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Prokaryotes

Prokaryotes. Single cell No true nucleus few organelles Archaebacteria – extreme environments Eubacteria. Bacteria and Viruses. Chapter 18. 18.1 Bacteria. Diversity of Prokaryotes. Bacteria are microscopic organisms that are prokaryotes.

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Prokaryotes

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  1. Prokaryotes • Single cell • No true nucleus • few organelles • Archaebacteria – extreme environments • Eubacteria

  2. Bacteria and Viruses Chapter 18 18.1 Bacteria Diversity of Prokaryotes • Bacteria are microscopic organisms that are prokaryotes. • Prokaryotes are divided into two domains—the Domain Bacteria (eubacteria) and the Domain Archaea (archaebacteria).

  3. Bacteria and Viruses Chapter 18 18.1 Bacteria Photosynthetic eubacteria Archaebacteria Eubacteria 3000x 9560x magnification unavailable

  4. Bacteria and Viruses Chapter 18 18.1 Bacteria Eubacteria • Very strong cell walls • Contain peptidoglycan • Some have a second cell wall

  5. Eubacteria • Wide variety of bacteria with different lifestyles • Cell wall for protection from injury – also determines the shape of bacteria • E. Coli – lives in mammal intestines

  6. Bacteria and Viruses Chapter 18 18.1 Bacteria Archaebacteria- aka Extremophiles • Thermoacidophiles (thur muh uh SIH duh filz) live in hot, acidic environments. • Halophiles (HA luh filz) live in very salty environments. • Methanogens (meh THAHN oh jenz) cannot live in the presence of oxygen.

  7. Archaebacteria • Cell walls made from different materials than eubacteria • Cell membrane lipids different from eubacteria • DNA sequences are more like eukaryotes than eubacteria • Live in extreme environments like: great salt lake, hot springs, oxygen deprived mud

  8. Bacteria and Viruses Chapter 18 18.1 Bacteria Differences Between Eubacteria and Archaebacteria • The cell walls of the eubacteria contain peptidoglycan, but the cell walls of archaebacteria do not. • The two groups of organisms have different lipids in their plasma membranes. • Different ribosomal proteins and RNA

  9. Ribosome Cell wall Cell membrane Peptidoglycan Pili Flagellum DNA Bacteria and Viruses Go to Section:

  10. Bacteria and Viruses Chapter 18 18.1 Bacteria Prokaryote Structure • Prokaryotes are microscopic, unicellular organisms. • They have some characteristics of all cells, such as DNA and ribosomes. • Lack a nuclear membrane and other membrane-bound organelles

  11. Bacteria and Viruses Chapter 18 18.1 Bacteria • Chromosomes (no nucleus) • May contain extra DNA in circular plasmid

  12. Bacteria and Viruses Chapter 18 18.1 Bacteria • Capsule- protection, attachment & prevents dehydration • Pili- hair-like projections allowing for attachment & reproduction • Size- very small!

  13. Bacteria and Viruses Chapter 18 18.1 Bacteria Identifying Prokaryotes • Shape • Spherical = Cocci • Rod-shaped = Bacilli • Spiral-shaped = Spirochetes Spirochetes Bacilli Cocci 5460x 2000x 400x

  14. Named by Arrangement: • strep = long chains • staph = clumps, • diplo = pairs • Spirillum/spirochete= corkscrew • Comma-shaped= vibrio

  15. Bacteria and Viruses Chapter 18 18.1 Bacteria Cell Walls • Eubacterial cells have peptidoglycan. • Dyes added to the bacteria identify those with and those without an outer layer of lipid. Purple = gram positivecell wall contains peptidoglycan

  16. Bacteria and Viruses Chapter 18 18.1 Bacteria Movement • Prokaryotic flagella are made of filaments. • Flagella help prokaryotes to move toward materials that they need to survive.

  17. Bacteria and Viruses Chapter 18 18.1 Bacteria Reproduction of Prokaryotes • Binary Fission • Division of a cell into two genetically identical cells • Conjugation • Two prokaryotes attach to each other and exchange genetic information.

  18. Bacteria and Viruses Chapter 18 18.1 Bacteria Survival of Bacteria • Endospores • Resistant to harsh environments and might be able to survive extreme heat, extreme cold, dehydration, and large amounts of ultraviolet radiation

  19. Bacteria and Viruses Chapter 18 18.1 Bacteria Mutations • Bacteria reproduce quickly and their population grows rapidly. • Mutations lead to new forms of genes, new gene combinations, new characteristics, and genetic diversity.

  20. Bacteria and Viruses Chapter 18 18.1 Bacteria Modes of Obtaining Nutrients: Photoautotrophs • Carry out photosynthesis in a similar manner as plants Chemoautotrophs • Break down and release inorganic compounds that contain nitrogen or sulfur Aerobes and Anaerobes • Obligate aerobes are bacteria that require oxygen to grow. • Anaerobic bacteria do not use oxygen for growth or metabolism.

