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MCB3020 EXAM 1 ASHGARI 2021 QUESTIONS AND ANSWERS
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MCB3020 EXAM 1 ASHGARI 2021 QUESTIONS AND ANSWERS
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Name: Score:83 Multiple choice questions
Term 1 of 83
49. Define Oligotrophic Environments. How do microbes respond to them?
- Carbon (all polymers)
- Hydrogen (all polymers)
- Sulfur (proteins)
- Phosphorous (nucleic acids)
- Nitrogen (proteins and nucleic acids)
- Oxygen (most)
The ones present: carbons, hydrogens, nitrogen, phosphorus and sulfur
Environments in which nutrients are low. Starvation types of environments.
Oligotrophs typically possess very compact genomes, encoding only a few thousand
genes with small intergenic regions.
Turbidity: degree to which a liquid culture is cloudy
Absorption: related to optical density (how much light is absorbed)
Optical Density: measure of the degree to which bacteria in a solution retard the
transmission of light by absorbing it
Binary Fission: A form of asexual reproduction in bacteria
- N2 gas into NH4 organic nitrogen
- Involved in Nitrogen, Carbon, Oxygen, and Sulfur Cycle
-Archaea can live in extreme conditions such as temperature, salinity and pH
,Term 2 of 83
59. Extremophiles such as microbes found in hot springs in Yellowstone National Park are most
likely members of ___________ domain
Bacterial
Plantae
Fungal
Archaean
Term 3 of 83
Robert Koch:
invented the first microscope to study diseases
connected disease to microbes: one microbe = one disease
introduced the concept of vaccination
developed the first antibiotic
,Term 4 of 83
12. Explain the role of water in biological activities. Define water activity aw, osmosis,
osmolarity, and osmotolerant. What is the significance of Hydrogen bonds in water activities, in
structure and function of proteins and nucleic acids Define halophiles? What strategy do they
use to survive in the presence of high salt concentration?
Halophiles love water / Hydrophobic stabilizes the molecule to conform don't mix with
water
Wherever you find liquid water that is where life can perform because water facilitates
the reaction of molecules
Water is polar and capable of making hydrogen bonds making it an excellent solvent
Holds and absorbs energy making water a temperature buffer
Water has a high Boiling Point because of the hydrogen bonds
1. Water activity: measure of water available in a habitat
2. Osmosis: movement of water in a semipermeable membrane (low to high solute
concentration but high to low water concentration)
3. Osmolarity: concentration of solute particles in a solution
4. Osmotolerant: organisms that are able to grow in wide range of solute/water
concentrations
Chemostat works by maintaining a stable environment by continuously removing old
medium and adding fresh medium.
Benefits of growing culture in a chemostat:
1) Allows organisms to be grown under constant environmental conditions with a steady
state of growth.
2) Allows for close monitoring and control on growth.
A biofilm is a complex of slime enclosed colonies that stick to each other on a surface.
They do this by extracellular polymers collectively called the glycocalyx. They can
engage in quarum sensing and produce harmful chemicals they would not otherwise
produce.
Biofilm can form on both living and nonliving surfaces. However, they are more difficult
to remove when they form in the human body.
Biofilm protects the bacteria from the effects of UV light, immune cells, desiccation
(drying out) and antibiotics. You cannot kill all of the bacteria in a biofilm with antibiotics
because the antibiotic cannot reach the inside of the biofilm. You must physically
remove them to get rid of the bacteria.
, Obligate aerobe- absolutely require O2 for growth because it uses it as its terminal
electron acceptor
Facultative anaerobe- doesn't require O2 but it grows faster with oxygen (so it grows
faster with oxygen as its terminal electron acceptor.
Obligate anaerobe-(strict anaerobe) cannot survive in the presence of oxygen
Aerotolerant anaerobe- grows equally well with or without oxygen
Microaerophile- requires a small amount of oxygen and can not survive in atmospheric
oxygen levels (which are relatively high
In general, an organism can use oxygen based on whether it has catalase and
superoxide dismutase, which are enzymes that break down the toxic byproducts of
oxygen metabolism peroxide and superoxides
1) catalase - neutralizes peroxide
2) superoxide dismutase - neutralizes superoxide
strict anaerobes do not have either (cannot neutralize free radicals)
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