Y1S2 004 I Biochem Lipids Definition, Types, and Functions

Fatty Acids

• Saturated fatty acids have no double bonds and carry the maximum possible number of hydrogen atoms, example: Stearic Acid.
• Unsaturated fatty acids lack hydrogen atoms and have at least one double bond, example: Linoleic Acid.
• Cis fatty acids have hydrogen atoms on the same side of the double bond.
• Trans fatty acids have hydrogen atoms on opposite sides of the double bond.
• Essential fatty acids are derived from the diet and are necessary for vital functions, examples: Linoleic (C18:2 ω6) and α-Linolenic (C18:3 ω3).
• Non-essential fatty acids are produced by the body.

Triglycerides

• A triglyceride is formed from a molecule of glycerol and three fatty acids.
• Triglycerides are major components of very low density lipoprotein (VLDL) and chylomicrons.
• Triglycerides are important in metabolism as energy sources and transporters of dietary fat.

Phospholipids

• Phospholipids contain one or more fatty acids attached to a phosphate and an alcohol.
• Phospholipids can be attached to glycerol or sphingosine.
• Phospholipids derived from glycerol are called phosphoglycerides, example: Cardiolipin.
• Phospholipids derived from sphingosine are called Sphingomyelin, found in the brain.

Glycolipids

• Glycolipids are sugar-containing lipids derived from sphingosine.
• The simplest glycolipid is a cerebroside, containing a sugar residue of glucose or galactose, found in neural tissue.

Sterol Lipids

• Cholesterol is built from 4 linked hydrocarbon rings with a hydrocarbon tail and a hydroxyl group.
• In membranes, cholesterol's hydroxyl group interacts with nearby phospholipid head groups.
• Bile salt originates from cholesterol and has the 4 linked hydrocarbon rings plus taurine or glycine or both.

Lipid Profile

• High density lipoprotein cholesterol (HDL-C) is >1.2 mmol/L.
• Low density lipoprotein cholesterol (LDL-C) is 2.4 mmol/L.
• Triglyceride (TG) levels are important in lipid profiles.

Lipids Definition and Functions

• Lipids are a chemically diverse group of organic compounds defined by their insolubility in water.
• Lipids are highly soluble in non-polar solvents like chloroform and ether.
• Lipids' water-insolubility contributes to the complexity in their digestion, transport, and metabolism.
• Lipids are essential to the overall energy economy of the cell.

Test your knowledge on the structures, types, and functions of lipids, including their role in gaseous exchange and diseases associated with lipid storage. This quiz covers the basics of lipids and their importance in biology.