  21. Releasing energy • Obligate aerobes – carry out cellular respiration with oxygen • Obligate anaerobes – cannot live in presence of oxygen • Clostridium botulinum - botulism • Facultative anaerobes – can live with or without oxygen

  22. Bacteria and Viruses Chapter 18 18.1 Bacteria Ecology of Bacteria • Nutrient cycling and nitrogen fixation • Bacteria are decomposers, returning vital nutrients to the environment. • Nitrogen-fixing bacteria live in a symbiotic relationship in the root nodules of plants such as soybeans, clover, and alfalfa.

  23. Bacteria and Viruses Chapter 18 18.1 Bacteria Normal Flora • Most of the bacteria that live in or on you are harmless and are called normal flora. 21,674x E. coli

  24. Bacteria and Viruses Chapter 18 18.1 Bacteria Disease-causing Bacteria • A small percentage of bacteria cause disease. • Bacteria multiply quickly at the site of infection. • Bacteria secrete a toxin.

  25. Bacteria and disease • Pathogens – disease causing agents (small percentage of bacteria) • Treated with antibiotics – block the growth and reproduction of bacteria • Cause disease in two ways: • Break down tissue for food • Tuberculosis • Release toxins that harm the body • Food poisoning • Strep throat – scarlet fever = streptococcus Lung infection

  26. Controlling bacteria • Sterilization – destroy bacteria by subjecting them to great heat or chemical action • Disinfectants – chemical solution that kills bacteria • Refrigeration – bacteria grows more slowly in cold temps. – food • Boiling at high temps to kill bacteria • Salt, vinegar, sugar

  27. Bacteria’s Importance • Photosynthetic producers release oxygen into air • Decomposers: allow recycling of nutrients • Oil spill clean up, sewage treatment

  28. Bacteria and Viruses Chapter 18 18.1 Bacteria Foods and Medicines • Some foods are made with the aid of bacteria. • cheese • yogurt • buttermilk • pickles • vitamins

  29. Nitrogen fixers • Plants depend on nitrogen to make amino acids and proteins →animals get nitrogen from plant proteins • Nitrogen from atmosphere must be converted to ammonia NH3 before plants can use it • This is done by “nitrogen-fixing” bacteria • Symbiotic relationship between plants and bacteria - Rhizobium

  30. Bacteria and Viruses Chapter 18 18.2 Viruses and Prions Viruses • A nonliving strand of genetic material within a protein coat • No organelles to take in nutrients or use energy • Cannot make proteins • Cannot move • Cannot replicate on their own

  31. Structure • Contain a nucleic acid and protein • HEAD region • Capsid--protein coat with nucleic acid core • TAIL region • to attach to bacteria/cells

  32. Bacteria and Viruses Chapter 18 18.2 Viruses and Prions Viral Infection • In order to replicate, a virus must enter a host cell. • The virus attaches to the host cell using specific receptors on the plasma membrane. • Many viruses cannot be transmitted between different species.

  33. Viral recognition and attachment • Virus must recognize specific receptor site on host cell • Part of virus matches site on host, lands and locks in • Attachment is specific- virus can only enter and reproduce in a few types of cells • I. E. - tobacco mosaic virus cannot infect human cells even though we are exposed to it daily

  34. RNA DNA Head RNA Capsid Capsid proteins Tail sheath Tail fiber Surface proteins Membrane envelope Figure 19-9 Virus Structures Section 19-2 Tobacco Mosaic Virus T4 Bacteriophage Influenza Virus

  35. Reproduction • Must take place inside a host cell • Infection--chance contact • Lytic Infection – • Viral DNA takes over host nucleus, produces new viruses • Lysis of host cell – bursts and dies – new viruses are released

  36. Bacteria and Viruses Chapter 18 18.2 Viruses and Prions Lytic Cycle • The host cell makes many copies of the viral RNA or DNA. Lysogenic Cycle • Viral DNA inserts, or integrates into a chromosome in a host cell. • Infected cell will have the viral genes permanently.

  37. Figure 19-10 Lytic and Lysogenic Infections

  38. Bacteria and Viruses Chapter 18 18.2 Viruses and Prions

  39. Bacteria and Viruses Chapter 18 18.2 Viruses and Prions Retroviruses • Viruses that have RNA instead of DNA for their genetic material • Retroviruses have a protein capsid. • Lipid envelope is obtained from the plasma membrane of a host cell

  40. Figure 19-11 Viruses and Cells Section 19-2

  41. Pathogenic viruses • Ebola zaire-- • AIDS • rhinoviruses • influenza • measles, mumps, chicken pox • polio • rabies • smallpox

  42. Vaccines • “cow pox”--Edward Jenner • 1796 • Human Papilloma Virus (HPV)- GARDASIL by Merck • 2008

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