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