Misc.
What is the "magic bullet"?
Antibiotics are harmful to specific bacteria without harming eukaryotic organisms.
The evolutionary history and relatedness of organisms is
phenology
Describe the difference between the lytic and lysogeny cycle
Lysis ends in the rupture of the host cell while the lysogeny cycle integrates the phage genome into the host cell=prophage! And doesn’t kill the host immediately.
Explain the difference between sterilization and commercial sterilization
Sterilization destroys all living cells, spores, and viruses, while commercial kills all spores in foods (not actually considered sterilization) , C. botulinum.
Entamoeba hystolytica
causes intestinal amebiasis
What is the difference between host range and tissue tropism (broad and narrow)?
Both heavily rely on surface receptor molecules. Host range: infects a particular group of host species. Tissue Tropism: the range of tissue types a virus can infect.
Dimorphic fungi are yeast-like at what temperature and mold-like at what temperature?
Yeast-like: 37 degrees
Mold-like: 25 degrees
Define eclipse period and rise period
the phase of viral replication where no infectious virions are detectable inside the host cell (eclipse period), followed by the phase where newly assembled virions are released and detected outside the cell (rise period).
Define thermal death point, thermal death time, and decimal reduction time.
TDP: lowest temperature at which all cells in a liquid culture are killed in 10 minutes, TDT: minimal time for all bacteria to be killed at a certain temp, DRT: time it takes to reduce a microbial population by 90%.
Naegleria flowleri
Causes primary amebic meningoencephalitis
Given the mechanism by which viruses infect cells, how might an organism evolve to become resistant to a viral infection?
Surface binding receptor changes so the virus does not recognize it anymore.
Name the 4 types of protozoa and their type of movement
amoebas: move with pseudopod, ciliates: move with numerous cilia, flagellates: move with one or long flagella, apicomplexans: non-motile
Explain the HPV replication cycle
1. Virion binds to cell-surface receptors and becomes endocytosed by the host cell.
2. Virion docks onto the nuclear membrane.
3. Genome is uncoated.
4. Viral DNA uses host polymerases for transcription.
5. Translation takes place in the cytoplasm.
6. Translated capsid proteins return to the nucleus for assembly into progeny virions.
7. Shedding of epithelial cells releases virions.
What types of microbes are killed by high, intermediate, and low levels of disinfection?
High: all (vegetative, mycobacteria, spores, fungi, viruses), Int: all but spores, low: some viruses, fungi, and vegetative.
Acanthamoeba
Causes corneal infection (keratitis)
High risk for contact wearers
Explain how to read a plaque assay test
If you see clear plaques, it indicates a lytic phage is present; if you see no visible difference in the bacterial lawn, a lysogenic phage is present.
What is mycelium, and what is the advantage of it?
It is a network of fungal branches. It increases the surface area, which helps increase absorption.
Explain the influenza replication cycle
1. A flu A virion attaches to a cell by its HA envelope protein binding a receptor protein.
2. Virion uptake and lysosome fusion.
3. (-) RNA and RNA-dependent RNA polymerase are released and enter the nucleus.
4. Transcription primed by capped host mRNA.
5. (-) mRNA translation
6. (+) mRNA translation: envelope proteins enter ER and Golgi for transfer to the cell membrane.
7. NP packaging proteins return to the nucleus.
8. From (+) RNA, make (-) RNA genomes to package in virions.
9. Viral RNA genome segments bind NP packaging proteins and exit the nucleus.
10. Virion assembles, including matrix and envelope.
11. NA cleaves host receptor, releasing virion to bud out.
What are the three factors on which the efficacy of disinfectants relies?
Presence of organic matter, variety of microbes present, and concentration of agent.
Toxoplasma gondii
Needs apical complex to enter RBCs
apicomplexan
asexual reproduction occurs in humans
sexual reproduction occurs in cats
What is used for gas sterlization?
gamma irradiation or antimicrobial gases --> ethylene oxide
Explain ciliate conjugation
Starts with a micronucleus (2n) and a macronucleus, ¾ of meiotic products disintegrate, leaving one micronucleus (n). Haploid micronuclei exchange and fuse to become a diploid (2n). Macronucleus reforms.
Explain the HIV replication cycle
1. HIV virion attaches
2. Virion fuses to the membrane and releases its core into the cytoplasm.
3. The core dissolves, and the RNA chromosomes are copied to make ds DNA.
4. The ds DNA enters the nucleus through a nuclear pore.
5. The viral DNA integrates in a host chromosome.
6. Full length RNA transcripts are made.
7. Viral RNA transcripts express capsid and reverse transcriptase proteins.
8. RNA transcripts exit the nucleus to form RNA dimers for progeny virions.
9. Env proteins are made and enter ER, then Golgi.
10. Env. proteins are exported to the cell membrane.
11. The membrane-embedded evc proteins assist the packaging of the RNA dimers plus MA and CA peptides into the core.
12. Core particles assemble and are coated with envelope, and then released from tetherins.
What are the agents used for each level of disinfection?
High: ethylene oxide, glutaraldehyde, and formaldehyde
Int: Phenolics and halogens
Low: Alcohols
Malaria tranmission cycle
1. A mosquito injects sporozoites into a human host
2. Sporozoites travel to the liver and undergo schizogony to produce merozoites
3. Merozoites infect RBCs and develop into trophozoites