What are bacteria?
Bacteria are among the smallest living things. A single bacterium consists of just one cell, and is called a single-celled, or unicellular organism.
Even though it is just a single cell, it can carry out all seven life processes:
- movement - all living things move, even plants
- respiration - getting energy from food
- sensitivity - detecting changes in the surroundings
- growth - all living things grow
- reproduction - making more living things of the same type
- excretion - getting rid of waste
- nutrition - taking in and using food
What鈥檚 in a bacterium?
There are similarities between plant and animal cells and a bacterium. They all share a cell membrane and cytoplasm. Bacterium also have a cell wall around them, like plant cells. However unlike most plant and animal cells, it has no nucleus. Instead, it has a circular strand of DNA, called a plasmid, that floats in the cytoplasm.
There are millions of different types of bacteria. Different types of bacteria have different shapes.
Many types of bacteria have extra cell structures to help them to survive. For example, they may have:
- Flagella - tail-like structures that allow bacteria to move through liquids
- A slime capsule - outside the cell wall, to protect them and stop the bacterium drying out.