MT1 > Ecology of Bacteria and Viruses Flashcards
What 2 main factors differentiate Bacteria/Archaea from Viruses?
Bacteria/Archaea:
- Are unicellular living organisms with no organelles
- Have a complete set of RNA (rRna, tRNA)
What environments can support bacterial growth?
Almost every environment on earth, even extreme ones.
What are the 6 main characteristics of bacteria (+Archaea)?
- Self-feeding
- Self-replicating (growth)
- Differentiation (sporulation)
- Chemical signalling (quorum sensing)
- Movement
- Evolution
Describe the characteristics of an autotrophic organism.
Derives energy from light or chemical oxidation. Derives carbon from CO2 or carbonate.
Describe the characteristics of a heterotrophic organism.
Derives energy from oxidation of organic molecules. Derives carbon from metabolic intermediates.
What does Liebig’s Law of the Minimum stipulate?
Growth is not controlled by the total amount of resources available, but by the scarcest resource (limiting factor).
What is a real world example of Liebig’s Law of the Minimum at work?
Plant growth often is not limited by water or sunlight, but rather by nitrogen or phosphate in the soil.
How can iron act as a limiting factor (as in Liebig’s Law of the Minimum)?
Iron is critical for several metalloproteins in the body, and several bacteria have evolved iron carriers to take advantage of ferric iron in the body.
What 2 principles constrain Liebig’s Law of the Minimum?
- Only applicable under steady-state conditions (non-transitioning ecosystem)
- Limiting factor may change according to interaction of environmental variables
What does Shelford’s Law of Tolerance stipulate?
Success of an organism relies not only on the availability of nutrient but also that organism’s tolerance to the environment. Optimal and minimal conditions exist.
What differentiates eurytypic organisms from stenotypic organisms?
Eury: grow within a wide range of a specific condition (ex: temp)
Steno: grow only in a narrow range of a specific condition (ex: temp)
What is meant by “quorum sensing”?
Cells reach a certain density and can start expressing proteins which can affect the surrounding population.
How much ferric iron is contained in the human body?
Only 5g!
What is “diauxic growth”?
Cell growth in 2 phases. Caused by the organism switching from one nutrient source to another more beneficial one.
What are 4 examples of environmental factors that might affect bacteria growth?
- Water
- Sodium
- Light
- Temperature
In what 3 main ways does temperature affect the growth and survival of organisms?
- Rate of chemical reactions
- Denaturation of proteins
- Climate
At what temperatures do mesophilic bacteria thrive?
~ 39C
At what temperatures do thermophilic bacteria thrive?
~ 60C
At what temperatures do hyperthermophilic bacteria thrive?
~88C or even greater
At what temperatures do psychrophilic bacteria thrive?
~ 4C
What temperature range do pathogenic bacteria usually prefer?
Mesophiles who prefer temperatures in a narrow range ~37C (the normal temp of the human body).
Describe the oxygen relationship of a bacteria which is an “obligate aerobe”.
Requires oxygen for aerobic respiration.
Describe the oxygen relationship of a bacteria which is a “facultative aerobe”.
Oxygen helpful, but not required. Can do aerobic or anaerobic respiration, as well as fermentation.
Describe the oxygen relationship of a bacteria which is a “microaerophile”.
Requires oxygen for aerobic respiration, but at lower than atmospheric levels.
Describe the oxygen relationship of a bacteria which is “aerotolerant”.
Oxygen has no effect. Uses fermentation for energy.
Describe the oxygen relationship of a bacteria which is an “obligate anaerobe”.
Oxygen harmful or lethal. Can do anaerobic respiration and fermentation.
What sorts of energy metabolisms did organisms likely use prior to the appearance of oxygen?
Organisms where likely chemoautotrophic or fermentative.
How would you define a biological population?
All organisms of the same species living in the same place and time.
How does statistics define a population?
“The totality of individual observations about which inferences are to be made, existing anywhere within a defined sampling area and time.”
What 3 strategies have prokaryotes used to adapt to higher temperatures?
- Changing hydrophobic interactions
- Changing hydrogen bonding
- Adding more salt bridges
What did bacteria use to create energy before there was water?
Sulfur.
What differentiates a stable population from an unstable one?
Stable: population does not change over time
Unstable: population fluctuates over time according to other factors
What are examples of tools which can be used to count cells?
- Microscope (EM or light)
- Epifluorescence
- Petri dishes
- Spectrophotometer
- Quantitative PCR
What are the 6 growth phases of a bacterial population as described by Monod’s experiments?
- Lag
- Acceleration
- Exponential
- Retardation
- Stationary
- Declining
In bacteriology, which phase is used to define a microbial population?
The exponential phase. A population is described by its constant rate of growth rather than an actual count.
