1. Microorganisms

2. Starter
What do these foods have in common?

3. Interesting Facts
Microbes first appeared on earth about 3.5 billion yrs ago, before any other organsim. (humans have only been around for less that a million years)
Microbes are so tiny that a billion of them would fit on a 10 cent piece.
There are more types of microbes than any other species on the earth, they make up 60% of all living matter.
Microbes are ubiquitous (everywhere). There’s about 10 million bacteria on each of your feet.

4. Interesting Facts
We have only known about microbes for about 350 years, when the first microscope was invented.
Microbes were only linked to disease in the late 1800s.

5. Who are the Microbes?
Bacteria
Fungi
Algae
Protozoa
Viruses

6. What are Microbes?
Very small organisms you cannot see with the naked eye
These organisms are unicellular – a single cell that carries out the processes of life.
Some are harmful and cause disease by releasing toxins – pathogens
Others can be beneficial – yoghurt, bread, compost
Some feed on dead and decaying material - saprophytes

7. Bacteria They are very small, it length can range from
They are everywhere over your skin , in the air and living inside you 1
1000 20 mm to

8. Bacterial Shapes

9. Bacterial Structure

10. Structures explained
Most bacteria have a thick outer covering called the cell wall. Just within the cell wall is the cell membrane which allows substances to be transported in and out of the cell. Along the surface of the bacteria cell, you might encounter structures called pilus, whose job is to help the bacteria stick to surfaces. Bacteria might also need to move around in their environment, so they can have structures called flagella, which resemble tails. The watery interior of the cell is called cytoplasm, and it has the texture of jelly. Sprinkled throughout the cell are small roundish structures called ribosomes. Ribosomes make proteins for the cell. Every prokaryote cell has DNA floating within the cytoplasm, which usually looks like a twisted strand of spaghetti. DNA contains the instructions for the cell, basically it is the control centre.

11. Bacteria are Living ThingsM R S G E N

12. Reproduction

13. Bacterial Reproduction
Remember, in ideal conditions, some bacteria can reproduce as often as once every 20 minutes.
E.g.
Time (Min)
No of Bact 1
200
1024 40 4
240
4096 80 16
280
16 384
120 64
320
65 536
160
256
360

14. Graph of Bacterial Numbers Against Time
Number of Bacteria
Time (min)

15. Bacterial Growth

16. Bacterial Growth
The rapid increase in numbers in the steep part of the graph is called exponential growth.
This will not continue, eventually lack of food or space or a build-up of toxic waste products will cause the number of bacteria to level off and then decrease.

17. Conditions Needed for Bacterial Growth
Energy
Moisture
Warmth
Oxygen pH

18. Bacterial Spore Formation
If conditions for bacterial growth are unsuitable, bacteria may secrete a thick spore wall and survive for years.
If conditions become suitable, the spore wall will rupture and the bacteria will resume growth.

19. Bacterial Nutrition
Most bacteria are consumers – they don’t make their own food.
Parasitic Bacteria feed off living material.
Saprophytic Bacteria live on dead plant or animal material.

20. Bacterial Nutrition
Bacteria feed by producing enzymes, which pass through the cell membrane and break food down outside the bacteria.
The broken-down food then enters the bacteria through the cell membrane.
This is called extracellular digestion.

21. Bacterial Excretion Bacteria excrete waste products
Sometimes these are harmful and are known as toxins.

22. Bacterial Respiration
Respiration is the process of obtaining energy by chemically breaking down food.
Most bacteria respire aerobically.
Some bacteria respire anaerobically (some bacteria may be killed by oxygen)