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Bacteria I.All bacteria are Prokaryotes- single celled organisms that lack a nucleus.

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Presentation on theme: "Bacteria I.All bacteria are Prokaryotes- single celled organisms that lack a nucleus."— Presentation transcript:

1 Bacteria I.All bacteria are Prokaryotes- single celled organisms that lack a nucleus.

2 Peptidoglycan Cell Wall Cell membrane Ribosome Pilli DNAFlagellum



5 II. Classifying Prokaryotes- all prokaryotes were once in Kingdom Monera; now divided into 2 kingdoms A. Kingdom Eubacteria 1. Largest group 2. Can live almost anywhere, even in your intestines (ex. E.-coli) 3. Have cell walls 4. Unicellular B. Kingdom Archaeabacteria 1.Live in extreme environments (ex. Methanogens and Halophiles) 2.Have cell walls 3.Unicellular

6 E-coli in human intestines provides vitamin K and some of the B vitamins

7 Dead Sea Archaebacteria- Extreme Environments Halophiles- “Salt Lovers”

8 Archaebacteria- Extreme Environments Methanogens- Live in lots of Methane

9 Archaebacteria- Extreme Environments Thermophiles - Extrme “Temperature Lovers”

10 III. Identifying Prokaryotes- use shape, cell wall chemical structure, movement method of obtaining energy and releasing energy, and growth and reproduction. A.Shape- 3 types 1. Bacilli-rod shaped 2. Cocci- sphere shaped 3. Spirilla- corkscrew shaped

11 Identify the following:

12 B. Cell wall structure- 2 types, identified by Gram staining (used for prescribing antibiotics) 1.Cell wall containing mainly peptidoglycan appear purple = Gram Positive. 2.Cell wall with extra outer layer of lipids appear red = Gram Negative

13 Which of these bacteria are gram positive?

14 C. Movement- some have flagella (long whip-like tail), some glide on slime, some don’t move


16 D. Obtaining Energy 1. Producers-(Autotrophs) make their own food a. Examples: Cyanobacteria – carry out photosynthesis 2.Consumers- (Heterotrophs) most prokaryotes consume food.

17 E. Releasing energy- 3 ways to release energy from food. 1.Aerobes- use cellular respiration, need oxygen 2. Anaerobes- use fermentation, poisoned by oxygen 3. Facultative anaerobes- use fermentation or cellular respiration (can live anywhere)

18 F. Growth and Reproduction 1.Binary fission- asexual reproduction, produces two identical daughters cells, most bacteria do this



21 III. E.Q. What role do bacteria play in nature? A.Producers- capture sun’s energy through photosynthesis, food source for consumers and produce oxygen B. Decomposers- bacteria help recycle nutrients by breaking down dead organisms; they break down complex compounds into simpler ones.

22 C. Nitrogen Fixers- bacteria are the only known organisms that can convert nitrogen into a form that plants are able to use. 1. Some plants (legumes) even have a symbiotic relationship in which bacteria live on their roots and help them absorb nitrogen.

23 D. Foods- Bacteria are used in the processw of making foods such as

24 D. Disease causers- (pathogens) 1.Pathogens cause disease 2 ways. a.Bacteria can break down body tissue- Tuberculosis b. Bacteria can release toxins (poisons). Streptococcus- toxins cause rash called scarlet fever.



27 IV. Prevention and Treatment A.Prevent bacterial diseases with vaccines, made from another form of the bacteria, stimulates immune system. B. Bacterial infections are treated with antibiotics, substances that stop bacterial reproduction. C. Controlling bacteria- sterilization destroys bacteria by using great heat or chemicals.


29 Ribosome Section 19-1 The Structure of a Eubacterium Go to Section: Cell wall Cell Membrane Pilli DNA Flagellum Peptidoglycan

30 I. What is a virus? A. Virus comes from the Latin word for poison. B. Viruses can only be seen with Electron Microscope C. Non-cellular particle made up of genetic material (DNA or RNA) and a protein coat. Not considered to be living things! D. Parasites! CANNOT carry out life processes unless within a host (living cell). Usually host specific- infect only one type of host.

31 T4 Bacteriophage Tobacco Mosaic Virus Influenza Virus Capsid Tail DNA Tail fiber RNA Capsid Surface proteins Envelope RNA Capsid Section 19-3 Figure 19-13 Virus Structures Go to Section:

32 II. Viral Diseases A. Mostly caused by virus destroying cells in body. B. Cause human diseases such as polio, measles, AIDS, and the common cold C. CANNOT be treated with antibiotics D. Best Protection is prevention - Prevented by safe practices or Vaccine if available. (Vaccines must be used before infection begins)



35 Rabies

36 SARS- flu-like virus that leads to severe pneumonia

37 Ebola virus- liquification of internal organs and severe bleed out

38 E. Oncogenic Viruses cause cancer b/c their DNA disrupts the normal growth of cells F. Retorviruses- RNA – genetic information copied backward- from RNA to DNA example: AIDS


40 III. Kinds of Viruses A. Viruses are classified by their shape, the kind of hereditary material they contain, organism that they infect and reproduction. B. The protein that covers a virus gives it its shape. C. Viruses are often named for the disease that they cause (Polio) or the organ or tissue that they infect (SARS).

41 IV. Viruses are generally destructive. A. Why? Virus has to be inside a living cell to reproduce. The cell that it reproduces in is a host cell. A virus destroys its host cell. How? 1. Lytic Cycle -how a virus reproduces a. When a virus enters a cell and is active it causes the cell to make new viruses. This will eventually destroy the host cell.

42 V. Steps of Lytic Cycle 1. Attach-virus attaches to the surface of a cell 2. Inject- the hereditary material of the virus injects itself into the cell. 3. Copy-the viral DNA takes control of the cell and the cell begins to make new virus particles. 4. Assembles- viral particle are assembled into new viruses 5. Release-the cell bursts open and hundreds of new virus particles are released. These new virus particles go on to infect other cells.

43 Bacteriophage Bacteriophage DNA Bacteriophage protein Bacteriophage protein coat Bacteriophage DNA Bacterial chromosome Lytic Cycle Section 19-3 Figure 19-14 The Lytic Cycle Go to Section: Attach Inject Copy Release Assemble


45 VI. Lysogenic Cycle- When viral DNA becomes part of the cell’s DNA without immediately destroying the cell or making new viruses. A. This is a latent virus; can exist inside host cells for many years. Can become active at any time. Ex- Cold sores.

46 VII. Steps of Lysogenic cycle 1. Virus attaches to the cell and injects hereditary material into the cell. 2. Virus becomes part of the cell’s DNA. 3. Cell divides, creating viral DNA along with its own DNA. 4. This can happen for years until virus becomes active 5. Then it will enter the lytic cycle

47 Bacteriophage DNA Bacterial chromosome Prophage Lytic Cycle Lysogenic Cycle Section 19-3 Figure 19-15 A Lysogenic Infection Go to Section: a) Virus attaches and invades b) Virus’ DNA becomes Part of Cell’s DNA c) Cell divides c) Viral DNA separates from Cell’s DNA and becomes active d) New viruses are made e) Cell breaks open and Releases virus


49 Bovine Spongiform Encephalopathy Mad Cow Disease

50 VIII. Prions- no genetic material (DNA nor RNA) only protein which infects the nervous tissue of the brain (scientists think they cause Mad Cow Disease).

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