Microbes STRUCTURE Bacteria Are smaller than cells BUT

Microbes

STRUCTURE

Bacteria -Are smaller than cells BUT bigger than viruses They have… 1. A cell membrane 2. A cell wall 3. Cytoplasm 4. Genes -They contain no nucleus - only a chromosome that is in a circle. We call this a plasmid. .

A diagram of a Bacteria

If we wanted to measure a single bacterium, its length would range from: 1 mm to 1000 1 mm 20 If a full stop is 1 mm wide how many bacteria could you line up along it? Between 1000 and 20 bacteria would fit on a full stop!

Bacteria This bacteria is called Salmonella It lives in eggs and chicken. This bacteria is called E Coli. It lives all over the place.

Bacteria

Viruses -Viruses are very small They live in things! -They are made up of a few genes inside a protein exterior

Viruses - how small? Viruses are very different to bacteria because they do not have a cellular structure and are much smaller. Bacteria are 100 times smaller than a human cell. Viruses are 1000 times smaller than a bacteria. So how small are viruses compared to a human cell? 100 000 times smaller!

Viruses and tennis balls! Here’s another way to think about the size of viruses. . . If a common cold virus was the size of a tennis ball, how big would a nose be? A. the size of a supermarket B. the size of Birmingham C. the size of Wales

A diagram of a virus

Viruses H. I. V. T-2 Phage. They are 1000 s of times smaller than bacteria These micro-organisms are not really alive. They can only ‘ live ’ when they infect a living cell.

Fungi When you see a mushroom, it is just the “fruiting body” of a fungus living underground.

Fungi Like some bacteria, fungi also break down dead organisms.

Under attack! Firstly, as soon as a virus or bacterium enters the body, we are termed infected This is not the same as being ill. Illness results from the effects these microbes have on our body. Bacteria and viruses have the ability to produce poisons known as. . . TOXINS

Under attack! When the microbe enters the body, it begins releasing these toxins which can damage body tissue and prevent body systems working properly. The body could probably cope with a small amount of poison, but microbes quickly reproduce themselves. If the microbes reproduce… We are said to be diseased. more microbes mean that more toxin produced… our normal state of well being is affected…

Diagram of a microbe attack These symbols and colours represent the process of becoming infected and then ill: 1 Person is well. The microbe levels are very low and the toxin levels are very low. 2 Person is infected. The microbe levels are low and the toxin levels are low. Toxin Levels Presence of microbes 3 Person is ill and diseased. The microbe levels are high and the toxin levels are high.

Bacteria reproduction This means that if 1 bacterium enters your body at 8. 00 am, 4 hours later, you would have 4096 bacteria within your body! Do viruses reproduce in the same way as bacteria? No!

The bacteria will then reproduce ……

Virus reproduction Viruses need a host cell to reproduce within. This is a body cell, which will provide the machinery, and chemicals the virus requires to make copies of it. host cell e. g. a human body cell virus

The process of host cell infection Therefore the virus not only infects the body; it also infects the body cells. 1. Approach The virus approaches the host cell 2. Attachment The virus secures itself to the surface of the host cell.

3. Insertion The virus injects its genetic material through the injection tube and into the host cell. 4. Replication The genetic material makes multiple copies of itself.

5. Assembly New viruses are assembled using chemicals from the host cell. The original virus dies and breaks down. It is at this stage that the viruses within the host cell can remain dormant. In other words, they sit within the cell without killing it or breaking out. With some viruses such as HIV, this period can last a number of years. This is why people can remain infected with HIV without realizing they are infected.

6. Cell Lysis (cell breaks) - toxin The host cell splits open and dies. The viruses escape and release toxins. Each virus will then start another round of replication.