Beyond the Microscope Mid-module

Bacteria is the second smallest type of cell!

Some types of bacteria create their own food whereas others consume organic material. This means that they can live on a wide range of sources (sun, food and chemicals)  and can exploit a wide range of habitats (humans, animals, food, sea bed etc.).

Bacteria need the right conditions (moisture, oxygen, glucose and warmth) for rapid reproduction which can lead to disease and food spoilage.

Bacteria have: a flagellum (allows movement), a cell wall (to keep cell shape and prevent bursting) and bacterial DNA (to control the cell's activities and replictaion). Bacteria cells do not have any chloroplasts, mitchondria, a nucleus or a vacuole.

Bacteria grow in number using a type of asexual reproduction called binary fission. This just allows the cells to split in 2. Bacteria can be grown in large fermenters where they can divide every 30 seconds.

There are 4 types of bacteria: Curved Rod, Spherical, Rod and Spiral.

These 3 scientists made significant discoveries towards the biological world!

Louis Pastor - In the 1860s, he completed a series of experiments that proved that microorganisms in the air caused food to go bad and not the air itself.

Joseph Lister - He noticed that wounds became infected after operations. In 1865, he started spraying wounds with carbolic acid . This killed microorganisms and so the wound did not become infected. He had discovered the first antiseptic.

Alexander Fleming - In 1928, he discovered penicillin. He had accidentally left some samples of bacteria open to the air and a few days later, he had noticed that the samples had gone mouldy. He observed that where the mould grew, the bacteria had stopped growing . This mould was penicillium and was the world's first antibiotic. Penicillin is still used to cure bacterial infections.

Viruses are the smallest type of organism!

Viruses are not considered as living things as they can only reproduce inside other living cells. Viruses can only attack specific cells and can infect plant, animal and bacterial cells.

The antigens of the virus must match and be compatible with the antigens of the other cell in order for the virus to affect it.

A virus is made up of a protein coat, antigens and a strand of genetic material.

Viruses reproduce with these 4 steps:

• The virus attaches itself to specific host cells
• The virus then injects its genetic material or DNA into the host cell
• It then uses the cells own components to create new viruses
• The host cell splits open releasing the new viruses