Topic 5
What is coevolution hypothesis?
viruses originated about the same time as other microbes and have been coevolving with them
What are aerotolerant anaerobes?
aren't harmed by O2 but don't use it
What are the two types of endospores-forming, gram positive bacteria?
- Bacillus
- Clostridium
Typically where are mycobacterium and actinobacterium found?
soil
What is an autoclaves conditions?
- 121 degrees
- 15 psi
What are the exceptions to viruses sizes?
- Megavirus chilensis
- Mimivirus
- Pandoravirus
What is anabolism and catabolism?
Anabolism: nutrients from outside of the cell are transformed into new cell material
Catabolism: energy is often derived from the oxidation of chemical compound
What are heterocysts?
they have a thick wall that slows down the diffusion of O2 into the cell.
What is the lag phase?
microbes are preparing for steady growth
Why is it so rare for a eukaryote to be a thermophile and survive in higher temperatures?
Because mitochondria are mesophiles, so they won't function properly in extreme temperatures.
Compare the lytic cycle to the lysogenic cycle
lytic cycle: viruses enter, replicate and lyse the host cell
lysogenic cycle:
◦Phage integrates it's genome with the host, becoming a prophage
◦This genome is replicated until the host starts to stress (host becomes a lysogen)
◦The phage then lyses the cell
What is pasteurization?
it reduces the number of microorganisms in foods, reduces viable cell abundance so spoilage is reduced
What are the general characteristics of Firmicutes?
- gram-positive
- either has a low GC
What is the minimum, maximum and optimal temperature for psychrophiles?
minimum: 0 degrees
maximum: 20 degrees
optimal: 15 degrees
What are 3 ways for a virus to enter an animal cell? Explain at least 1 of them in detail.
- Endocytosis
- Membrane fusion
- Endocytosis of an enveloped virus
What are the steps viral replication?
1. adhere: stick to a host cell
2. enter the cell
3. uncut: release genome
4. synthesis: express and replicate genome
5. assembly: create a new virus particle
6. exit: new particle leaves cell
Explain the use of phenolic compounds as a disinfectant with an example?
What are the characteristics of methanotrophs?
- able to oxidize methanol and other C1 compounds that don't have carbon-carbon bonds
- has an enzyme called methane monooxygenase which is used to oxidize methane and methanol.
- obligate aerobes
- founds in thermocline between anoxic zones
- they can be symbionts of marine mussels, found in the mussel lung tissue
What do depth filters do?
- it is a fibrous sheet or mat
- has randomly overlapping fibres of different substances
- used as a pre-filter and removes suspended particles on a " trapping action
What are 4 ways to quantify viruses?
- Direct count
- Hemagglutination
- Plaque assay
- Endpoint assay
How do prions replication?
1. A PrPSc prion protein contract a PrPc protein
2. The PrPSc induces a conformational change in a PrPc converting it to a prion
3. A few PrPSc proteins convert many PrPc into prions
4. Prions form fibrils, thought to lead to disease.
What are features that provide thermal stability?
- critical aa substitutions in key location produce heat-tolerant folds
- increases in ionic bonds between acidic and basic residues: resists unfolding in aqueous cytoplasm
- certain solutes help stabilize proteins
- modification in cytoplasmic membrane (saturated fatty acids in Bacteria)
- phospholipid monolayer in Archaea more thermotolerant than bilayers
Coliforms are ....
- _____ shape
- gram-______
- _______ forming
- motile or non-motile
- ferment _____
- produces _____
- _____ bacteria
- found in ______,_______ and _______
- acts as an _______ organism for pathogens
- rod shape
- gram-negative
- non-spore forming
- motile or non-motile
- ferment lactose
- produces acid
- enteric bacteria
- found in water, soil and plant saprophytes
- acts as an indicator organism for pathogens
What is the purpose of temperature manipulation?
- denatures proteins and nucleic acid
- 100 degree kills most microbes quickly
- an autoclave adds pressures which keep liquid from evaporating during high temps
Name one broad-spectrum antibiotic and one narrow-spectrum antibiotic.
Broad: Tetracycline
Narrow: Polymyxin B, penicillin, streptomycin...