Structure & Function of Cells Living Cells Structure & Function of Cells Mr G Davidson

Cellular Structure Cells are the living units from which all organisms are made. Simple organisms have only one cell and are unicellular, e.g. bacteria. Other organisms have many cells working together and are multicellular, e.g. humans. Tuesday, December 04, 2018 Mr G Davidson

Animal Cell Structure Cell membrane Nucleus Cytoplasm Tuesday, December 04, 2018 Mr G Davidson

Animal Cell Structure Cell Structure Function Nucleus Cytoplasm Controls cell activities and passes on information to the next generation Cytoplasm Site of all biochemical reactions Cell membrane Controls what enters and leaves the cell Tuesday, December 04, 2018 Mr G Davidson

Plant Cell Structure Nucleus Cell wall Cell membrane Cytoplasm Vacuole Chloroplast Cytoplasm Tuesday, December 04, 2018 Mr G Davidson

Plant Cell Structure Cell Structure Function Chloroplast Cell wall As well as the same structures found in animal cells, the following structures are also found in plant cells only. Cell Structure Function Chloroplast Contains chlorophyll which traps light energy to be used in photosynthesis Cell wall Made of cellulose and supports the structure of the cell Vacuole Stores water and solutes as a solution called “cell sap” Tuesday, December 04, 2018 Mr G Davidson

Cellular Structure Cells are too small to be seen with the naked eye. We use a light microscope to study cells. Stains are often used to make certain parts of the cells more visible, e.g. Methylene blue is often used to stain animal cells Iodine solution is often used to stain plant cells. Tuesday, December 04, 2018 Mr G Davidson

Microbial Cells A microbe is a microscopic unicellular organism. Microbes are found almost everywhere that life can exist. Microbes exist in huge numbers. They can usually reproduce very quickly. Tuesday, December 04, 2018 Mr G Davidson

Microbial Cells Some can cause disease and some can cause things to rot (decompose). Others are useful, e.g. bread-making, wine-making, recycling, etc.. There are different types of microbe, e.g. bacteria, yeast, etc. Tuesday, December 04, 2018 Mr G Davidson

Yeast Yeast is a unicellular fungus. Yeast cells are not mobile. Yeast can be used to change sugar into alcohol and carbon dioxide in a process called fermentation. Yeast + Sugar Alcohol + Carbon dioxide Tuesday, December 04, 2018 Mr G Davidson

Uses of Yeast Humans have made use of yeast for thousands of years for such things as: Baking Wine making Brewing Tuesday, December 04, 2018 Mr G Davidson

Baking Alcohol Yeast + + Dough Carbon + dioxide Sugar When the dough is cooked the alcohol evaporates Alcohol Yeast + + Dough Carbon dioxide + Sugar Carbon dioxide makes the dough rise Tuesday, December 04, 2018 Mr G Davidson

Wine Making Alcohol Yeast + + Sugar from Carbon fruits dioxide Alcohol used to make wines & spirits for drinking Alcohol Yeast + Alcohol can also be used as an alternative fuel + Sugar from fruits Carbon dioxide Carbon dioxide is released as a waste product Tuesday, December 04, 2018 Mr G Davidson

Brewing Yeast Alcohol + Malted + barley Carbon + dioxide Hops Alcohol used to make beers Yeast Alcohol Starch in barley changed to sugar + Alcohol can also be used as an alternative fuel Malted barley + Carbon dioxide + Used to add flavour Hops Carbon dioxide is released as a waste product Tuesday, December 04, 2018 Mr G Davidson

Bacteria Bacteria are useful for some things as well, such as making yoghurt. Bacteria feed on a sugar found in milk called lactose. This sugar is converted to lactic acid by the bacteria. It is the lactic acid which turns the milk into yoghurt. Tuesday, December 04, 2018 Mr G Davidson

Antibiotics Antibiotics are substances which prevent the growth of bacteria. Penicillin was the first antibiotic and it was discovered by Alexander Fleming in 1928. He was growing bacteria and discovered that a fungus has contaminated his plates and that no bacteria were growing near the fungus. Tuesday, December 04, 2018 Mr G Davidson

Alexander Fleming Tuesday, December 04, 2018 Mr G Davidson

Antibiotics Bacteria are less sensitive to this antibiotic resistant to this antibiotic “Clear area” indicates no bacterial growth Bacteria Tuesday, December 04, 2018 Mr G Davidson

Antibiotics Many other antibiotics have now been discovered and they are produced by fungi. Bacteria which cannot grow near an antibiotic are said to be sensitive to the antibiotic. Tuesday, December 04, 2018 Mr G Davidson

Antibiotics Bacteria which do grow near an antibiotic are said to be resistant to the antibiotic. A wide range of antibiotics are, therefore, required to combat the wide range of bacteria that exist. There are effectively 2 groups of antibiotics: Narrow-spectrum antibiotics which are useful against a few specific species of bacteria. Wide-spectrum antibiotics which are useful against a wide range of species of bacteria. Tuesday, December 04, 2018 Mr G Davidson