What effects do mixing populations in natural systems have on population growth and survival?
Interactions can have positive, negative, or no effect on growth and survival.
What is the definition of a biological community?
A system of organisms living together and linked by the effect they have on each other and their shared environment.
Define “neutralism”.
Lack of interaction between two populations.
Define “commensalism”.
One organism lives off the leftover nutrients of another.
Define “synergism”.
Two populations both benefit from a non-obligatory relationship.
Define “mutualism”.
Two populations benefit each other and depend on one another for survival.
Define “competition”.
Two populations use the same limiting resource. Both are negatively affected.
Define “amensalism”.
One population produces a substance toxic to competing populations, thus gaining an advantage.
What does the competitive exclusion principle stipulate?
That two populations cannot occupy the same niche. One will out-compete and eliminate the other.
Define “parasitism”.
One population steals nutrients from another, indirectly harming it.
Define “predation”.
One population consumes members of another for energy.
What is an example of organisms living in a mutualistic (symbiotic) relationship?
Cyanobacteria/algae and lichen co-exist to form lichen. Rhizobium fixes nitrogen for plants in return for nutrients.
What is an example of a way the competitive exclusion principle has been used in epidemiology?
The PCV-7 vaccine was introduced in BC to out-compete streptococcus pneumoniae.
What is an example of an organism which exhibits amensalism?
Penicillium produces beta-lactam which prevents the growth of nearby bacteria.
What differentiates an ectoparasite from an endoparasite?
Ecto: remain outside the cells of the host
Endo: penetrate into the cells of the host
What is the term used to describe a virus which targets bacteria?
A bacteriophage.
What is an “r-strategist” organism?
Organisms which favour rapid reproduction and low investment in offspring. Tend to be small and have short lifespans.
What is a “k-strategist” organism?
Organisms which invest heavily in offspring and favour survival. Tend to be larger and have longer lifespans.
What kinds of biological gradients exist which can drive population succession?
- Altitude
- Depth
- Fresh>salt water
- etc.
What is the definition of an ecosystem?
A community and its environment treated together as a functional system of a complementary relationship, and transfer/circulation of energy and matter.
What is the smallest unit used in ecology?
An ecosystem.
What are the 4 phylodynamic categories of RNA viruses?
- Short infection w/ strong cross immunity
- Short infection w/ partial cross immunity
- Infection w/ immune enhancement
- Persistent infection
Who developed the Ro # for vaccinations? When?
Robert May and Roy Anderson in the late 80s.
When was smallpox eradicated?
1980.
What is meant by a “nosocomial disease”?
A disease that is transmitted at the hospital.
What type of infectious agent is gonorrhea?
Bacteria.
What type of infectious agent is streptococcus pneumonia?
Bacteria.
What type of infectious agent is malaria (plasmodium falciparum)?
Protozoa.
What mutation caused some people to not contract HIV when exposed? Which gene is it a part of?
Delta 32, in the CCR5 gene.
What type of infectious agent is HIV?
Virus.
What type of infectious agent is influenza?
Virus.
What type of infectious agent is Creutzfeldt-Jakobs?
Prions.
What are the 2 proteins on the influenza virus?
- Hemagluttinin
2. Neuraminidase
Which of the 2 inlfuenza proteins is the better target for treatment?
Hemagluttinin.
What is the function of Hemagluttinin in the influenza virus?
Attaches to salycilic acid and allows viral genome insertion.
What is the function of Neuraminidase in the influenza virus?
Allows the virus to detach from the host cell.
How did Thomas Brock advance bacterial research?
He showed that bacteria could grow at extremely high temperatures by analyzing colonies from geysers in Yellowstone.
What differentiates the IPV and OPV vaccines?
IPV: developed by Salk, injected
OPV: developed by Sabin, oral (can lead to paralysis)
What is the name of the iron carriers in cyanobacteria and bacteria?
Siderophores, which solubilize iron for transport.
What is enterobactin?
A siderophore. Transports iron and attaches to receptor, allowing bacteria to uptake iron.
Describe Martin’s experiment.
Dumped iron into sea water and observed rampant chlorophyll growth.
Hemacytometer is for blood cells what _____ is for bacteria.
Petrof-Hauser.
At what salinity do nonhalophilic bacteria thrive?
Can’t tolerate any salt.
At what salinity do halotolerant bacteria thrive?
Need a little salt.
At what salinity do halophilic bacteria thrive?
Like moderate levels of salt.
At what salinity do extreme halophilic bacteria thrive?
Like being salty AF.
Place the following in order of when they increase during bacterial growth: Cell numbers, DNA, RNA, Proteins.
First RNA increases, then proteins, then DNA, and finally cell numbers.
