• Prokaryotes range from 1-5 μm
• Exception:
– Epulopiscium fisheloni is 500 μm!

• Old system
– One kingdom: Monera
• New system
– 2 kingdoms
• Eubacteria (Domain Bacteria)
• Archaebacteria (Domain Archaea)

• Bacillus (pl bacilli)
– Rod-shaped
• Coccus (pl cocci)
– Spherical
• Spirillum (pl spirilla)
– Spiral-shaped

• Gram staining can be used to differentiate bacteria
– Thick wall of peptidoglycan—purple color
– Thin/no wall—pink/red color

Identify it!

Identify it!

Identify it!

Identify it!

• Nonmotile
• Flagella
Escherichia aurescens
Escherichia coli

• Spiral movement
• Glide on slime
Spirillum volutans
Myxobacterium

• Bacteria can be either heterotrophic or autotrophic
– Heterotrophic —does not produce own food source
– Autotrophic —does produce own food source

• Chemoheterotrophs - take in organic molecules for energy and carbon source
– EX: E. coli
• Photoheterotrophs - photosynthetic, but needs organic molecules for a source of carbon

• Photoautotrophs - use light energy to convert
CO
2 and water into organic compounds and O
– EX: cyanobacteria— “blue green algae”
2
• Chemoautotrophs - make organic molecules from CO of light
2 but use chemical reactions instead
– Live deep in ocean vents

• Obligate aerobes —need O
2 to live
– Ex Mycobacterium tuberculosis
• Obligate anaerobes —die with O
2
– Ex Clostridium botulinum
• Facultative anaerobes —either or
– Ex E. coli

• Binary fission —grow, double cellular components, and divide

• Conjugation– hollow bridge forms so that bacteria can exchange genetic material

• Spore formation – bacteria can form spores when growth conditions become bad (too hot/cold, too dry, no food)
– Protective barrier
– When conditions are good again, bacteria will grow again

• Decomposers-
• Nitrogen Fixers-
• Human uses-

• Iwanowski and Beijernick (1890’s)
– Worked on Tobacco Mosaic Virus (infects tobacco and tomato leaves).
– Creates mosaic pattern on leaves.
– Made a juice of the infected leaves and then put this juice through a filter. Rubbed the filtered juice onto leaves. Still became infected. Concluded that whatever these disease causing particles were, they were very small (smaller than bacteria).
• Named them viruses meaning “poison”.

• Stanley (1935)
– Purified TMV into a crystal.
– Living particles don’t crystallize therefore, viruses are non-living pathogenic (disease causing) particles.

• Particles of nucleic acid , protein and sometimes a lipid envelope .
• Obligate intracellular parasite (can only replicate within a living cell)

• Small – 20nm (polio virus) – 350nm (small pox virus)
• Single type of nucleic acid (RNA or DNA but never both)
• Protein coat – capsid
• Some have envelopes (made of lipids)outside of capsid
• Surface projections made up of lipids for attachment onto host cells
• Are specific to their host

• Shapes are
– Rod
– Helical
– Icosahedral (20 sides)

• Particles of nucleic acid , protein and sometimes a lipid envelope .
• Obligate intracellular parasite (can only replicate within a living cell)

• Infect E. coli bacteria
• Attach with tail fibers onto cell.
• Inject nucleic acid into cell

• Get in, replicate and get out to invade other host cells
• Virulent (Disease causing)
• The cold, rubella (German measles), mumps
Release
Attachment at Receptor site
Entry
Assembly
Replication

Attaches onto host cell Injects DNA into host cell Replication of Viral parts
Reassembly of virons Lysis – bursting out
Viruses that reproduce only by the lytic cycle are called Virulent

• Virus embeds its DNA into hosts DNA which is replicated with host cell’s DNA.
• Remains unnoticed for sometimes years
• AIDS, cold sores, chicken pox, hepatitis
Prophage
Attachment Integration Cell multiplication
& Injection of nucleic acid
Prophage remains unnoticed and not transcribed

• Measles, Mumps, Rubella, Rabies, the Cold, the Flu, Influenza, Hepatitis, AIDS, Chicken pox, Small pox, Polio, Yellow fever,
Meningititis, some cancers
• Vaccines are small doses of either killed, altered or live viruses. Body builds up antibodies against virus

• AIDS
• The Cold
• Measles
• Mumps
• Rubella
• Chicken pox/Shingles
• Small Pox
• Hepatitis
• SARS
• The Flu
• Ebola
• HPV
• Bird Flu
• Polio

• Retroviruses – AIDS. Contains RNA instead of DNA.
Goes from RNA to DNA to RNA to protein. Normal is DNA to RNA to protein.
• Viroids – another disease causing agent but no
capsid, only the RNA.
– Found only in plants
• Prion – viral proteins that cause diseases. Scrapie in sheep degrades nervous system. Mad Cow disease
(Bovine spongiform encephalopathy) in cows – puts holes into brain.
– In humans, its Creutzfeld-Jakob disease & Kuru.

Diseases Caused by Bacteria and Viruses

1. What is a pathogen?
2. Okay, now the bad. Name the two ways
bacteria cause disease in living organisms.
3. How can bacterial diseases be prevented?

4. How can they be treated?
5. Make a list of human diseases caused by bacteria.
6. What does it mean to sterilized a substance?

7. How can we prevent bacteria from spoiling
our food?
8. What do viruses do to us to produce disease?
9. How are viral diseases treated and
prevented?

10.What is non-effective at treating viral diseases?
11.List 9 diseases caused by viruses in humans
12.How are most plant diseases spread?

13. What is a prion?
14. Why are viruses not considered to be
alive?