Understanding Microbes Flashcards
Bacterial cells have certain features that allow them to survive. These include:
- A flagellum for movement
- A cell wall to maintain shape and to stop it from bursting
- DNA to control the cell’s activities and replication of the cell
Bacterial cells can be different shapes such as:
- Spherical
- Rod shaped
- Spiral
- Or curved rods
Binary fusion
Bacteria reproduce by splitting into two in a type of asexual reproduction called binary fusion.
Aseptic technique
It is possible to get bacteria to reproduce on an agar plate but all equipment must be sterilised first to prevent contamination by other microbes.This is called aseptic technique.
In terms of numbers, bacteria are very successful for several reasons:
- They can survive on an enormous range of different energy sources.
- They can live in a very wide range of habitats.
- Some bacteria live by taking in organic nutrients but others can make their own food.
Bacteria can reproduce very quickly.
This means that they can very rapidly spoil food or cause disease. This means that they must be handled carefully to avoid contamination of people, animals or food.
Yeast is a single-celled fungus that is grown for many functions. Its growth rate can be altered by:
- Changing food availability
- Changing temperature
- Changing pH
- Removing waste products
Doubling Yeast growth
The growth rate of yeast doubles for every 10 ºC rise in temperature until the optimum is reached.
What are viruses?
Viruses are not living cells but very small structures made of a protein coat surrounding a strand of genetic material.
Viruses can only reproduce under certain circumstances:
- They only reproduce in other living cells.
- They only attack specific cells, which may be plant, bacterial or animal cells.
When a virus reproduces it will:
- Attach itself to a specific host cell
- Inject its genetic material into the cell
- Use the cell to make the components of new viruses
- Cause the host cell to split open and die to release the viruses
