Cell biology

Living organisms are made up of cells. Understanding the structures and functions of cells is the key to understanding how whole organisms work and interact with the world around them.

How does your body recognise an invading pathogen? How do cells communicate so they can act as a coordinated whole? Why are transplanttransplant
The process of replacing a damaged or diseased organ with a healthy organ from a dead or living donor. ed organs rejected without immunosuppressantimmunosuppressant
Medicines which prevent the immune response of the body from destroying a transplanted organ. drugs? What are the differences between your cells and those of bacteriabacteria
Single-celled organism. Has a cell wall, cell membrane, cytoplasm. Its DNA is loosely-coiled in the cytoplasm and there is no distinct nucleus. ?

The size and structure of cells varies enormously, but there are many common features. The cell surface membranemembrane
A thin, flexible sheet-like structure that acts as a lining or a boundary in an organism. forms a barrier between the contents of the cell and the environment. Membranes also surround all the organellesorganelles
A distinct part of the cell, such as the nucleus, ribosome or mitochondrion, which has structure and function. inside the cell. The structure of these membranes affects the functioning of almost every aspect of the cell.

Cells act as biological factories, producing many different substances which need to be exported to different regions of the cell or the body. Often these substances are produced as a result of signals from inside or outside the cell itself.

Cells display complex identification systems on their surfaces, and these act as part of overall cell communication. These systems are sometimes used by pathogens to gain entry to cells – and both surface identification systems and internal communication cascades can be used as targets for drugs in the battle against disease.