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: Single- celled 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 –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