All animals and plants are made of cells. Animal and plant cells have features in common, such as a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a cell wall, and often have chloroplasts and a permanent vacuole. Note that cells may be specialised to carry out a particular function.

We use microscopes to see very tiny structures such as cells.

Bacterial cell structure

Bacterial cells are much smaller than plant or animal cells. They were first seen under a microscope by Anton van Leeuwenhoek in 1676. As microscopes have improved, scientists have come to understand bacterial cell structure better.

Using electron microscopes we now know that bacteria have a cell wall. This is similar to a plant cell wall but is more flexible. Bacteria do not have a nucleus. They do have two types of DNA – plasmid and chromosomal. The chromosomal DNA carries most of the genetic information. Plasmid DNA forms small loops and carries extra information. Some bacteria have a flagellum – a whip like tail. This helps the bacteria to move itself along. When we talk about these flagellum tails in multiple bacteria, we call them flagella.

Structure of a salmonella bacterium cell

Structure of a bacteria cell

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The Building Blocks of Cells Apunte sobre What's in a cell?, creado por beloni.fred el 16/06/2013.

What's in a cell?