Cell Membrane and Transport
Liz C, Maddy Z, Livy P, Lauren S, & Melanie Z
The Plasma Membrane
The plasma membrane is an external wall like structure surrounding a cell, creating a boundary for the cytoplasm and regulates the travel of molecules in and out of the cytoplasm. The membrane being made up of lipids and proteins. One layer of the Plasma membrane is called the Phospholipid Bilayer. This is two layers made up of phosphate and lipid molecules, which forms a cell membrane. The first layer is call Hydrophilic, this is the polar heads of phospholipids. The second layer is called Hydrophobic, this is a layer of non-polar heads of phospholipids. These layers can be demonstrated in a fluid mosaic model. This model will show the cholesterol, a compound found in body tissue, Glycolipids and Glycoproteins.
Cellular Transport
Concentration Gradient is the gradual decrease in concentration over a distance. The concentration moves from high to low concentration. Look below at the first picture to the right to help you understand concentration gradient better.
Simple Diffusion is the movement of particles from high concentration until equilibrium occurs. Factors that affect the rate of diffusion are temperature, concentration, and pressure. An example of simple diffusion is putting food coloring into water. Look at the picture below in the middle to help you understand simple diffusion better.
Facilitated Diffusion is when certain molecules cross membranes by binding with a carrier protein. Look at the picture below on the left to help you understand facilitated diffusion better.
Osmosis
Isotonic
The isotonic solution is the concentration of solutes is equal in and out of the cell.
The cell maintains it shape, it does not shrivel or increase in size.
Hypotonic
The hypotonic solution is the concentration the solution is much lower on the outside of the cell. The water moves into the cell, and if animals cells swell and burst, while the plant cell wall prevents it from bursting. In this solution H2o goes from “high-->low”.