Transcript Micro organisms

Micro-organisms
Unit 7
Germ Theory
Proposed by Scientist: Luis Pasteur.
All diseases are caused by small
organisms that can only be seen with
a microscope.
Led to the discovery of pathogens
(germs)
– Bacterial Pathogens
– Viral Pathogens
Kingdom Monera: Bacteria
Basic info
Cell Number: Singlecelled
Cell Type: Prokaryotic
Feeding: Hetero OR
Autotrophic
Reproduction: Mostly
asexual reproduction
Appeared 3.5 billion
years ago
2 Domains
– Archaebacteria
– Eubacteria
Archaebacteria
Primitive bacteria
that live in harsh
conditions.
3 types
– Methanogens
Convert hydrogen
and carbon dioxide
to Methane
– Extreme halophiles
High salt
concentration
– Thermoacidophiles
High acid or high
temperature
Eubacteria
Modern Bacteria
classified by shape
and reaction to
Gram stain
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Bacilli: rod
Spirilla: spiral
Cocci: round
Diplo: paired
Strepto: chains
Staphylo: clusters
– Gram Stain
Positive: purple
Negative: red
BACTERIA
Structure of Bacteria
Cell membrane
Cytoplasm
Single Circular Chromosome
(Sometimes) Endospore
– Protect cell form harsh climate
(Sometimes) Flagella or Cillia
– Movement
Draw and label a simple bacilli
bacteria in your notes…
Pathogenic Bacteria
make you sick!
Antibiotics- medicine for treating
diseases caused by bacteria
– Interfere with cell production
– Do not help against viruses!!!!
Antibiotic Resistance
Caused by using antibiotics too much
or incorrectly
– Bacteria evolve (by natural selection) to
resist the meds
New methods or different antibiotics
must be used.
Antibiotic resistance video…
Good Bacteria help you!
Non-pathogenic bacteria used for…
– Digestion
– Sewage breakdown
– Nitrogen cycle (needed plant nutrients)
– Making food (Yogurt and cheese)
No Kingdom: Viruses
Viruses
Nonliving infectious particle with a
protein coat and a nucleic acid
(either DNA or RNA)
Virology
Study of viruses
Late 1800’s people knew that
“factors” caused disease
All viruses are bad, but we learned to
manipulate them for our advantage
– Tobacco mosaic virus – used for gene
therapy
Viral Reproduction
2 cycles – Lytic and Lysogenic
Lytic Cycle (Ex: Ebola)
Present in virulent (fast) viruses
– 1. Attach to cell
– 2. Insert viral DNA into host cell
– 3. Replicate viral DNA using host cell
– 4. Assemble new viruses
– 5. Destroy host cell to release new
viruses
End product is more viruses and a
dead cell
Lysogenic Cycle (Ex: HIV)
Delayed virus cycle; dormant viruses
– First two steps are the same as lytic
– 3. Insert viral DNA into host DNA
– 4. Viral DNA is replicated when host cell
divides
– 5. Virus enters the lytic cycle at any
time to kill the cell
*Can be manipulated for gene
therapy by replacing viral DNA with a
desired gene
Virus Cycles
Fighting Viruses
Immune system: can fight off most viruses
without meds
Best treatement option: prevent infection
before exposure with a vaccine of dead/weak
viruses; body will build immunity;
– Can lead to eradication if everyone is
vaccinated
– Doesn’t work post-infection
Antiviral drugs (very rare)
– Interfere with virus replication
– Ex: Tamiflu