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Microbes Bacteria are singlecelled organisms Bacteria have the tools to reproduce themselves by themselves They are filled with fluid and may have threadlike structures to move themselves like a tail ID: 739477 Download Presentation


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Bacteria are single-celled organisms. Bacteria have the tools to reproduce themselves, by themselves. They are filled with fluid, and may have threadlike structures to move themselves, like a tail.

Viruses may have a spiny outside layer, called the envelope. Viruses have a core of genetic material, but no way to reproduce it on their own.

Viruses cannot reproduce on their own. They infect cells and take over their reproductive machinery to reproduce.Slide5


Some different shapes of bacteria

The good the bad and the ugly!Slide6

Structure of bacteria

Flagellum (Tail for movement)

Cell wall

Cell membrane

Slimy capsule

Strand of DNA



bacteria help you digest foodSlide8

Bacteria help to

break down

faeces in

sewage works.Slide9

Bad bacteria in the mouth cause teeth to rot.

Mouth bacteriaSlide10

MRSA- the bacterial superbug!


ethicillin Resistant




ureusMethicillin (anantibiotic) WON’T Work to cure this infection!Slide11

Structure of virusesSlide12

How viruses replicate inside cellsSlide13

Examples of viruses

A T4 bacteriophage. This infects only bacterial cells, in this case only E. coli

The HIV virus. Slide14


lu virusSlide15


Fungi are organisms that produce spores

and come in the form of moulds, yeasts,

mushrooms and toadstools.

They also help things to rot and breakdown

which is an essential process in the cycle of life.Slide16

Examples of fungi

Mould growing

on a

bread bun

There can be good forms of

fungus (used to make


Mould and fungus causes things to breakdownSlide18


foot – a bad fungusSlide19


thrush – another fungus

Thrush yeast cellsSlide20

But not all viruses, bacteria or fungi caus

e disease



is something that causes diseaseSlide21


How They Get Around

Bacteria have many different shapes. Some have 'tails' (called flagella) that let them swim. They rotate their flagella like tiny propellers to move themselves through liquids.

Other bacteria make slime so they can ooze over surfaces like slugs.

Others stay almost in the same spot.

What They Look Like

There are thousands of types of bacteria. Some are rod-shaped; others are shaped like little balls. Some are spirals.You could fit 1000 of them across 1 mm!Slide22

Bacteria Basics

Many of us know bacteria only as


, invisible creatures that can invade our bodies and make us ill. They live in, on and around us all the time.

Not everyone knows that bacteria also do lots of good things, like break down dead leaves and other rubbish, and make oxygen.We can even use bacteria, making them work for us!These bacteria turn milk into yoghurt!These bacteria give you a sore throat!Slide23

Bacteria grow where?

Bacteria can be found almost everywhere!

Bacteria live on or in just about every material and place on Earth, from soil to water to air, and from your body to the North Pole to the Sahara desert.

Many types can survive below freezing temperature (0


, and some types can survive above boiling point (100

°C).This picture was taken with a very powerful microscope. This bacterium lives in soil, and moves through soil water using its flagella.Slide24

Do bacteria on you always make you ill?

Lots of them live on you, but don

t worry, almost all of them are good for you! Each square centimetre of your skin has about 100,000 bacteria on it.

This picture shows bacteria on human skin. (They aren

t really bright pink; they’ve been coloured in pink so you can see them better.)That big tree trunk in the picture is actually a human hair. So now you can see how small bacteria are!Slide25

How old are bacteria?

How Long They’ve Been Around

Like dinosaurs, bacteria left behind fossils. The big difference is that it takes a microscope to see them. And they are older.

Bacteria were the earliest forms of life on Earth. They first appeared about 4 billion years ago, and for the next

2 billion

years they were the only life on Earth!

Bacteria fossil, 3 million years oldSlide26

What have they ever done for us?

Without Bacteria, We Could Never Have Existed!

Earth was a poisonous place back in the early days. There was no oxygen around, so we and most other animals and plants could not have existed.

Then some types of bacteria started making oxygen using the energy from sunlight – they had invented


! Once plenty of oxygen had built up in the atmosphere, it became possible for plants and animals to develop. So bacteria paved the way for us! Thank you, bacteria!

Earth might have looked like this in the early days.Slide27

Different types of bacteria eat different foods. Some eat sugar and starch; others eat sulphur, or even iron!

Others use sunlight to make their own food, like plants do.


This twisty-looking bacterium eats iron for its dinner! Weird!Slide28

There are 100 trillion (100,000,000,000,000) bacteria – weighing

2 ½ kilos altogether - happily living in your intestines.

That's ten times more bacteria than there are cells in your body.More bacteria than the number of stars in our galaxy, more bacteria than the number of humans who have ever lived...

