THE CELL MEMBRANE And other membranes Cell Organelle

THE CELL MEMBRANE And other membranes

Cell Organelle Anything you do is actually done by your cells working together. Example: Digestion, where you take in food, break it down and release the wastes. Many organelle are made of membranes.

Taking in Food & Water Enters cell through cell membrane, which is: Selectively permeable: only lets in certain molecules (Fully permeable means everything can get in)

Cell membrane Membranes are made of 2 layers of fats, which is called a Lipid bilayer Within bilayer, there also other chemicals Allow for identification, act as channels “Fluid Mosaic Model” of membranes Very flexible, lots of different molecules in it Can be pierced by needle, and will reform

Other Organelle Made of Membrane Mitochondrion Chloroplast Endoplasmic reticulum Golgi body Vacuole Nucleus Lysosome

Water & Oxygen Get In By “Passive Transport”: Movement of molecules through a membrane without the use of energy Three types: Diffusion Facilitated Osmosis Diffusion

Diffusion � � Definition: The movement of substances from an area of high concentration to an area of low concentration. Concentration refers to the amount of molecules in the solution.

Facilitated Diffusion In cell membrane, some proteins make channels for special molecules (like glucose) to get through.

Osmosis Definition: The movement of water through a membrane from an area with lots of water to an area with less water.

Osmotic solutions � Osmosis occurs between two types of solutions: � Hypertonic (where the concentration is higher) � Hypotonic (where the concentration is lower) � Water will move from hypertonic to hypotonic

Dynamic Equilibrium When there’s the same concentration on one side of the membrane as another, a balance is reached. Called Dynamic Equilibrium

Importance For Cells If cells are hypertonic to the blood, water will diffuse in (and cell may burst) If cells are hypotonic to the blood, their water will diffuse into the blood

Practice Questions One last look Page 64 # 1, 2, 4, 6, 7, 8