess cholesterol from tissues

takes it back to the liver to be removed