Bacteria in you

This is one of the types of

good’ bacteria that live in people’s intestines.Slide29


Virus Basics

Viruses are the


type of microbe, even smaller than bacteria.

Viruses are really the bad guys of the microbe world. They don

’t do anything that we would call good. (Only in the last few years have scientists come up with ways of making viruses do useful things for us…)Viruses are strange things that are somehow in between being alive and not alive. If they're floating around in the air or sitting on a doorknob, they do absolutely nothing. They're about as alive as a rock. But if they come into contact with a suitable plant or animal cell, they spring into action. They infect and take over the cell like pirates hijacking a ship.As a virus cannot reproduce without using another creatures’ cells to help it, some people are not convinced that viruses are really living things. This virus gives you flu!This virus gives you a cold!Slide30


How They Get Around

Unlike bacteria, viruses can

t move themselves around.

But once a virus has got into another creature

’s cell and used it to make new copies of itself, the cell bursts, and the new virus copies get shot off into the cells next door. What They Look LikeThere are thousands of types of virus that come in many shapes.Many have geometric shapes, like cut diamonds. Others are shaped like spiky eggs, skinny sticks or pieces of looped string. Some are more complicated and look like tiny spaceship landing pods.Viruses don’t have a nucleus. Their DNA (genes) just floats around inside them. They aren’t really even proper cells.Draw this simple one:This is a picture taken with a microscope, showing a virus attacking a cell. Don’t draw it – it’s too complicated.Slide31


Where They

re Found

Viruses can be found almost everywhere! They

re all over the planet, in soil, water and air, just waiting around for cells to infect.Viruses can infect every living thing. However, they tend to be picky about what type of cells they infect. Plant viruses do not infect animal cells, for example.When you have a cold and you sneeze, the cold virus is in the drops that shoot out of your nose and mouth! If it lands on someone else, it gets to work on them……so use a tissue!This virus hangs around in soil, and infects wheat.Slide32


Read at your own risk – this may shock you!

Viruses are Really, Really Tiny

Even compared with bacteria (and your own cells), viruses are very small.

Viruses don

t just attack cells of humans, other animals, and plants. They even attack bacteria!If you lined up a million of them, they would only cover 1 mm in length!Slide33



Fungi Basics

Yeasts are single-celled fungi, so they are microbes. So is mould.

Fungi are usually bigger than bacteria.

If there is just one of them, we call it a

fungus. Fungi are more like animals than plants. For one thing, fungi cannot make their own food like plants do, but instead they eat other organisms, as animals do. With fungi, there are good guys and there are bad guys. Some make our food go mouldy, and some cause diseases. But they also break down dead plants and animals, keeping the world tidier.We use some fungi to do things for us, like make bread rise and brew beer. These mushrooms are fungi, but they’re big and they’ve got loads of cells, so they’re not microbes. We’ll ignore these for now.Yeast cellsSlide34



How They Get Around

Individual fungi don’t move around.

But they can spread by making tiny


(a bit like seeds) that are carried by wind and rain and grow into new fungus cells when they land.Some fungi, such as moulds, make long threads of cells called hyphae. These threads are what make mould look fuzzy. Moulds can spread by growing and extending their hyphae.What They Look LikeFungi come in a variety of shapes and sizes and different types. They can range from single cells to enormous chains of cells that can stretch for miles. Yeast cells look round or oval under a microscope. They're bigger than bacteria, but still too small for your eyes to see them individually. Draw and label this fungus cellSlide35



Where They

re Found

Fungi usually grow best in places that are slightly acidic. Fungi live in the soil and on your body, in your house and on plants and animals, in freshwater and seawater.

A single teaspoon of soil contains about 120,000 fungus cells!Whoa! The mould on this bread is really out of control!If you ever get athlete’s foot (a skin complaint that gives you itchy feet), then you’ve got a fungus growing on you! (Don’t worry, it’s not serious, and you can buy an ointment that kills the fungus.) The fungus likes moisture, so drying between your toes helps to keep it away.Slide36



Read at your own risk – this may shock you!

The Humongous Fungus (definitely


a microbe!)Fungi range in size from the microbe we call yeast to the largest known living organism on Earth — a 3.5-mile-wide fungus.Nicknamed ‘the humongous fungus’, this honey mushroom covers 2,200 acres in the state of Oregon, in the USA.The only above-ground signs of the humongous fungus are patches of dead trees (which the fungus has killed by eating them), and the mushrooms (the ‘fruits’ of the fungus) that form at the base of infected trees.It started out 2,400 years ago as a single spore invisible to the naked eye. It slowly grew to immense size by growing long threads of cells called hyphae, under the ground.Threads called hyphae grow and spread underground

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