Types of Lipids and Where They Are Found

Examples of Lipids

Fat cells, SEM
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Lipids are a diverse group of fat-soluble biological molecules. Here is a look at different types of lipids and where they are found.

Triacylglycerols or Triglycerides

  • The largest class of lipids goes by different names: triacylglycerols, triglycerides, glycerolipids, or fats.​
  • Location: Fats are found in many places. One well-known form of fat is found in human and animal tissue.
  • Function: The primary function of fats is energy storage.
  • Example: margarine

Steroids

  • All steroids are hydrophobic molecules derived from a common 4 fused carbon ring structure.
  • Location: Cellular membrane, digestive system, endocrine system
  • Function: (1) Hormones, which enter cells and initiate specific chemical reactions (2) Part of cellular structure, adding fluidity to cellular membranes.
  • Example: The most common steroid is cholesterol. Cholesterol is a precursor for making other steroids. Other examples of steroids include bile salts, estrogen, testosterone, and cortisol.

Phospholipids

  • Phospholipids are derivatives of triglycerides that consist of a glycerol molecule with two fatty acids, a phosphate group on the third carbon, and commonly an additional polar molecule. The diglyceride portion of a phospholipid is hydrophobic, while the phosphate is hydrophilic.
  • Location: Cell membrane.
  • Function: Form basis of cellular membranes.
  • Example: Phospholipid bilayer of the cellular membrane.

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