In This Section We Will Be Studying The Following Topics: MICROBES In This Section We Will Be Studying The Following Topics: The different types of micro-organisms, their size and structure. Helpful and harmful micro-organisms. Disease and defences of the body. Antibiotics and the problems of using them. The way diseases spread and how to stop them. Immunity and immunisation. Vaccinations and vaccination programmes.

There are three different types of microbe: MICROBES There are three different types of microbe: BACTERIA. VIRUS. FUNGI. Here are three examples you might have heard of: Salmonella bacterium. Rabies virus. Field mushroom. This causes food poisoning. This can affect humans and dogs. We can eat these as part of a balanced diet.

MICROBES Viruses then bacteria then fungi. Microbes are the oldest form of life on Earth. Some types have existed for billions of years. Microbes live in the water you drink, the food you eat and the air you breathe. About 95% of all microbes are helpful. In order of size (smallest to largest): Viruses then bacteria then fungi.

BACTERIA ‘Microbe’ is used as a shorter version of the word micro-organism. You may hear micro-organisms being called ‘germs’ but the term is not scientific. CELL WALL CELL MEMBRANE LOOP OF GENETIC INFORMATION CYTOPLASM Bacteria Most bacteria are about one thousandth of a mm in length. About 100 times smaller than an animal cell. They can multiply very quickly. They can release poisons that attack your cells.

KILLING BACTERIA Antibiotics can be used to help us ‘fight off’ a BACTERIAL INFECTION. They do not work against VIRUSES. Some bacteria are becoming RESISTANT to antibiotics. Antibiotics are only SPECIFIC FOR ONE DISEASE. They take time to work as they support the work of the white blood cells. We can also use cleaning products that have antibacterial agents in them to control the spread of disease. To stop bacteria spreading it is very important to keep operating theatres STERILE. The instruments and clothing are clean. They are only opened in an ASEPTIC area. They are never reused on a different patient until they have been STERILISED.

MICROBES VIRUSES Strand of genetic material Protein coat Viruses are tiny - they are only about one millionth of one mm in length. They can only multiply if they take over a cell. They make millions of copies of themselves. They are a strand of genetic material in a protein shell. The common cold is caused by a virus.

MICROBES Fungi hyphae Fungi can be very small or very large. Fungi do not make their own food by photosynthesis so they are not plants. Some species of fungi get their nutrition by breaking down the remains of dead plants or animals. Two fungal diseases that affect humans are athlete's foot and ringworm. Fungi Fungi can be very small or very large. Yeast is a fungi and it can only be seen with a microscope.. We do not need a microscope to see a toadstool! They have cells with a nucleus not just a piece of genetic material. They have cell walls. They are joined together in long strands called hyphae. They can grow quickly and release poisons that attack your cells. We use lots of fungi in antibiotics and the food industry.

Which statements are true and which are false? TRUE OR FALSE? Which statements are true and which are false? Bacteria are 100 times smaller than an animal cell. Viruses can reproduce and grow outside of other living things. Viruses cause food poisoning, sore throats etc . Viruses are 100,000 times smaller than an animal cell. Bacteria are made up of a protein coat which surrounds their genetic material. Fungi are the largest of the 3 micro-organisms. We eat some types of fungi e.g. mushrooms. Some bacteria are used in food production e.g. yoghurts. True False False True False True True True

OUR BODY The human body has some natural defence mechanisms to protect it from microbes. The white blood cells are particularly important in fighting infection. There are two types of white blood cells. Lymphocytes produce antibodies to destroy bacteria. Lymphocyte Phagocyte. The second type are phagocytes that surround and destroy bacteria.

ANTIBODIES White blood cells called LYMPHOCYTES make ANTIBODIES. They can work in three ways. White blood cells have a nucleus ANTIBODIES GET RELEASED INTO THE PLASMA They can stick to invaders and clump them together. These are then destroyed by the phagocytes. They can surround an invader and make it harmless. They can attack invaders, push into them and destroy them.

DISEASES The name given to an organism that causes a disease is a PATHOGEN. There are a small number of diseases that are not caused by bacteria, viruses or fungi. These are caused by another small micro-organism called a PROTOZOAN. Protozoa are a single cell that includes a nucleus. The come in many shapes and sizes. They can be parasitic; needing to live inside another organism. Drugs that may destroy the protozoan may also destroy human cells. Protozoan infections include amoebic dysentery, malaria, and African sleeping sickness.

DISEASES FUNGI BACTERIA VIRUSES MEASLES TYPHOID CHICKEN POX Here are 3 groups of diseases. One group is caused by bacteria, one by fungi and one by viruses. Which is which? MEASLES CHICKEN POX INFLUENZA HIV/AIDS TYPHOID MENINGITIS WHOOPING COUGH ATHLETE’S FOOT THRUSH FUNGI BACTERIA VIRUSES

Think about this…… how hard would this be in a very hot country? AVOIDING DISEASES Wash yourself and your clothes only in clean water. Only clean cuts or entrances into the body with clean water. Water Be careful on holiday -don’t swim in places where the water is of poor quality. Drink clean water. Don’t share liquid containers. This comes out of the tap in Britain. You can buy it in bottles. Cups and bottles should be washed out. Think about this…… how hard would this be in a very hot country?

