1 / 25

Bacteria & Viruses Chapter 21

Bacteria & Viruses Chapter 21. Bacteria vs. Viruses. Bacteria Fully functioning cellular organisms Lack a nucleus Reproduce asexually - binary fission Viruses Obligate intracellular parsites Reproduce inside bacteria, plant cells, animal cells capsid. Bacteria vs. Viruses.

betty
Download Presentation

Bacteria & Viruses Chapter 21

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Bacteria & VirusesChapter 21

  2. Bacteria vs. Viruses • Bacteria • Fully functioning cellular organisms • Lack a nucleus • Reproduce asexually - binary fission • Viruses • Obligate intracellular parsites • Reproduce inside bacteria, plant cells, animal cells • capsid

  3. Bacteria vs. Viruses Virus Bacteria

  4. Bacteria – Gram Stains • Gram-positive retain stain and appear purple • Have thicker layer in cell wall. • Gram-negative do not retain stain and take second pink stain instead.

  5. Gram Stains

  6. Bacteria: Key Characteristics • Single-celled • Prokaryotic • Oldest living organisms • Most common type of prokaryote

  7. Bacteria Classification • Nutrition • Reactivity to oxygen • Archaebacteria vs Eubacteria

  8. Bacteria Classification - Nutrition • Autotrophs • Photoautotrophs: photosynthetic autotrophs produce energy from light (blue-green algae) • Chemoautotrophs: produce energy from inorganic substances • Heterotrophs • Bacteria that feed off of hosts

  9. More Bactiera Nutrition - Heterotrophic Prokaryotes • Most free-living bacteria are chemoheterotrophs that take in pre-formed organic nutrients • As aerobic sapotrophs, there is probably no natural organic molecule that cannot be broken downby some prokaryotic species

  10. Bacteria Classification: Reactivity to Oxygen • Obligate Aerobes: requires oxygen for respiration & growth • Obligate Anaerobes: oxygen serves as a poison – must avoid! • Facultative Anaerobes: can use oxygen if available but can also survive without it

  11. Bacteria Classification:Archaebacteria vs Eubacteria • Archaebacteria • Live in extreme environments • Extreme Halophiles: “salt lovers” live in environments w/ high salt concentration • Methanogens: bacteria that produce methane as a waste product • Thermoacidophiles: bacteria that love hot acidic environments

  12. Types of Archaea • Methanogens: live under anaerobic environments where they produce methane (eg marshes) • Halophiles: require high salt concentrations (eg Great Salt Lake) • Thermoacidophiles: live under hot, acidic environments (eg geysers)

  13. Bacteria Classification:Archaebacteria vs Eubacteria • Moderate environments • Categorized according to shape, motility, cell-wall composition, pathogenic nature • Proteobacteria • Gram-positive bacteria • Gram-negative bacteria • Cyanobacteria • Spirochetes • Chlamydias • Chemosynthetic bacteria • Nitrogen-fixing bacteria ****BE ABLE TO DESCRIBE EACH OF THE ABOVE BACTERIA!!***

  14. Structure of Prokaryotes • Outer wall strengthened by peptidoglycon (molecule containing amino disacharride & peptide fragments • Some move by use of flagella • Adhere to surfaces by means of fimbriae

  15. Reproduction in Prokaryotes • Reproduce asexually through binary fission • Mutations are chief means of genetic variation

  16. Kingdom Archaebacteria • First discovered in extreme environments • Methanogens: Harvest energy by converting H2 and CO2 into methane gas • Anaerobic, live in intestinal tracts • Extreme halophiles: Salt loving • live in Great Salt Lake, and Dead sea. • Thermoacidophiles: Live in acid environments and high temps. • Hot Springs, volcanic vents

  17. Kingdom Eubacteria • Spirillum – spiral-shaped • Bacilli – rod-shaped • Cocci – round or spherical

  18. Viruses • Noncellular parasitic agent consisting of an outer capsid and an inner core of nucleic acid • Have DNA or RNA genome, but can only reproduce by using the metabolic machinery of a host cell

  19. Viral Structure • Shape: varies from theadlike to polyhedral • All viruses have same basic anatomy: outer capsid with protein subunits & inner core of nucleic acid

  20. Categorizing Viruses • Type of nucleic acid • DNA or RNA (not both) • Single-stranded or double-stranded • Size and shape • Presence or absence of an outer envelope

  21. Viruses: Parasitic Nature • Obligate intracellular parasites • Host Specific: infect a variety of cells • Viruses can mutate • Viruses evolve & reproduce, but they are not obligate intracellular parasites – they only grow inside their specific host cells

  22. Lytic Cycle & Lysogenic Cycle

  23. Lytic Cycle • 5 Stages 1. Attachment: capsid combines with receptor 2. Penetration: viral DNA enters host 3. Biosynthesis: viral components are synthesized 4. Maturation: assembly of viral components 5. Release: new viruses leave host cell

  24. Lysogenic Cycle • Viral DNA integrated into host DNA • The phage becomes a prophage that’s integrated into the host genome • Bacteriophage (phage): viruses that parasitize bacteria • Phage may reenter lytic cycle; reproduction and release of the virus then occur

  25. Viroids and Prions • Viroids- naked strands of RNA, directs the cell to make more viroids • Prions- (proteinaceous infectious particles), newly discovered disease agents that differ from viruses and bacteria

More Related