BASIC STRUCTURE OF A CELL MEMBRANE The cell membrane surrounds all living cells, and is the cell's most important organelle. It controls how substances can move in and out of the cell and is responsible for many other properties of the cell as well. The membranes that surround the nucleus and other organelles are almost identical to the cell membrane. Membranes are composed of phospholipids, proteins and carbohydrates arranged in a fluid mosaic structure. SIMPLE OR LIPID DIFFUSION A few substances can diffuse directly through the lipid bilayer, part of the membrane. The only substances that can do this are lipid-soluble molecules such as steroids, or very small molecules, such as H2O, O2 and CO2. For these molecules the membrane is no barrier at all. Since lipid diffusion is (obviously) a passive diffusion process, no energy is involved and substances can only move down their concentration gradient. Lipid diffusion cannot be controlled by the cell, in the sense of being switched on or off. It is controlled by the concept of equilibrium. The molecules move from a r....

Don't want to risk posting your essay or term paper?

Get INSTANT UNLIMITED ACCESS to This Essay and
Over 15,000 Other Quality Essays & Term Papers!

View This Essay Now ($12.99)

• To view the rest of this How Substances Enter and Exit a Living Cell free essay you must submit one complete, good quality essay or term paper of your own to us.
Only multi-paged (this means 2 pages or more), high quality essays & term papers will be accepted!

• After submission, your essay will be read by our staff members to ensure quality and completeness. If your submission passes our review process you will receive an email back with the complete 'How Substances Enter and Exit a Living Cell' free essay in it.

• We only accept a limited number of submissions each day and essay and term paper review normally takes our staff up to 24 hours.

STOLEN, COPIED, WIKIPEDIA or BORROWED Essays = REJECTED

Low quality and junk submissions = REJECTED

Essays & term papers not useful to others = REJECTED

Fresh, useful & unplagerized essays = FREE ESSAY IN RETURN

Free Essays is protected by:

Category:

Mis-categorized submissions will automatically be rejected!

Essay Title:

The Complete Essay:
(include works cited if available)

You are wasting your time if you submit a poor quality, fake, stolen, incomplete or too short of an essay!

Class Level & Notes:

What class and grade level was this essay written for? What grade did it receive? Include any teacher notes that you think might be helpful for the next person. Anything you write here WILL NOT effect whether you receive an essay back.
EXAMPLE: High School Junior English. C+ grade. Teacher said paper was too long.

Your Email:

If accepted, your free essay will be emailed here.

Terms and Conditions:
By clicking Submit, you agree to the following terms and conditions listed below. In return for your submission, assuming it passes our review process, you will receive the following How Substances Enter and Exit a Living Cell free essay or term paper from us:

The information you are submitting is original and does not violate the copyright laws of anyone else.
You are over the age of 18 and are the sole owner and copyright holder of the information you are submitting.
You agree to give up all rights (including, but not limited to, copyright, property, intellectual, material) on all submitted materials and the ownership and copyright of this material becomes the sole property of Free Essays LLC
You agree to never take legal action against Free Essays LLC or any of their subsiduaries.