AVOIDING DISEASES Air Don’t cough and sneeze over others. Avoid spreading your cough or cold. Use a tissue. In hospitals people with disease are often BARRIER NURSED. What does this mean? Air Don’t let mould or fungal spores spread around the places people live in. Use insect repellents to stop the spread of disease. Keep the air clean in food preparation areas. Eat food straight away outdoors.

IMMUNISATION In BRITAIN we are able to have an injection called a Vaccination. A Vaccine is a form of the disease that is not fully active. The vaccine causes our white blood cells to make antibodies as if they were fighting the real virus. When the body does come into contact with a ‘live’ form of the virus the antibodies can be made more quickly. Some vaccinations need to have Boosters over time as the effect wears off. You are then Immune to the disease.

IMMUNITY Some people are born with immunity. What is a vaccine? It could be: Dead forms of the micro organism. A very weak form of the micro organism. Small parts of the micro organism. We are injected with a small amount of the disease to stimulate our white blood cells to produce antibodies for that disease. If you then come into contact with the disease you already have IMMUNITY. Some people are born with immunity. This has been passed on by their parents. It is why some people do not catch new diseases and can survive. These people can help in the research of disease prevention.

VACCINATION Correct order: 1, 4, 2, 5 and 3. Microbes enter the body. Put the following statements into the correct order to show what happens when microbes invade your body: Microbes enter the body. Microbes multiply. You feel ill. Your body responds quickly and the microbe is destroyed before it has chance to multiply and cause illness. Your body responds slowly. Your body produces antibodies and white blood cells to destroy invading microbes. Once the microbe is destroyed the symptoms disappear. Correct order: 1, 4, 2, 5 and 3.

NATURAL DEFENCES Tears – Contain an enzyme Gut – Look at the diagram below and try to explain how each part of the body protects us from microbial attack: Tears – Contain an enzyme called lysozyme which can break down bacterial cell walls. Gut – The gut contains friendly bacteria to prevent digestive problems. Mucus - This is found in the nose and air passages. It is a sticky liquid that can trap dirt and dust. Earwax – Protects the ear canal by trapping dirt and dust. Skin – This acts as a barrier and is slightly acidic. Stomach acid – This is pH 2 hydrochloric acid that can destroy bacteria.

MICROBIOLOGY Microbes are used in industry to do jobs for us. YEAST is used to make BREAD and ALCOHOL, especially beer and lager. It makes the bubbles in the beer. As the yeast respires it produces bubbles of carbon dioxide that makes the bread rise. FUNGI are used in the CHEESE industry to make blue cheeses. YOGHURT is made by adding bacteria to milk. It makes lactic acid. This gives yoghurt its tangy taste.

Match up the disease with the way it is transmitted. DISEASES Match up the disease with the way it is transmitted. This disease can be passed on by sexual intercourse. Chicken pox. This disease is passed on by eating contaminated food. HIV/ AIDS. This disease can be passed on by drinking contaminated water. Hepatitis. Cold and flu. Spread through droplets from coughs and sneezes. Food poisoning. This disease can be transferred via the blood. Typhoid. This disease can be passed on via touch.

ANAGRAMS Looid well tehbc Toncneiif Sirvu Riaceatb Sufung vIonniatacc Unscramble the words Looid well tehbc Toncneiif Sirvu Riaceatb Sufung vIonniatacc Roembic

ANAGRAM ANSWERS White blood cell. Infection. Virus. Bacteria. Fungus. Vaccination. Microbe.

LET’S THINK The statements below are all about Malaria. Malaria is a disease that is transmitted by mosquitoes. When a mosquito bites a human a micro-organism is injected into the person’s bloodstream. Put the statements in order of how important you think they are: Wear a hat at all times when mosquitoes may be around. Have a mosquito net around the bed at night. Wear sunscreen that is factor 15 or higher. Wear insect repellent. Take malaria tablets before your holiday. See a doctor if you think you have been bitten by a mosquito. Keep your arms and legs covered at all times. They bite humans to feed on their blood. Symptoms of malaria are fever and even death.

CHECK YOUR LEARNING! There is a micro-organism that can pass on diseases like sleeping sickness. What is this type of microbe called? Put the following in order of smallest to largest: fungi virus bacteria What does the ear produce to protect it? What does the stomach produce to protect the digestive system? Can antibiotics be used to help us fight a virus? Why do we keep operating theatres clean? How can you immunise someone? Why do you think babies are given injections for measles?

CHECK YOUR LEARNING. ANSWERS They are called protozoans. The order is: virus bacteria fungi The ear produces wax. The stomach produces hydrochloric acid at pH2. Antibiotics cannot be used to ‘fight off’ a virus. We keep theatres very clean because we are making an opening to our bodies. Microbes could easily infect the wound. You can immunise someone by giving them a vaccination. Babies have not met very many microbes and they would have to fight very hard to get rid of an infection. It is better to have antibodies ready to do this. Stay clean, stay healthy.