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Thursday, May 9, 2013 ISN page 138 Bacteria The Bacterial Cell • Bacteria are prokaryotes – their genetic material is not contained within a nucleus. • Bacteria have a cell wall on the outside and cytoplasm on the inside. The cells genetic material and ribosomes are found in the cytoplasm. • Some bacteria have a flagellum that helps it move. If not, the cell moves by the air, water, or by other objects. • Most bacteria are spherical, rod like, or spiral. • They range in size, most are about 0.5-1 micrometer (one-millionth of a meter) Obtaining Food & Energy • Some bacteria are autotrophs – either using the sun or from chemical substances in their environment. • Bacteria that are heterotrophs consume other organisms or food other organisms make. • From meat to milk to decaying leaves. • Many bacteria go through respiration. But some types of bacteria die in the presence of oxygen! Reproduction • When bacteria have plenty of food, the right temperature, and other suitable conditions, they thrive and reproduce frequently. – Some bacteria can reproduce every 20 minutes. • Some bacteria reproduce by a process called binary fission. – One parent creates 2 offspring with identical genetic material. • Some bacteria reproduce by two parent cells combining their genetic material to create a new offspring. – The offspring is different form both parent cells. The Role of Bacteria in Nature • Oxygen Production – Scientists believe autotrophic bacteria were responsible for adding oxygen to the earth’s atmosphere billions of years ago. • Food Production – Bacteria helps create yogurt, cheeses & sour cream. It can also cause food to spoil. • Environmental Recycling – Some bacteria are decomposers in the soil. • Environmental Clean Up – They can help clean up oil spills and gas leaks. • Heath & Medicine – Many of the bacteria in your body keep you healthy. • Helps you digest food & makes vitamins LEFT PAGE: Bacteria Questions Q1: A friend states that all bacteria are harmful to people. List three reasons why this statement is not true. Q2: How might bacteria contribute to a pea plant growing successfully?