Transcript Micro-organisms - Noadswood Science

Friday, April 1, 2016
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To understand how micro-organisms cause illness
Who is diseased???
1 bacterium divides every 20mins, how many
will there be after 16hrs?
281, 474, 976, 710, 656
Bacterial Reproduction
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1
2
4
8
16
32
64
128
256
512
1024
2048
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4096
8192
16384
32768
65536
131072
262144
524288
1048576
2097152
4194304
8388608
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16777216
33554432
67108864
1.34x108
2.68x108
5.37x108
1.07x109
2.15x109
4.29x109
8.59x109
1.72x1010
3.44x1010
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6.87x1010
1.37x1011
2.75x1011
5.5x1011
1.1x1012
2.2x1012
4.4x1012
8.8x1012
1.76x1013
3.52x1013
7.04x1013
1.41x1014
Bacterial Reproduction
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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 665x10-15 grams
(0.000000000000665 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!
Disease-causing organisms
Organisms that cause disease are called pathogens.
What are the four major types of pathogen?
bacteria
fungi
protozoa
virus
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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?
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Microbes are micro-organisms that can cause diseases,
entering the body in a number of ways: A number of these
places where microbes
can enter the body are
defended
Eyes
Ears
Nose
Mouth
Skin
Cuts
Genitals
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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
Toxins model
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?
Person is well microbe levels are
very low and the
toxin levels are
very low
Person is infected
- microbe levels
are low and the
toxin levels are
low
Person is ill and
diseased microbe levels are
high and the toxin
levels are high
Toxin Levels
Presence of microbes
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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
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The microbes may be able to reproduce, with more microbes
increasing the levels of toxins
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The bodies normal state of ‘well being’ is affected
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We are said to be ‘diseased’
British diplomat Dylan
Farrell relaxes on a
beach in Brazil.
Sorry to disturb
you sir...
Engage
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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.
Engage
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It’s your first day at your new workplace,
the Health Protection Agency (HPA).
I’m Dr Evans, head consultant
here at the microbiology unit.
You’ve arrived at a bad time.
Explore
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We’re expecting
some data about a
deadly pathogen.
The British
Diplomatic
Service have
asked us to
identify it.
Explore
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Bacteria
cell wall
cytoplasm
Viruses
genes
protein coat
genes
cell
membrane
Distinguishing
features
no nucleus
no mitochondria
has a cell wall.
Some species
have flagella
that let them
move.
Distinguishing features
not a cell.
They invade
cells and make
them produce
1000s of these
particles.
1/1000th mm in size
1/1’000’000th mm in size
Living (some are harmless)
Genetic information stored within
a protein coat
Reproduce quickly
Replicate quickly within host cell
Affected by antibiotics
Not affected by antibiotics
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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)
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Viruses are significantly smaller than the smallest bacterium
(among the smallest organisms known)
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Viruses consist of a fragment of genetic material inside a
protective protein coat
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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
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Diseases caused by viruses include: ◦ Influenza (flu)
◦ Colds
◦ Measles
◦ Mumps
◦ Rubella
◦ Chicken pox
◦ AIDS
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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
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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
Assembly – new viruses are
assembled using chemicals
from the host cell (the
original virus dies and
breaks down)
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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
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The host cell splits open (cell lysis) and dies and viruses
escape and release toxins
Each virus will then start another round of replication…
Toxin
Virus
Micro-organism Examples