chapter 18.2: bacteria
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Chapter 18.2: Bacteria. 1. Prokaryotes are unicellular organisms that do not have a nucleus or membrane-bound organelles. 2. They are classified into two kingdoms-- archaebacteria and eubacteria . - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 18.2: Bacteria
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1. Prokaryotes are unicellular organisms that do not have a nucleus
or membrane-bound organelles.
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2. They are classified into two kingdoms-- archaebacteria and
eubacteria.
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3. There are three types of archaebacteria that live mainly in extreme habitats where there is usually no free oxygen available.
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4. One type of archaebacterium lives in oxygen-free environments and
produce methane gas.
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5. A second type lives only in water with high concentrations of salt.
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6. The third type lives in the hot, acidic
water of sulfur
springs.
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7. Eubacteria, the other kingdom of prokaryotes, include those prokaryotes
that live in places more hospitable than archaebacteria inhabit.
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8. Some bacteria are parasites, obtaining their nutrients from living
organisms
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9. Others are saprobes--organisms that feed on dead organisms or
organic wastes.
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10. Some eubacteria live in places with sunlight because they need light to
make the organic molecules that are their food.
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11. Some eubacteria break down and release the energy of inorganic
compounds containing sulfur and nitrogen in the process called
chemosynthesis.
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12. A bacterium consists of a very small cell.
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13. Prokaryotic cells have ribosomes, but they are smaller than those of
eukaryotes.
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14. They also have genes that are located in a single circular
chromosome.
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15. One structure that supports and protects a bacterium is the cell
wall.
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16. Draw, color, and
label Figure
18.10 from the book.
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17. In 1928, Sir Alexander Fleming
accidentally discovered
penicillin, the first
antibiotic--a substance that
destroys bacteria.
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18. Biologists discovered that penicillin can interfere with the ability of some
bacteria to make cell walls.
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19. The three most common shapes of bacteria are spheres called cocci;
rods called bacilli; and spirals called spirilli.
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20. Bacterial cells often grow in characteristic patterns that provide
another way to categorize them.
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21. Diplo- is a prefix that refers to a paired arrangement of cell growth.
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22. The prefix staphlo- describes an arrangement of cells that resemble
grapes.
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23. Strepto- is a prefix that refers to an arrangement of chains of cells.
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24. Bacteria reproduce asexually by a process known as binary fission.
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25. The resulting cells are genetically identical.
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26. Some bacteria
have a form of sexual
reproduction called
conjugation.
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27. During conjugation, one
bacterium transfers its
chromosome to another cell through a
bridgelike structure called a pilus that connects the two
cells.
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28. Conjugation results in a bacterium with a new
genetic composition.
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29. Many bacteria require oxygen for respiration. These bacteria are
called obligate aerobes.
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30. There are other bacteria, called obligate anaerobes, that are killed
by oxygen.
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31. Some bacteria, when faced with unfavorable environmental
conditions, produce endospores.
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32. An endospore is a tiny structure that contains a
bacterium’s DNA, encased by a tough outer
covering that resists drying out,
temperature extremes, and
harsh chemicals.
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33. When environmental conditions improve, the endospore
germinates, or produces a cell that begins to grow and reproduce.
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34. Some bacteria
produce a powerful
and deadly poison, called a
toxin, as they grow.
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35. Disease-causing bacteria are few compared with the number of
harmless and beneficial bacteria on Earth.
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36. Several species of bacteria have enzymes that convert nitrogen gas into ammonia in a
process known as nitrogen fixation. Bacteria are the only organisms that can
perform these chemical changes.
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37. Life could not exist if decomposing bacteria did not break down the organic materials in
dead organisms and wastes, returning nutrients to the environment.
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38. Some foods that you eat would not exist without bacteria.
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39. List three foods that are made using bacteria.
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40. Bacteria also inhabit your intestines and produce vitamins
and enzymes that help digest food.
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41. Some bacteria produce important antibiotics that destroy other types
of bacteria.
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42. Bacteria cause diseases in plants and animals.
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43. Bacterial diseases harm people in two ways. The growth of the bacteria can interfere with the
normal functioning of body tissue, or it can release a toxin that
directly attacks the host.
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44. List three bacterial diseases.