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MGY277 Exam Latest Update
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MGY277 Exam Latest UpdateWho is Akshamsaddin and how did he arrive at his conclusion - Answer A 1400s Turkish
scientist who claimed that dis eases like plants and animals have "invisible seeds"
Who is van Leeuwenhoek and how did he arrive at his conclusion? - Answer (Dutch
17-18 c) The first person to see microbes with a microscope. Used microscopes for
linen - created his own for microbes.
Who is Semmelweis and how did he arrive at his conclusion? - Answer (Vienna 19c)
Obstetrician, found that two different hospitals had different mortality rates - found that
doctors performed autopsies and then delivered patients without hygiene.
Who is Bassi and how did he arrive at his conclusion? - Answer (18-19c) Found a group
of fungal pathogens that kill different species of insects
Who is Koch and how did he arrive at his conclusion? - Answer (German 19-20c)
Physician/founder of modern bacteriology. Discovered the causes of anthrax, cholera,
tuberculosis, developed techniques for working with microbes in labs
Who is Pasteur and how did he arrive at his conclusion? - Answer (French 19c)
Microbiologist, didn't believe in spontaneous generation, biggest contributor to germ
theory developed techniques for vaccine production. Showed that microbes don't grow
in liquid until introduced
Who is Lister and how did he arrive at his conclusion? - Answer (19-20c) Worked on
fermentation, wondered if minute organisms were responsible for pus in wounds, found
that cuts introduced infection. Developed surgical sterilization by adding carbolic acid
to wounds, encourages sterilization on instruments and clean operating rooms
What else did Pasteur do? - Answer Develop rabies and anthrax vaccine, pasteurization.
Discovered staph aureus, pyogenes, pneumococcus, anaerobic fermentation by
microbes, new pathogens of silk worms
Why use carbolic acid? (Lister) - Answer Carbolic acid contains phenol - a germicidal
compound that kills bacteria and is non-toxic
What were Koch's postulates? - Answer 1. same pathogen in all cases of a disease
2. pathogen needs to be isolated and grown separately in pure culture
3. new pathogen from pure culture must cause same disease again when introduced to
healthy
4. pathogen from healthy host must be same as original pathogen
Microbes meeting all requirements are the cause of disease
,How did the germ theory discoveries build on each other? - Answer Akshamsaddin
(invisible seeds) -> Semmelweis + Lister (nonhygienic practice = disease) -> Pasteur
(disprove spontaneous generation) -> Koch (cause of disease)
What impact has infectious disease (and the control of infectious disease) had on the
human population? - Answer Before: mass infection, mass death, regular outbreaks
After: increase life expectancy, fewer outbreaks, no longer leading cause of death,
vaccines, antibiotics, public health infrastructure
What are the major categories of microbes? - Answer The living: prokaryotes: bacteria,
archaea. Eucarya.
The non-living: viruses, viroids, prions
How can microbes be useful? - Answer Agriculture: Plants + animals need nitrogen,
bacteria provide nitrogen fixing convert N2 to ammonia
Oxygen: bacteria invented photosynthesis, generated oxygen.
Food production: (yogurt, cheese, beer)
Biotechnology: (E. coli used to clone DNA, insulin produced using bacteria or yeast)
MSG
What are the key differences between Bacteria and Archaea? What about similarities? -
Answer Differences: Peptidoglycan wall (only bacteria), ribosome and transcription
(archaea more similar to eucarya),
Lipid membrane,
rRNA sequence divergence (maybe how archaea and bacteria separated).
Similarities: size, shape, appearance
What are the defining features of fungi, protozoa and helminths? - Answer Fungi:
single-cell, multicellular, micro/macroscopic, degrade organic material, land food
source.
Protozoa: single-cell (<prokaryotes), microscopic, motile, non rigid cell wall, ingest
organic material, land water.
Helminths: multicellular
Why are some non-microbes part of the study of microbiology? - Answer Some infect all
life forms, still cause disease
What is the evidence for the two domain system? - Answer Phylogenetic models that fit
data better, greater sampling of prokaryotes, more gene families used in analysis = 2
domain eukaryotes branch from archaea instead of 3 domains
, What is the definition of magnification? - Answer The increase in apparent size of an
object compared to the size of the actual object
What is the definition of refraction? - Answer When light rays change direction due to a
change in medium through which they travel
Refraction index: measure of relative speed of light as it passes through medium
What is the definition of resolution? - Answer The ability to see objects (or points) as
distinct instead of a blur that combines them - aka the minimum distance at which two
points can be distinguished as individuals
What is the definition of contrast? - Answer The ability to see objects against the
background
What are the lenses of a bright field microscope? - Answer *
How do you calculate total magnification in a light microscope given the power of the
different lenses? - Answer *
Why and when oil is used in a light microscope? - Answer Oil is used to displace air
between lens and specimen, prevents light from missing objective lens. Use oil on 100x
bright-field
What is the difference between bright and dark field light microscope - Answer Cells
stand out as bright against a dark background in dark field, opposite in light field
What are the fundamental differences between electron and light microscopy and the
advantages and disadvantages of each? - Answer Differences: electromagnetic lenses,
electrons, fluorescent screen replaces glass lenses, visible light and eye. Higher
resolving power (1000>0.3)
ELM dis: lenses and specimen must be in vacuum - specimen dead, but high detail
BF dis: can't see viruses, not high detail, but specimen alive
What are the different images obtained from scanning and transmission EM? - Answer
TEM - fine details of cell structure
SEM - objects appear 3D, surface details
What are the steps of a Gram-stain and the basic reason why some cells stain purple
while others do not? - Answer 1) crystal violet (primary stain: stains cells purple), 2)
iodine (mordant: cells remain purple), 3) alcohol (decolorizer: gram + cells remain
purple, gram - cells become colorless), 4) safranin (counterstain: gram + remain purple,
gram - appear pink)
Peptidoglycan in cell wall causes purple stain
What is the acid-fast stain is used for? - Answer To detect small group of organisms that
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