Cell Membrane Functions Protects and supports the cell Regulates the transport of materials in & out of the cell

Location: Surrounds the cell and organelles

Cell Membrane Structure Lipid Bilayer: a double layer sheet of phospholipids that makes up the cell membrane. “Water-loving” “Water-fearing” OUTSIDE INSIDE

Phospholipid: Structure Phosphate Head Lipid Tail Hydrophilic: LOVES water Hydrophobic: HATES water

Phospholipid bilayer Membrane is made up of two layers of phospholipids. WATER Hydrophilic: LOVES water Hydrophobic: HATES water

The Fluid Mosaic Model The cell membrane is made of many different parts that freely move.

Function of Phospholipids Controls what comes in and out of cells; the gatekeeper

Cholesterol Location: Found in between the phospholipids in the bilayer. Function: Keeps the membrane together; the phosphate heads are not attached to each other

Selectively Permeable Some substances can pass through the cell membrane But others can’t. Permea- means “porous” or “pass through” Yeah! I made it! Help! I can’t fit!

Proteins Location: Within the phospholipid bilayer

AP Biology Membrane Proteins  Membrane proteins:  peripheral proteins  loosely bound to surface of membrane  cell surface identity marker (antigens)  used for cellular communication  integral proteins  penetrate lipid bilayer, usually across whole membrane  transport proteins  channels, permeases (pumps)

Transport Proteins Helps larger substances pass through the bilayer

Carbohydrate Location: On the top of proteins or phospholipids Function: Help recognized similar cells to form tissues OR to recognize foreign substances in the cell

Passive Transport Movement of substances into/out of cell without using energy. HIGH  LOW concentration 3 types: 1. Simple Diffusion 2. Faciliated Diffusion 3. Osmosis HIGH LOW Weeee!!!

Simple Diffusion Molecules move from HIGH to LOW concentration (concentration gradient) Until balanced or equal- “at equilibrium”

Diffusion HIGH  LOW ( concentration gradient ) At Equilibrium Molecules still move around But…No NET flow

Facilitated Diffusion Some molecules can’t diffuse through the membrane and require special protein channels to move through. Ex. Ions, glucose HIGH LOW

Osmosis Diffusion of water through special channels called aquaporins. Moves from HIGH to LOW concentration.

Solvent + Solute = Solution Solvent: does the dissolving, like water Solute: substance that gets dissolved in the solvent

How Osmosis Works Isotonic “same or equal” EQUAL amounts of Solute in/out of cell. Hypertonic “above or higher” HIGHER solute outside Hypotonic “below or lower” LOWERsolute outside.

Isotonic “sameorequal” Hypertonic “aboveorhigher” Hypotonic “below or lower” Water in/out. Cell stays the same. Water out. Cell shrinks. Water in. Cell swells. How Osmosis Works

Iso, Hypo or Hyper? 10% NaCL 90% H 2 O ENVIRONMENT CELL 10% NaCL 90% H 2 O ISOTONIC

Water goes? 10% NaCL 90% H 2 O CELL 10% NaCL 90% H 2 O IN/OUT

Iso, Hypo or Hyper? 10% NaCL 90% H 2 O ENVIRONMENT CELL 20% NaCL 80% H 2 O HYPOTONIC

Water goes? 10% NaCL 90% H 2 O ENVIRONMENT CELL 20% NaCL 80% H 2 O IN

Iso, Hypo or Hyper? 10% NaCL 90% H 2 O ENVIRONMENT CELL 5% NaCL 95% H 2 O HYPERTONIC

Water goes? 10% NaCL 90% H 2 O ENVIRONMENT CELL 5% NaCL 95% H 2 O OUT