This tutorial introduces cell membranes. Other sections include plants, animal systems, invertebrates, vertebrates, and microorganisms. The site has sections on cell structure, cell function, the scientific method, classification, microorganisms, invertebrates, plants, what is the function of enzymes in the cell membrane, and animal systems. 1997-2017 by Andrew Rader Studios, All rights reserved. Whether you are a single cell or a blue whale with trillions of cells, you are still made of cells.
When you think about a membrane, imagine it is like a big plastic bag with some tiny holes. That bag holds all of the cell pieces and fluids inside the cell and keeps any nasty things outside the cell. The holes are there to let some things move in and out of the cell. The cell membrane is not a solid structure. It is made of millions of smaller molecules that create a flexible and porous container. The phospholipids make the basic bag. The proteins are found around the holes and help move molecules in and out of the cell. There are also proteins attached to the inner and outer surfaces of the membrane.
Scientists use the fluid mosaic model to describe the organization of phospholipids and proteins. The model shows you that phospholipid molecules are shaped with a head and a tail region. Scientists have shown that many proteins float in the lipid bilayer. Some are permanently attached while others are only attached temporarily. Some are only attached to the inner or outer layer of the membrane while the transmembrane proteins pass through the entire structure. As you learn more about cell organelles, you will find that they all have a membrane. Organelle membranes do not have the same chemical makeup as the cell membrane. They have different lipids and proteins that make them unique.
Common uses of enzymes in industry organelles have two membranes. The outer membrane contains the mitochondrion parts. The inner membrane holds digestive enzymes that break down food. While we talk about membranes all the time, you should remember they all use a basic phospholipid bilayer structure, but you will find many variations throughout the cell. 1997-2017 Andrew Rader Studios, All rights reserved.