Unit 7.1 Microorganism

A micro-organism is a living organism so small that we can only see it when we use a microscope. Micro-organisms are made of cells, like all living organisms. Most micro-organisms are made of only one cell.

• Bacteria are microscopic, single-celled organisms that exist in their millions, in every environment, both inside and outside other organisms

• Spherical: Bacteria shaped like a ball are called cocci, and a single bacterium is a coccus. Examples include the streptococcus group, responsible for "strep throat."

Rod-shaped: These are known as bacilli (singular bacillus). Some rod-shaped bacteria are curved. These are known as vibrio. Examples of rod-shaped bacteria include Bacillus anthracis (B. anthracis), or anthrax.

Spiral: These are known as spirilla (singular spirillus). If their coil is very tight they are known as spirochetes. Leptospirosis,  Lyme disease, and syphilis are caused by bacteria of this shape.

Fungi includes mushrooms and toadstools.  Yeast is an example of  a single-celled microscopic fungus.

Algae: are a type of plant-like living things that can make food from sunlight by photosynthesis.

Protozoa: Protozoa are single celled organisms. They live in a wide variety of moist habitats including fresh water, marine environments and the soil.