Description
1. What are the main types of lipids?
3. How are triglycerides made?
Explanation & Answer
1. Phospholipids
Phospholipids consist of two fatty acid chains, a phosphate group and a glycerol group. Phospholipids are characterized by their hydrophobic--not soluble on water--tails, formed by the fatty acid chains and hydrophilic--soluble in water--heads. This makes them ideal for being the main molecule found in cellular membranes.
Glycolipids
Glycolipids are lipid molecules that contain a sugar unit, such as glucose or galactose.
Cholesterol
Cholesterol is a lipid
that consists of four hydrocarbon rings attached to a hydroxyl--hydrogen bound
to oxygen--group. The four-ring structure makes cholesterol a steroid, and the
hydroxyl group provides it with the amphipathic property of being both
hydrophilic and hydrophobic.
Many cell types and organs have the ability to synthesise triacylglycerols.
Within all cell types, even those of the brain, triacylglycerols are stored as
cytoplasmic 'lipid droplets' enclosed by a
monolayer of phospholipids and hydrophobic proteins.
In chemical terms, triacylglycerols consist of the trihydric alcohol glycerol esterified, almost invariably, with long-chain fatty acids. When the two primary hydroxyl groups are esterified with different fatty acids, the resulting triacylglycerol is made.
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