BIO* - Biology BIO* M121 Chapter Notes - Chapter 2: Hydrophile, Amphiphile, Glycerol

• School: CCC
• Department: BIO* - Biology
• Course: BIO* - Biology BIO* M121
• Professor: Swider

Document Summary

Steroids are a family of polycyclic hydrocarbons characterized by a bulky, four ring structure. Different isoprenoid chains can be attached to the hydrophobic rings. Steroids are necessary for proper plasma membrane structure (cholesterol), and are crucial in various signaling processes (e. g. some hormones) They consist of two lipid chains linked to glycerol, which is linked to a phosphate group, which is linked to small hydrophilic group. They are amphipathic and have both hydrophilic and hydrophobic components. Lipids can spontaneously form micelles and bilayers in solution. The hydrophilic heads face out, and the hydrophilic tails aggregate in. Lipid bilayers are the foundation plasma membranes. These are more stable than independent phospholipids in solution. Phospholipids are the foundation of cell membranes. Phospholipid bilayers provide basic plasma membrane structure. Some substances can cross more easily than others. Small, nonpolar molecules can move across the bilayer quickly. Polar molecules and ions cannot cross easily, if at all.