Lipids Classification Quiz

Lipids Classification

• Lipids are classified into three categories: Simple, Compound, and Derived.
• Simple lipids include fats and waxes.
• Compound lipids include phospholipids and glycolipids.
• Derived lipids include glycerol, cholesterol, fatty acids, bile salts, and ketone.

Simple Lipids

• Simple lipids are esters of fatty acids with alcohol.
• Fats are esters of fatty acids and glycerol.
• Waxes are esters of long-chain fatty acids and long-chain alcohols.
• Fats are further classified into simple and mixed triacylglycerols.
• Triacylglycerols provide energy in the absence of carbohydrates.
• Simple triacylglycerols have the same type of fatty acids on all three hydroxy groups.
• Mixed triacylglycerols have different fatty acids on the hydroxy groups.
• Triglycerides are stored in adipose tissue.
• High levels of triglycerides are associated with obesity, diabetes, and heart and blood vessel disease.
• Triacylglycerols are good energy sources doubling the amount of Glucose.
• Dietary fats carry fat-soluble vitamins. Vitamin A, D, E, and K dissolve in dietary fats.
• Important fatty acids, such as linoleic acid and alpha-linolenic acid (omega-3 and omega-6 fatty acids respectively), are essential.

Glycerides

• Glycerides (acylglycerols) are esters formed from glycerol and fatty acids.
• These are further classified into monoglycerides, diglycerides, and triglycerides.

Adipose Tissue

• Adipose tissue is located beneath the skin (subcutaneous fat), around internal organs (visceral fat), in bone marrow, and in muscles (intermuscular fat). It's also found in breast tissue.
• Adipose tissue plays a role in obesity and cardiovascular disease. Excessive adipose tissue accumulation results from chronic overnutrition and a lack of physical activity.

Phospholipids

• Phospholipids are esters of fatty acids with alcohol, and contain non-lipid compounds like phosphate, nitrogenous bases, or sugar.
• They are further classified into glycerophospholipids and sphingophospholipids.
• Glycerophospholipids have a glycerol backbone and two fatty acids. Phosphatidic acid is the parent compound.
• Phospholipids have both hydrophilic (polar) and hydrophobic (non-polar) components. The charged head is composed of phosphate and alcohol.
• The non-polar tails consist of fatty acids.
• Important components of cells, bile, cell membranes, signal molecules, lung components, and lipoproteins.

Specific Glycerophospholipids

• Phosphatidylserine (PS)
• Phosphatidylethanolamine (PE)
• Phosphatidylcholine (PC)
• Phosphatidylglycerol (PG)

Cardiolipin

• Cardiolipin (diphosphatidylglycerol) is formed from two molecules of phosphatidic acid (PA) and one glycerol molecule.
• Cardiolipin is found in inner mitochondrial membranes.
• It's vital for respiratory complexes in the electron transport chain (ETC).

Plasmalogens

• Plasmalogens contain an ether-linked fatty acid at carbon 1 of glycerol.
• They are abundant in nerve tissues and heart muscles.

Platelet Activating Factor (PAF)

• PAF is an ether-linked glycerol phospholipid.
• It plays a role in various physiological functions, including platelet aggregation, activation, and triggering thrombotic and inflammatory events.
• PAF causes bronchoconstriction.

Sphingolipids

• Sphingolipids have a sphingosine backbone.
• Ceramides are a parent compound for sphingophospholipids. Sphingosine + Fatty Acid = Ceramide
• They are critical for cell membranes, especially in nerve tissue

Sphingomyelins

• Formed by Ceramide + Phosphorylcholine.
• Sphingomyelins are in the myelin sheath of the nervous system, protecting and insulating neuronal fibers.

Sphingolipidoses

• Defects in enzymes that break down sphingolipids cause sphingolipidoses.
• Diagnose via specific sphingolipid accumulation, enzyme activity measurements, and histological analysis of affected tissues. Examples include Tay-Sachs, Gaucher's, Krabbe's, and Niemann-Pick Diseases.

Glycolipids

• Glycolipids are essential components of cell membranes, particularly nerve tissues, and are located in the outer leaflet of the plasma membrane. The carbohydrate portion plays a role in cell interactions.
• They’re categorized as glycosphingolipids.
• Cerebrosides contain one sugar (glucose or galactose).
• Gangliosides are acidic glycosphingolipids. They have oligosaccharides including terminal, charged N-acetylneuraminic acids (NANA).

Cerebroside Classification

• Galactocerebrosides have a galactose head group, primarily present in brain cells.
• Glucocerebrosides have a glucose head group, present in non-neuronal cells.

Ganglioside Structure

• Gangliosides are built from ceramides and branched oligosaccharides with one or more sialic acids.
• Sialic acids are 9-carbon monosaccharides and their derivatives. Gangliosides are abundant in nervous tissue.

Glycosphingolipid Degradation

• Glycosphingolipid degradation happens inside lysosomes following endocytosis of membrane material.
• Specific acid hydrolases carry out this degradation.