Cell Membrane Functions Protects and supports the cell

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

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

Phospholipid bilayer Membrane is made up of two layers of phospholipids. WATER Hydrophilic: LOVES water Hydrophobic: HATES water Hydrophilic: LOVES water 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 Function: Keeps the membrane together; the phosphate heads are not attached to each other Location: Found in between the phospholipids in the bilayer.

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

Proteins Location: Within the phospholipid bilayer

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

Transport Proteins Helps larger substances pass through the bilayer

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

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 Weeee!!! HIGH LOW

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

Diffusion At Equilibrium HIGH LOW Molecules still move around (concentration gradient) 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 LOW HIGH

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

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

Iso, Hypo or Hyper? 10% Na. CL 90% H 2 O ISOTONIC ENVIRONMENT CELL 10% Na. CL 90% H 2 O

Water goes? IN/OUT 10% Na. CL 90% H 2 O CELL 10% Na. CL 90% H 2 O

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

Water goes? 10% Na. CL 90% H 2 O IN ENVIRONMENT CELL 20% Na. CL 80% H 2 O

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

Water goes? 10% Na. CL 90% H 2 O OUT ENVIRONMENT CELL 5% Na. CL 95% H 2 O