Movement Through the Cell Membrane

Movement Through the Cell Membrane

Cellular Movement All living organisms rely on diffusion Get oxygen for respiration Removing waste products Transpiration in plants

Cellular Movement The cell membrane helps to regulate what moves into and out of the cell

The Cell Membrane The cell membrane is like a soap bubble. Flexible membrane Seals the inside of the cell from its outside environment

The Cell Membrane All cells have a cell membrane Function: a. Regulates what enters and exits the cell to maintain an internal balance called homeostasis b. Provides protection and support for the cell c. Takes in food and water and eliminates wastes

The Cell Membrane The cell membrane is made up of a double layered sheet known as the phospholipid bilayer

The Cell Membrane Structure a. Phosphate head is hydrophylic b. Fatty acid tails hydrophobic Phospholipid Lipid Bilayer

The Cell Membrane The cell membrane Is a mosaic of many different molecules And is fluid due to the movement of its molecules

The Cell Membrane Cell membrane is selectively permeable It has pores (holes) in it which allows some molecules in and keeps other molecules out This structure helps it be selective! Pore Proteins Carbohydrate chains Cell membrane Protein channel Lipid bilayer

The Cell Membrane Review Lipid Bilayer Outside of cell Proteins Carbohydrate chains Transport Protein Inside of cell (cytoplasm) Phospholipids

Types of Cellular Transport Passive Transport - doesn t use energy 1. Diffusion 2. Osmosis 3. Facilitated Diffusion Active Transport -uses energy 1. Protein Pumps 2. Exocytosis high 3. Endocytosis high Weeee!!! low This is gonna be hard work!! low

Passive Transport Molecules move randomly Area of high concentration to an area of low concentration. Weeee!!! high low

1. Diffusion Diffusion continues until all molecules are evenly spaced (equilibrium is reached)-note: molecules will still move around but stay spread out.

1. Diffusion Gas exchange at the alveoli and blood Gas exchange for photosynthesis through the stomata Gas exchange for respiration

2. Osmosis Diffusion of water through a selectively permeable membrane

2. Osmosis Absorption of water by plant roots Re-absorption of water in the kidneys Absorption of water by the alimentary canal

2. Osmosis Water is so small and there is so much of it, the cell can t control it s movement through the cell membrane.

2. Osmosis at work When there are more water molecules OUTSIDE the cell, water moves INTO the cell. The Cell swells.

2. Osmosis at work When there are more water molecules INSIDE the cell, water moves OUT OF the cell the Cell shrinks.

2. Osmosis at work Effect of salt Salt makes water move out of the cell so it dries the cell out

2. Osmosis at work Different Solutions HYPERTONIC: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) Water moves across the membrane out of the cell

Hypertonic Solution Hypertonic: shrinks Result: Water moves from inside the cell.out into the solution: Cell shrinks (Plasmolysis)!

2. Osmosis at work Different Solutions HYPOTONIC: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water) Water moves across the membrane into the cell

Hypotonic Solution Hypotonic: swells Result: Water moves from the solution to inside the cell: Cell swells and bursts open (cytolysis)!

2. Osmosis at work Different Solutions HYPOTONIC: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Equal solute; Equal water) Water moves across the membrane into the cell

Isotonic Solution Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic: (equal solute; equal water) Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

What type of solution are these cells in? A B C Hypertonic Isotonic Hypotonic

How Organisms Deal with Osmotic Pressure In plants, the pressure exerted on the cell wall is called tugor pressure. Effect of Osmosis on Plant Cells

3. Facilitated Diffusion Certain molecules are able to diffuse directly across the lipid bilayer (simple diffusion) while others diffuse across the membrane differently (facilitated diffusion)

3. Facilitated Diffusion Glucose Amino acids

3. Facilitated Diffusion Carrier Proteins- allow the diffusion of molecules across the membrane if they are unable to cross via the cell membrane.

3. Facilitated Diffusion Much like the Shape-O toy, protein channels are specific to certain kinds of molecules.

Active Transport Definition The movement of material against the concentration gradient, that is from an area of low concentration to an area of high concentration

Active Transport this type of transport requires energy in the form of ATP.

Active Transport Re-absorption of products in the kidney Sodium and potassium in cell membranes

Active Transport Actively moves molecules to where they are needed Different types: *Protein Pump Endocytosis Exocytosis

1. Protein Pumps Transport Proteins move ions against the force of diffusion Example: sodium / potassium pump are important in nerve responses. Show video clip Protein changes shape to move molecules: this requires energy!

1. Protein Pumps Sodium Potassium Pumps (Active Transport using proteins) How Does This Happen? Solute binds to protein Mitochondria provides energy that changes the shape of the protein Change in shape allows solute to be moved across membrane System resets

Active Transport Key fact: ALL forms of active transport require... ENERGY!!!

Types of Cellular Transport This is a great review of all the cellular transport processes http://www.northland.cc.mn.us/biology/ Biology1111/animations/active1.swf Cellular Movement