Editing Biochemical Macromolecules (section)

== 3. Lipids: Membranes and Storage ==

Unlike the other three macromolecules, lipids are not defined by a specific monomer-polymer structure. Instead, they are grouped together because they are entirely or largely hydrophobic (water-repelling), consisting mainly of hydrocarbon chains.

* '''Key Components:''' Fatty acids (long hydrocarbon chains like CH2 or CH3 repeats) and glycerol.
* '''Types and Functions:'''
** ''Triglycerides (Fats and Oils):'' Used for long-term energy storage, insulation, and cushioning. They consist of a glycerol backbone attached to three fatty acid tails.
** ''Phospholipids:'' The fundamental building blocks of all cellular membranes. They are amphipathic, meaning they have a hydrophilic (water-loving) phosphate head and two hydrophobic fatty acid tails. In water, they spontaneously arrange into a bilayer.
** ''Steroids:'' Characterized by a carbon skeleton consisting of four fused rings. Cholesterol is a vital structural component of animal cell membranes and serves as the precursor for steroid hormones (like testosterone and estrogen).