Introduction

    This week, you will begin to learn about cells.  This is important for you to begin to understand all living organisms as well as to understand cancer.  You are reading Chapter 4 in your text book.  We will finish this chapter next week.  I have also included an "organelle" review sheet which you can begin to fill out on your own at home.  This should help guide your studying.

    Your book says that all cells have 3 things in common:

1. They are surrounded by a membrane
2. They have a DNA-containing region
3. They have cytoplasm, which is all the stuff inside the membrane except for the DNA-containing area.

Be sure to keep this in mind as you learn about cells!  It is so easy to forget these important, big ideas as you go on to learn about the details.

Cells are bordered by membranes

    A cell is surrounded by a membrane.  This membrane has to be flexible, so that the cell can undergo changes, but also has to be tough, so that the cell doesn't burst.  You will be learning about the structure and function of membranes in this lesson.

Cell Fluids and Internal Structures

    People talk about cells as being filled with a thick fluid.  In fact, the fluid is thick because it contains many things dissolved in it, but there are more things in the fluid than that-- there are also lots of undissolved items.  Some of these undissolved items are bounded by membranes (like a little bag inside a larger one); the nucleus of the cell is one such item.  Other undissolved items that are not wrapped by membrane exist as well.  Many of these internal structures within the fluid are called organelles.  The fluid inside the cell, including all the organelles and undissolved materials except for the nucleus, is called the cytoplasm.   So, the cytoplasm + nucleus + cell membrane = cell.

    One can also describe just the fluid of the cytoplasm.  If you could pick out all the undissolved items from the cytoplasm, you would have the cytosol, which is water with dissolved materials in it.

Navigate through the organelles:

    Here's an image of a cell that I have turned into a clickable image.  You can click on any organelle that is part of this week's lesson and immediately head to the page that describes it.  Next week I will post this image again, but the entire thing will be clickable!

Organelle classification

    On the next page you will learn about two different types of cells.  Only one of them, the eukaryotic cells, have the organelles I am describing here.  However, I wanted to set up a way to learn and study the organelles, so here goes:

    I like to classify all the organelles of a cell into particular groupings by function or location.  Here are the groups I think are helpful to distinguish:

I hope you find this organizational scheme useful.

© 2006 STCC Foundation Press, content by Dawn A. Tamarkin, Ph.D.

Last changed: January 21, 2007