Transcript Eubacteria (Domain Bacteria)

Viruses and Bacteria
Bacterial sizes
• Prokaryotes range from 1-5 μm
• Exception:
– Epulopiscium fisheloni is 500 μm!
Classification
• Old system
– One kingdom: Monera
• New system
– 2 kingdoms
• Eubacteria (Domain Bacteria)
• Archaebacteria (Domain Archaea)
Archae is more like us
(Eukarya) because we
share key genes
Bacteria Shapes
• Bacillus (pl bacilli)
– Rod-shaped
• Coccus (pl cocci)
– Spherical
• Spirillum (pl spirilla)
– Spiral-shaped
Cell Wall
• 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!
Movement
• Nonmotile
Escherichia
aurescens
• Flagella
Escherichia
coli
Movement
• Spiral movement
Spirillum
volutans
• Glide on slime
Myxobacterium
Metabolism
• Bacteria can be either heterotrophic or
autotrophic
– Heterotrophic—does not produce own food
source
– Autotrophic—does produce own food source
Heterotroph types
• Chemoheterotrophs- take in organic
molecules for energy and carbon source
– EX: E. coli
• Photoheterotrophs- photosynthetic, but
needs organic molecules for a source of
carbon
Autotroph types
• Photoautotrophs- use light energy to convert
CO2 and water into organic compounds and O2
– EX: cyanobacteria— “blue green algae”
• Chemoautotrophs- make organic molecules
from CO2 but use chemical reactions instead
of light
– Live deep in ocean vents
Releasing energy
• Obligate aerobes—need O2 to live
– Ex Mycobacterium tuberculosis
• Obligate anaerobes—die with O2
– Ex Clostridium botulinum
• Facultative anaerobes—either or
– Ex E. coli
Growth and Reproduction
• Binary fission—grow, double cellular
components, and divide
Growth and Reproduction
• Conjugation– hollow bridge forms so that
bacteria can exchange genetic material
Growth and Reproduction
• 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
Importance of bacteria
• Decomposers-
• Nitrogen Fixers-
• Human uses-
History of Viruses
• 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”.
History of Viruses
• Stanley (1935)
– Purified TMV into a crystal.
– Living particles don’t crystallize therefore, viruses
are non-living pathogenic (disease causing)
particles.
Viruses
• Particles of nucleic acid, protein and
sometimes a lipid envelope.
• Obligate intracellular parasite (can only
replicate within a living cell)
Structure of a Virus
• 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
Structure of a Virus
Viral Shapes
• Shapes are
– Rod
– Helical
– Icosahedral (20 sides)
Viruses
• Particles of nucleic acid, protein and
sometimes a lipid envelope.
• Obligate intracellular parasite (can only
replicate within a living cell)
Bacteriophage
• Infect E. coli bacteria
• Attach with tail
fibers onto cell.
• Inject nucleic acid
into cell
The Lytic Cycle
• 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
The Lytic Cycle of Virus infection
Attaches onto host cell
Injects DNA into host cell
Reassembly of virons
Replication of Viral parts
Lysis – bursting out
Viruses that reproduce only by the lytic cycle are called Virulent
Lysogenic Infection
• 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
& Injection
Integration
of nucleic acid
Cell multiplication
Prophage remains unnoticed and not transcribed
Viral Diseases
• 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
Diseases Caused by Viruses
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AIDS
The Cold
Measles
Mumps
Rubella
Chicken pox/Shingles
Small Pox
Hepatitis
SARS
The Flu
Ebola
HPV
Bird Flu
Polio
The Different Forms of Viruses
• 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?