History of Microbial Ecology, Origin of Life, and Being Small

Question 1

How can you increase flow

Answer 1

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.

Question 2

What is Reynolds number

Answer 2

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.

Question 3

What is life like at high Reynolds Numbers (more than 1000)

Answer 3

It is our world, inertial forces much more important than viscous forces.

Question 4

What is life like at low Reynolds numbers (less than 1000)

Answer 4

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.”

Question 5

Should bacteria swim?

Answer 5

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.

Question 6

Why don’t bacteria swim

Answer 6

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.

Question 7

What is Stokes’ Law

Answer 7

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.

Question 8

What are the benefits for microorganisms in being small

Answer 8

The ability to absorb nutrients, and excrete toxins/waste faster. They grow at a fast rate.

Question 9

What are the consequences of being small

Answer 9

With such a high number of cells, we have a higher replication/turnover rate. This leads to even rarer events happening often.

Question 10

Who is Antonie van Leewenhoek

Answer 10

Dutch amateur microscope builder, and was the first to observe “animalcules.”

Question 11

How was pure culture isolation discovered

Answer 11

Initially developed by Fannie and Hesse for the agar and Richard Petri who developed the Petri dish

Question 12

Why don’t all bacteria grow in culture

Answer 12

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).

Question 13

What is enrichment culture

Answer 13

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.”

Question 14

What is the Winogradsky Column

Answer 14

Founded by Sergei Winogradsky who discovered lithotrophy, nitrifying bacteria and other big concepts in biogeochemistry

Question 15

Who is Carl Woese

Answer 15

American microbiologist. First to use rRNA genes sequences for taxonomy. Discovered Archaea

Question 16

What was Louis Pasteur’s experiment

Answer 16

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.

Question 17

What is the Primordial Soup Theory

Answer 17

1. Primordial Atmosphere - Methane, Ammonia, Hydrogen, and Water Vapour which leads to energy
2. Energy - Lightning, Volcanic heat, UV light, and other sources of radiation which leads to organic molecules
3. Organic molecules form amino acids and nucleic acids which led to living organisms
4. First living organisms arise.

Question 18

What was the Miller-Urey Flask Experiment

Answer 18

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

Question 19

What is the Genes-First Model

Answer 19

Genes lead to proteins

Question 20

What is the Metabolism-First/Dual-Origin Model

Answer 20

Metabolism leads to genes

Question 21

What is the Membrane-First Model/Dual-Origin Model

Answer 21

Membrane leads to genes/metabolism

Question 22

What shows that the RNA World was possible

Answer 22

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

Question 23

What shows that the Metabolism-First Models were possible

Answer 23

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.

Question 24

What shows that the Membrane first/Dual Origin Model is possible

Answer 24

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.

Question 25

What shows that the “everything first” model is possible

Answer 25

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.

Question 26

What is a Progenote

Answer 26

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.

Question 27

What is Urkayote

Answer 27

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.

Question 28

What is the evidence that there was a urkaryote

Answer 28

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

Question 29

What is the Urkaryote like

Answer 29

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