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Microbes and disease. What are microbes?. What are microbes?. Microbes are very small living things and are sometimes called micro-organisms. Microbes are so tiny that they cannot be seen with the naked eye. They can only be seen using a microscope.
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What are microbes? Microbes are very small living things and are sometimes called micro-organisms. Microbes are so tiny that they cannot be seen with the naked eye. They can only be seen using a microscope. How many different microbes can you name?
Different types of microbes There are three types of microbes: bacteria viruses fungi
Bacteria fact file Microbe: Bacteria (e.g. salmonella and streptococcus) Size: 1/1000 mm Shape: Bacteria can be spherical, rod-shaped or comma-shaped. Structure: Bacteria are single-celled organisms. Their genetic material is not contained within a nucleus. Some cause disease, but many are useful. Reproduction: Bacteria reproduce very quickly. Two can very quickly become four, then eight and so on.
Virus fact file Microbe: Virus (e.g. flu virus and HIV) Size: 1/1,000,000 mm Shape: Viruses have regular and geometric shapes. Structure: A virus is a simple organism that does not display all the characteristics of a living thing.It is made up of a protein coating and some genetic material. Reproduction: Viruses can only grow and reproduce within other living things. Viruses change and adapt to their environment very quickly.
Fungi fact file Microbe: Fungi (e.g. penicillium and yeast) Size: Some fungi can actually be seen with the naked eye, others are slightly bigger than bacterial cells. Shape: Fungi come in many different shapes. Structure: Fungi have the most complex structures of all the microbes. They feed off other living things.
Using bacteria and fungi Microbes have many uses that are based on the fact that they can be grown. Bacteria grow in milk to make it ‘go off’. This type of bacterial growth is used to make milk into yoghurt. Cheese is also produced using certain strains of bacteria. Fungi can also be used to make food. The meat substitute Quorn™ is a protein produced using fungi.
+ ( energy) carbon dioxide + + glucose oxygen water Using yeast Yeastis a type of fungus and carries out respiration. The respiration of this microbe can be used in different ways in baking bread and in brewing. The aerobic respiration of yeast is used to make bread rise. Yeast uses the sugar in bread dough to carry out aerobic respiration: What gas produced by the aerobic respiration of yeast causes bread to rise?
+ ( energy) carbon dioxide + glucose ethanol Using yeast The anaerobic respiration of yeast is used to make beer and wine. In this case, the yeast respires without oxygen and produces alcohol (ethanol). This process is known as fermentation. Yeast converts the sugar into alcohol by anaerobic respiration:
bacteria virus fungi food poisoning influenza (flu) fungal sinusitis sore throats mumps athlete’s foot onychomycosis (causes discoloured toe nails) tuberculosis (TB) chickenpox tetanus smallpox cholera polio typhoid HIV / AIDS bacterial meningitis viral meningitis Microbes can cause disease The diseases caused by microbes, and their severity, depend on the type of microbe:
How do microbes enter the body? Microbes can enter the body in many different places: eyes ears nose mouth genitals cuts skin How do the diseases caused by microbes spread?
Defences against disease Harmful microbes can cause disease by damaging body cells. Once microbes have entered the body, it’s important that they are removed as quickly as possible to reduce damage. The body’s immune system uses specialized cells called white blood cells to identify and destroy the microbes. How does the body try to stop harmful microbes from entering?
What do white blood cells do? If harmful microbes enter the body the immune system produces white blood cells to help defend it from microbes. bacteria antigen Some white blood cells can destroy microbes by engulfing them. white blood cell Some white blood cells are able to produce chemicals called antibodies. These pair with matching antigens on the surfaces of microbes and so help the white blood cells to engulf microbes.
Preventing the spread of disease There are several methods that can help reduce the spread of disease: • disinfecting surfaces • disinfecting skin using antiseptics • sterilizing equipment • using food preservatives in food • personal hygiene. The spread of disease can also be reduced by vaccinating the population and using antibiotics.
What are antibiotics? Antibiotics are chemicals used to treat bacterial infections.These chemicals kill or stop the growth of bacteria. However, some types of bacteria are no longer affected by certain antibiotics – this is called antibiotic resistance. This can be a problem as without effective antibiotics some people might not be able to fight the infection themselves.
What are vaccines? Vaccines can protect people from diseases, such as measles. Vaccines contain dead or weakened strains of the harmful microbe that causes the disease. This stimulates the immune system. If the person comes into contact with the microbe again the immune system can destroy it quickly and effectively. Why is it important that everyone is vaccinated?
