Daily Newsletter

September 3, 2012 The Nature of the Cell

The cell theory describes the importance of the cells to biologists. How important is it? Well the first part of the cell theory answers that: All known living things are made up of one or more cells. But what ultimately is a cell? What takes place in one? Why are they so important?

It will take a few discussions to get to all these questions, but there is a starting point. As a basic description, the cell is a self-managing, self-contained chemical factory. Cells take in materials, use these for energy and building blocks, and then produce materials to keep the cell healthy, harvest nutrients, eliminates waste, and produces products. The cell has many components to accomplish these tasks: DNA for management, chemical signals to send messages, enzymes for chemical activity, etc....

Let's look at the analogy of a chemical factory: Inside a factory, there are going to be different processing places for different chemicals. There are going to be pathways of pipes going between vats and other structures. Taking a further look back, there is a building, with trucks coming and going.

Inside of the cell, chemical reactions will be taking place. Outside the cell, chemical reactions are taking place. Are they the same chemical reactions? One of the foundations of cells is that the inside of a cell is a spatial area with a defined concentration of a variety of chemicals that is distinct and different from the chemical concentrations found outside of the cell.

So, there is an inside and outside of a cell, and they are different.

You will hear me say again and again that the cell membrane is the defining structure of a cell. Why? Because it establishes the boundary. When you have a cell membrane, you can have an inside as opposed to an outside of a cell. If you loose that membrane, you start moving to a full equilibrium between the inside and outside of the cell. If you loose the membrane, or it gets holes, the cell dies. The cell dies when you cease to have an inside vs. an outside.

The fastest way to kill a cell is to poke holes in it.

Daily Challenge: The cell membrane
Today, I want you to discuss the basic structure and functions of the cell membrane, focusing on this idea that it provides the essential, and foundational, separation between the inside and outside.