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