1. Bacteria & Viruses Chapter 21

2. Bacteria vs. Viruses Bacteria Viruses
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 Phylum Shape Motility Metabolism Gram reacion
Cyanobacteria
Bacilli, Cocci
Gliding, some non-motile
Aerobic, photosynthetic autotrophic
Gram-negative
Spirochetes
Spirals
Corkscrew
Aerobic, and anaerobic; heterotrophic
Gram-Pos
Bacilli, cocci
Flagella; some non-motile
Aer/anaer.; heterotrophic, photosynthetic
Mostly gram-positive
Proteobacteria
Bacilli, cocci, spiral
Aer/anaer.; heterotrophic, photosynthetic autotrophic

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
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 Size and shape
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