Cells Unpacked – A look inside | British Society for Cell Biology

Please read this section before ‘pulling the zip’ to ‘unpack the cell’.

Unpacking a cell is rather like unpacking a travel bag. Each item in the bag has a function and is of some interest, but without the other items it might have limited use or no use at all. The contents of the travel bag needs to be viewed as a working system for a business conference or a holiday in the sun.So it is with a cell. We can unpack it and be fascinated by each item but we need to remember that the items work together as a system, communicating and linking with each other. This is a clear case of the whole being greater than the sum of the parts.
We hope you will find these ‘learning pages’ provide some interesting snapshots about cell biology. For more detailed information you are advised to look at some of the excellent and well-illustrated modern textbooks on cell biology.

What is inside a cell?
Very basically a cell contains a set of plans and operating instructions together with a set of equipment to turn these plans into actions, to build constructions and set up operating systems.
These plans, instructions and systems are surrounded by a membrane (the plasma membrane). This helps to keep the cell together as a working unit and enables chemicals and messages to enter it and leave it in a controlled way. A material called extracellular matrix often surrounds cells. In some animal cells it is almost as important as the cytoplasm on the other side of the plasma membrane. In plant cells it is present as a cellulose wall.

The set of plans and operating instructions in higher cells (eucaryotes) are located in a special enclosed area inside the cell called the nucleus. The plans and instructions are for a particular cell. When this cell divides the plans and operating instructions are copied. The material in the nucleus is mainly DNA.

The rest of the cell, called the cytoplasm, contains parts of the cell that carry out instructions from the nucleus. These include releasing energy from food, making proteins, creating movement and communicating with other cells.

Plant cells also have, in addition, a cellulose wall surrounding the plasma membrane.
In bacteria (prokaryotes) the genetic material (mainly DNA) is not enclosed within a special sac, so no nucleus is present. Very few organelles are present and there is no extracellular matrix.

You can ‘unpack’ the cell and find out more by ‘clicking’ on a name in the following list: