 BIG biological molecules ◦ Made of smaller parts  Monomers  Carbon-based (organic) ◦ Carbohydrates ◦ Nucleic acids ◦ Proteins ◦ Lipids

 Structure: ◦ Glycerol head ◦ Fatty acid tail  Used for: ◦ Long term energy storage ◦ Insulation ◦ Major component of cell membranes ◦ Signaling molecules and hormones  Examples: ◦ Fats, oils, waxes  Found in: ◦ All the good tasting foods

 ALL cells have cell membranes for support and protection  All cells need to import and export molecules in order to function properly and maintain homeostasis

1. Regulates passage of nutrients, wastes, gases, and water into and out of cell *Selectively permeable – “picky” about what passes 2. Separates the cell from the environment 3. Allows cells to communicate with other cells via receptors on the surface

 Made of a phospholipid bilayer ◦ Phosphate (hydrophilic) “head” ◦ Lipid (hydrophobic) “tail” Phospholipid bilayer

 Protein channels ◦ Allow large molecules to pass through Protein channels

 SOME SUBSTANCES, ARE SMALL ENOUGH TO MOVE THROUGH THE SPACES BETWEEN THE LIPIDS.  NAME 3 EXAMPLES.

 Receptor Protein (Carbohydrate Antennae) ◦ Receives messages from outside the cell ◦ Cell communication is key for homeostasis! Receptor Protein