What are micro-organisms?

Microbes

– Microbes are single celled organisms

– Too small to be seen with the naked eye

– They are found practically EVERYWHERE on earth

– Also commonly known as bugs, germs and microbes

– Generally divided into 3 different groups

• Bacteria

• Virus

• Fungi

Bacteria– Obtain nutrients from their environments in order to live. In some cases that

environment is a human body

– Most are helpful or harmless. But some cause disease

– Bacteria can reproduce outside of the body or within the body as they cause

infections

– Some bacteria are good for our bodies:

• Good bacteria live in our intestines and help us use the nutrients in the food we

eat and make waste from what's left over.

– They are found everywhere on earth, in the ocean, in rocks, in volcanoes, in

our bodies and in the soil

Bacterial Structure

Chromosome: DNA material of the cell

Cell wall: Composed of peptidoglycan the cell wall maintains the overall shape of a bacterial cell

Cell membrane: Lining the inside of the cell wall it provides a boundary for the contents of the cell and a barrier to substances entering and leaving.

Cytoplasm: Describes the inside of the cell and the contents

ChromosomeCell Membrane

CytoplasmCell wall

Bacterial Shapes

There are 3 different shapes of bacteria

Spirals(Campylobacter)

Rods(Lactobacillus)

Balls or cocci(Staphylococcus)

Viruses– Viruses are even smaller than bacteria and can sometimes live INSIDE

bacteria

– Most viruses make us ill

– Diseases like CHICKENPOX and the FLU are caused by viruses.

– Viruses are easily spread from one person to another.

– Viruses cannot reproduce by themselves. They infect other cells and take

over their reproductive machinery in order to reproduce.

– They multiply inside the ‘host’ cell and when they have used all the cells

reproductive machinery, thousands viral cells burst out of the cell. The host

cell is completely destroyed.

Viral StructureEnvelope• Double lipid layer holding the

cells genetic material.

GlycoproteinsThese serve 2 purposes • Anchor the virus to the host cell. • Transport genetic material from

the virus to the host cell. Nucleic acid• Either DNA or RNA material, but

virus cells rarely contain both. Most viral cells contain RNA material.

Complex (Bacteriophage – a virus which infects bacteria)

Envelope

Nucleic acid

Glycoproteins

Viral Shapes

Icosahedral(Influenza)

Complex(Bacteriophage – a virus which infects

bacteria)

Helical(Tobacco mosaic virus)

There are 3 different shapes of Virus

Fungi– The largest and most versatile of all microbes

– Large plant like structures which lack chlorophyll

– Need to absorb nutrients from whatever they are growing on

– Fungi can be very helpful and humans have used them in

– The food industry - brewing beer, making bread rise

– Medicine – making antibiotics

– They can also be harmful if they steal nutrients from another living

organism. Examples include, mould on bread and athletes foot

which is caused by a group of fungi known as dermatophytes

– Fungi can be found in the air, on plants and in water

Fungal Structure

Sporangia: Spore producing body. Sporangiophore:Filamentous stalk on which the sporangium forms.Rhizoids: The sub-surface hyphae are specialized for food

absorption.

Sporangiophore

Sporangia

Rhizoids