History of Microbial Ecology, Origin of Life, and Being Small Flashcards
How can you increase flow
Increase the speed of the flow, increase the diameter of pipe, increase the density of liquid, decrease the viscosity of liquid, streak will become dispersed and cause turbulent flow.
What is Reynolds number
The Reynolds number is the ratio of inertial forces to viscous forces within a fluid which is subjected to relative internal movement due to different fluid velocities.
What is life like at high Reynolds Numbers (more than 1000)
It is our world, inertial forces much more important than viscous forces.
What is life like at low Reynolds numbers (less than 1000)
Viscous forces much more important than inertial forces. Mixing is very difficult. Inertia is nearly non-existent - stops immediately upon removal of force. Drag increases significantly around solid objects - more difficult to move. Describes as “swimming in asphalt on a hot summer day.”
Should bacteria swim?
Diffusion brings food to it. In the real world most microorganisms are not moving around. They let the food supply come to them or carried away from them.
Why don’t bacteria swim
To increase food supply by 10%, one would have to swim at 700 body lengths per second (equivalent to a human running at ~2863 miles/hours). Thrashing around doesn’t mix water or bring more nutrients. ONLY reason to swim and look for a more concentrated food source.
What is Stokes’ Law
An expression describing the resisting force on a particle moving through a viscous fluid and showing that a maximum velocity is reached in such cases.
What are the benefits for microorganisms in being small
The ability to absorb nutrients, and excrete toxins/waste faster. They grow at a fast rate.
What are the consequences of being small
With such a high number of cells, we have a higher replication/turnover rate. This leads to even rarer events happening often.
Who is Antonie van Leewenhoek
Dutch amateur microscope builder, and was the first to observe “animalcules.”
How was pure culture isolation discovered
Initially developed by Fannie and Hesse for the agar and Richard Petri who developed the Petri dish
Why don’t all bacteria grow in culture
Cellular damage leaves the cell viable but not culturable. Viral infection and lysis. Their environmental requirements can not be reproduced in the laboratory. Chemical dependency (metabolic consortia where a growth component is required). They are social (requires the presence of other bacteria physically or for communication).
What is enrichment culture
Developed by Martinus Beijerinck a dutch microbiologist. The founder of virology (tobacco mosaic virus), discovered nitrogen fixation, discovered sulfate reduction. He is known as the “father of environmental microbiology.”
What is the Winogradsky Column
Founded by Sergei Winogradsky who discovered lithotrophy, nitrifying bacteria and other big concepts in biogeochemistry
Who is Carl Woese
American microbiologist. First to use rRNA genes sequences for taxonomy. Discovered Archaea
What was Louis Pasteur’s experiment
He showed that beef broth could be sterilized by boiling it in a “swan-neck” flash, which has a long bending neck that traps dust particles and other contaminants before they reach the body of the flask.
What is the Primordial Soup Theory
- Primordial Atmosphere - Methane, Ammonia, Hydrogen, and Water Vapour which leads to energy
- Energy - Lightning, Volcanic heat, UV light, and other sources of radiation which leads to organic molecules
- Organic molecules form amino acids and nucleic acids which led to living organisms
- First living organisms arise.
What was the Miller-Urey Flask Experiment
Sparks created by electrode recreates lighting, water is heated to promote evaporation, condenser results in simulated rainfall, and amino acids are present in water. This sadly doesn’ t answer how life came into being
What is the Genes-First Model
Genes lead to proteins
What is the Metabolism-First/Dual-Origin Model
Metabolism leads to genes
What is the Membrane-First Model/Dual-Origin Model
Membrane leads to genes/metabolism
What shows that the RNA World was possible
Ribozymes were discovered but were inefficient, unstable and our modern RNA is most likely a remnant of this because it is inferior when compared to DNA and amino acids
What shows that the Metabolism-First Models were possible
Hot volcanic water with reduced compounds flow over minerals, leading to the formation of organic compounds and polymerization which eventually led to a metabolic cycle. Some of these reactions can occur at hydrothermal vents BUT organic molecules don’t survive long in hot water.
What shows that the Membrane first/Dual Origin Model is possible
The need to form “containers” which are vesicles are stable and can be forced to form daughters. If you add clay, formation speeds increase and clay acts as catalysts. If RNA is included, can have complete system - dual origins.
What shows that the “everything first” model is possible
Many of the basic molecules of light need the same chemical components such as UV light, simple organics, cyanide and metals - raw enzymes. These will cause “messy” syntheses which are complex mixes that can do things that simple reactions cannot do.
What is a Progenote
Earliest form of life with poor linkage between genotypes and phenotype. Metabolism, there was information but wasn’t well linked. Natural selection allowed for the higher linkages to occur and better creations.
What is Urkayote
Last common ancestor of all three major lines of descent. Many have been multiple cells with lots of horizontal gene transfer. It needs to have many characteristics because every living organism has these characteristics.
What is the evidence that there was a urkaryote
The genetic code, same limited set of amino acids and nucleic acids used. Handedness - same chirality across all forms of life. Unity in biochemistry. Universal genes
What is the Urkaryote like
Little regulation of horizontal gene transfer which allowed for any new discovery/new gene mutation rapidly spreading throughout the population. Essentially it allows for one very large genetic pool which occurs when resources become more scarce, no distinct species, allows for improvement to spread fast, went away as individual populations became more protective of genes
