Micro-Organisms Chapter 20

Micro-Organisms Micro-organisms are very small organisms. Most are to small to see with the naked eye and we need a microscope. Micro-organisms are found almost everywhere air, water, our skin and our gut.

Micro-organisms There are 3 types of micro-organism Viruses Bacteria Fungi

Viruses

Viruses Viruses are the smallest of the micro-organisms. They cannot be seen with a microscope. Viruses are a chemical surrounded by a protein coat. Viruses do not feed, respire, grow or move they only reproduce.

Viruses

Viruses Viruses only reproduce by invading living cells, which they take over and kill. Therefore all viruses are harmful and cause disease to plants and animals. Viruses are parasites.

Illness caused by viruses http://i.ehow.com/images/GlobalPhoto/Articles/2041461/cold-sore-crop_Full.jpg Cold sore Flu Chicken pox AIDS Measles http://cache.eb.com/eb/image?id=82674&rendTypeId=4 Activity: Ask the kids how many have had each of the diseases and get them to quickly jot down how they thought they were cured. ask a few students about each type of virus induced illness and how they thought they were cured. They will probably all say that they took antibiotics. Explain that antibiotics only have effect on bacterial infections not viral infections and they there are VERY few medicines that will kill viruses. interesting facts: Cold sores: once you have the virus it stays with you for the rest of your life however you wont have a cold sore for the rest of your life but only in times where your body is run down the virus has an advantage over your bodies weakened defences and attacks. Chicken pox you can only get chicken pox once in your life because your body remembers the virus when it enters again and really quickly makes enormous amounts of fighter cells that stop the virus in its tracks before it takes hold . (however people have gotten it twice-- if the virus mutates /changes in any small way and enters your body again it wont be recognised and will attack before the body has time to respond)

Bacteria http://www.bact.wisc.edu/themicrobialworld/C.bot.Spores.jpg

Bacteria Bacteria are simple living cells. Bacteria feed, move, respire and reproduce. Bacteria live almost everywhere. Most bacteria are harmless they even do us good. Other bacteria is harmful and causes disease.

Benefits of Bacteria Soil Nutrients – Soil bacteria decompose the remains of dead plants and animals, this releases nutrients back into the soil. Decay of wastes - Bacteria are used in sewage treatment to break down wastes and make them harmless. Cheese and yogurt - bacteria are used in the making of cheese and yogurt.

Benefits of Bacteria Silage – Bacteria break down grass into silage which is used for feeding cattle.

Harmful Effects of Bacteria Disease – bacteria causes diseases such as food poisoning, pneumonia, meningitis and appendicitis. Food spoilage – Tooth Decay –

Bread mould (long threads) Mushrooms (large structures) Fungi 3 Types Yeast (single cell) Bread mould (long threads) Mushrooms (large structures)

Fungi Most fungi live on dead organisms bread and fruit Some fungi are parasites and cause disease.

Benefits of Fungi Some large fungi are edible (Food) Brewing – Yeast is used to make alcohol. Baking – Yeast is added to dough in baking. Antibiotics – The fungus penicillium is used to make penicillin.

Harmful effects of Fungi Disease – some fungi cause disease e.g. athletes foot and ringworm. Food Spoilage – some fungi cause food to spoil e.g. bread mould. Poisonous – Some fungi are poisonous i.e. certain toadstools.

Soil Micro-organisms Some micro-organisms break down the dead remains of plants and animals and release nutrients back into the soil. These are known as decomposers.

Biotechnology Biotechnology involves using living things like micro-organisms to make substances useful to humans. Examples Industry: Yeast in baking and brewing. Bacteria in cheese and yoghurt. Examples in medicine: Bacteria to make insulin Penicillium to make penicillin.