1 Movement through Cell Membranes Movement through Cell Membranes- Gateway to the Cell

2 Cell Membrane controls Homeostasis inside It balances the inside and outside of the cell. Homeostasis is maintained by plasma membrane controlling what enters & leaves the cell

3 Structure of the Cell Membrane

4 PhospholipidsCholesterol Proteins Carbohydrates (glucose) Membrane Components

5 LABEL THE STRUCTURES Phospholipid bilary Carbohydrate chain Protein Channel Cholesterol

6Phospholipids Make up the cell membrane Contains 2 fatty acid chains called the tails Contains one glycerol called the head.

7 hydrophilic Heads are hydrophilic “water loving” hydrophobic Tails are hydrophobic “water fearing” Cell Membrane Makes membrane “Selective” in what crosses

8 Cell Membrane Hydrophobic molecules pass easily; hydrophilic DO NOT phospholipids bilayer The cell membrane is made of 2 layers of phospholipids called the lipid bilayer

9 Small molecules and larger hydrophobic molecules move through easily. e.g. O 2, CO 2, H 2 O Semipermeable Membrane

10 Ions, hydrophilic molecules larger than water, and large molecules such as proteins do not move through the membrane on their own. Semipermeable Membrane

11 Types of Transport Across Cell Membranes

12 Simple Diffusion NO Requires NO energy HIGH to LOW Molecules move from area of HIGH to LOW concentration

Diffusion Two things need to happen in a cell in order for diffusion to occur… what are they? 13 1.Cell membrane must be permeable to that substance. 2.There must be a concentration gradient (needs to be higher in one area and move to lower area)

14 DIFFUSION PASSIVE Diffusion is a PASSIVE process which means no energy is used to make the molecules move, they have a natural ENERGY

15 Diffusion of Liquids

Sugar Cube Diffusion 16

17 Diffusion through a Membrane Cell membrane Solute moves DOWN concentration gradient (HIGH to LOW)

18 Osmosis Diffusion of water across a membraneDiffusion of water across a membrane Moves from HIGH water potential (low solute) to LOW water potential (high solute)Moves from HIGH water potential (low solute) to LOW water potential (high solute)

19 Diffusion of H 2 O Across A Membrane (Osmosis) High H 2 O potential Low solute concentration Low H 2 O potential High solute concentration 1. The left side concentration is what? 2.The right side concentration is what? So which way does water move?

20 Cell in Isotonic Solution What is the direction of water movement? The cell is in _______________. equilibrium CELL 10% NaCL 90% H 2 O 10% NaCL 90% H 2 O ENVIRONMENT NO NET MOVEMENT

21 Cell in Hypotonic Solution What is the direction of water movement? Water moves into the cell CELL 10% NaCL 90% H 2 O 20% NaCL 80% H 2 O H2O

22 Cell in Hypertonic Solution What is the direction of water movement? Water moves out of the cell. CELL 15% NaCL 85% H 2 O 5% NaCL 95% H 2 O ENVIRONMENT H2O

23 Isotonic Solution NO NET MOVEMENT OF H 2 O (equal amounts entering & leaving) Hypotonic Solution Water enters cell- can cause it to burst Hypertonic Solution Water leaves cell until it “deflates”