What is the germ theory of infectious diseases
A specific microbe causes a specific disease in a specific host
What were Robert Koch’s postulates?
- The causitive microbe must ONLY be found in the animal suffering from the disease, not healthy individuals
- The organism should be isolated and cultured in pure culture away from the diseased animals body
- When the organism is inoculated in a healthy individual of the same species, must cause the same effect
- The microbe must be re-isolated again, and when identified should be the same original microbe causing the disease from the original host
Which disease in the past 35 years have been recognized using Kochs postulates?
- covid
- MERS
- SARS
- Viral hemorrhagic fevers (Marburg VHF, ebola VHF, etc)
Explain what Clostridium difficile infection (CDI) is and how to treat it
It is an infection where bad microbes survive the acidity of the stomach and germinate the intestines where the bacteria release toxins causing diahrrhea.
Main issue: messes with antibiotic theory, can cause the antibiotics to destroy good gut bacteria
solution: Feceal microbial transplantation or stool in a pill
What are “invisible killers” and what are 3 examples mentioned in the slides?
New viruses or anti-biotic resistant bacteria
- Tubercolosis
- Flesh eating disease
- VRE
What does the endosymbiont hypothesis address
Where did the first cells come from
What is our current hypothesis?
All cells descencded from the universal ancestor
What are stromatolites
Sedementary rocks made by cyanobacteria from around 3.7-3.8 billion years ago
What were the first cell types to evolve
Prokaryotes, specifically LUCA 4bya
What happened during the first billion years on earth?
Asexual organisms self replicating were thought to evolve by prebiotic processes like chemical stuff etc
Explain the evolution of the universal ancestor and what it is
DNA based cell that all other cell types came from which evolved from RNA
Explain prebiotic syntheses and where the material went
Chemical processes randomly producing material similar to cell componenets like amino acids.
No cells to use them, also anoxic condition, so the materials stuck to objects like clay which catalyzed reactions
What was the hypothesis of how RNA arose
Interactions of abiogenic materials under hot sulfur rich microenvironments gave rise to RNA
What are progenotes and an example?
Early cell like systems.
Ex: self duplicating RNA enclosed by lipophosphate membranes
List the timeline of events in the first billion years
- RNA based cell-like systems evolved
- DNA based cell types (UNIVERSAL ANCESTOR)
- Split of anaerobic prokaryotes into archaebacteria and eubacteria
- First fossil evidence of anaerobic photosynthetic bacteria
- Aerobic photosynthetic autotroph evolution
- aerobic heterotrophs (cyanobacteria)
Describe the characteristics of the universal ancestor and what they are similar to
- prokaryotic cells
- heterotrophic
- anaerobic
similar to eubacteria
What type of eubacteria was thought to evolve from the cenancestor
Non photosynthetic, autotrophic, anaerobic
What are the two possible theories of evolution of archaebacteria
- Non photosynthetic heterotrophic anaerobic eubacteria
- Or the cenancestor
Where did cyanobacteria evolve from and what are they more similar to in terms of function
- photosynthetic eubacteria, but more similar to plants
What is an acid fast stain
Cells in red, acid fast positive
Cells in blue are acid fast negative
Explain gram stains
Gram positive = thick peptidoglycan layer (cocci)
- binds to the cell wall and keeps the stain even when washed with alcohol
Gram negative = thing peptidoglycan (coccobacilus E. coli)
- binds but gets washed off with alcohol
What are abundant in bacterial cells
Ribosomes - 25%
bacterial chromosome and plasmid DNA
Inclusion bodies
What are common features of modern day prokaryotes
Central dogma (RTT) in the same cellular compartment
Genome mostly haploid
no introns
one minor DNA dependant RNA polymerase (primase)
What do eubacteria and cyanobacteria have but not archaebacteria
one major DNA dependant RNA polymerase
