- These are microscopic single-celled organisms.
- The three basic shapes of these are: spheres, rods and spirals.
Features of bacteria:
- They have no real nucleus but contain a single circular chromosome.
- They also have a plasmid which is a small singular ring of DNA that can contain genes for antibiotic resistance. Can be used in genetic engineering as vectors.
- Have a cell membrane and cell wall (made of carbohydrates and proteins).
- A slime capsule.
- Some have a flagellum or flagella to move.
- Reproduce asexually by binary fission every 20 minutes.
- They obtain nutrition mainly by feeding off other living or dead organisms, but many bacteria are important autotrophs, which carry out photosynthesis.
- There are useful bacteria to humans such as lactobacillus bulgaricus used in making yoghurt from milk.
- Others are pathogens such as Pneumococcus which causes pneumonia.