To understand how micro-organisms cause illness Thursday, June 23, 2016
Who is diseased???
1 bacterium divides every 20mins, how many will there be after 16hrs? 281, 474, 976, 710, 656
11 22 44 88 16 32 64 128 256 512 1024 2048 Bacterial Reproduction 4096 8192 1.34x10 8 2.68x10 8 5.37x10 8 1.07x10 9 2.15x10 9 4.29x10 9 8.59x10 9 1.72x10 10 3.44x10 10 6.87x10 10 1.37x10 11 2.75x10 11 5.5x10 11 1.1x10 12 2.2x10 12 4.4x10 12 8.8x10 12 1.76x10 13 3.52x10 13 7.04x10 13 1.41x10 14
2’361’183’241’434’820’000’000 bacterial from 1 original are replicated in 24 hours!!! This number is otherwise known as 2 sextrillion! Mass of one bacterium is around 665x grams ( grams) This means, with an infinite amount of energy and no bacteria dying potentially one bacteria could replicate to form 1’570’186 kilograms of bacteria in 24 hours! Bacterial Reproduction
Disease-causing organisms Organisms that cause disease are called pathogens. bacteriafungi protozoa virus What are the four major types of pathogen?
A disease is any condition where the body isn’t working as it should – this could be caused by a malfunction in the body (as with diabetes) or it could be caused by a pathogen (a microbe that causes disease) Pathogens are micro-organisms that cause infectious disease: bacteria and viruses are the main pathogens What diseases are spread by bacteria / viruses, and how can their spread be reduced?
Microbes are micro-organisms that can cause diseases, entering the body in a number of ways: - Eyes Genitals Skin Mouth Cuts Nose Ears A number of these places where microbes can enter the body are defended
One easy way to defend the body against illness is by keeping it clean and hygienic as microbes can spread very quickly in unhygienic conditions The spreading of microbes is known as transmission As soon as a virus or bacterium enters the body, we are termed infected (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
Measuring cylinder and water represents the body and food colouring represents toxins produced by the bacteria. Using your model build up the toxin level and decide when the toxin level is high enough to produce a disease. How good is this model? What are its limitations? Toxins model
Toxin Levels Presence of microbes Person is infected - microbe levels are low and the toxin levels are low Person is well - microbe levels are very low and the toxin levels are very low Person is ill and diseased - microbe levels are high and the toxin levels are high
When a microbe enters the body it begins releasing 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 The microbes may be able to reproduce, with more microbes increasing the levels of toxins The bodies normal state of ‘well being’ is affected We are said to be ‘diseased’
13 Engage British diplomat Dylan Farrell relaxes on a beach in Brazil. Sorry to disturb you sir...
Good morning Mr Farrell. We have a disease outbreak in the Brazilian rainforest. It’s confined to one village so far, but 90% of the villagers died last week. If it spreads to the rest of the world you can imagine the consequences. Find out what we’re dealing with. 14 Engage
I’m Dr Evans, head consultant here at the microbiology unit. You’ve arrived at a bad time. It’s your first day at your new workplace, the Health Protection Agency (HPA). 15 Explore
We’re expecting some data about a deadly pathogen. 16 Explore The British Diplomatic Service have asked us to identify it.
BacteriaViruses 1/1000 th mm in size1/1’000’000 th mm in size Living (some are harmless) Genetic information stored within a protein coat Reproduce quicklyReplicate quickly within host cell Affected by antibioticsNot affected by antibiotics protein coat genes Distinguishing features not a cell. They invade cells and make them produce 1000s of these particles. Distinguishing features no nucleus no mitochondria has a cell wall. Some species have flagella that let them move. cell membrane genes cell wall cytoplasm
Bacteria are microscopic organisms – they come in many shapes and sizes, but even the largest are only 10 micrometres long (10 millionths of a metre) Bacteria are living cells and, in favourable conditions, can multiply rapidly – once inside the body, they release poisons or toxins that make us feel ill Diseases caused by bacteria include: - ◦ Food poisoning ◦ Cholera ◦ Typhoid ◦ Whooping cough ◦ Gonorrhoea (STI)
Viruses are significantly smaller than the smallest bacterium (among the smallest organisms known) Viruses consist of a fragment of genetic material inside a protective protein coat Viruses can only reproduce inside host cells, and they damage the cell when they do this – if a virus can get inside a cell it can take it over and make hundreds of thousands of copies of itself Eventually the virus copies fill the whole host cell and burst it open – the viruses are then passed out in the bloodstream, the airways, or by other routes
Diseases caused by viruses include: - ◦ Influenza (flu) ◦ Colds ◦ Measles ◦ Mumps ◦ Rubella ◦ Chicken pox ◦ AIDS
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. human body cell) Virus
The virus not only infects the body – it also infects the body cells Approach – the virus approaches the cell Attachment – the virus secures itself to the host cell surface
Insertion – the virus injects its genetic material through the injection tube and into the host cell Replication – the genetic material makes multiple copies of itself
It is at this stage that the viruses within the host cell can remain dormant (virus remains within the cell without killing it or breaking out) – in some viruses, such as HIV, this period can last a number of years Assembly – new viruses are assembled using chemicals from the host cell (the original virus dies and breaks down)
The host cell splits open (cell lysis) and dies and viruses escape and release toxins Each virus will then start another round of replication… Virus Toxin
Micro-organism Examples