EEMB 3 Flashcards
Gaia Hypothesis
Earth is a living entity and it regulates and maintains climate and atmosphere at an optimum level.
When were the earliest forms of life found on Earth?
3.5 - 3.8 bya
What are the essential characteristics of life?
- Membranes
- Aqueous system
- Monomers to macromolecules
- Information carriers (RNA & DNA) and translation apparatus
- Energy storage and flow
- Catalysts
What did Francesco Redi discover?
Though his experiments with exposed and sealed jars of meat, he found that life generates life.
Louis Pasteur
Discovered that airborne microbes are responsible for the decomposition of organic matter though his experiment with curved tubes leading to a flask.
- Pasteurization
- Contributed to theory and practice of vaccination.
Panspermia Hypothesis
The theory that life exists and is distributed throughout the universe in the form of germs or spores, and that life on Earth originated through extraterrestrial means.
Chemical Evolution Hypothesis
Origin of life can be viewed as four overlapping stages:
- Nucleotides and Amino Acids before cells.
- Nucleotides and AA’s polymerize → DNA, RNA and proteins.
- Polymers enclosed in membranes.
- Evolution of cellular properties.
Extraterrestrial Input Hypothesis
Organic matter and water brought to Earth via asteroid and comet collisions.
Reducing Atmosphere Hypothesis
Or Chemical Evolution
- Hypothesis formed in the 1920’s by Oparin and Haldane whereby nucleotides and aa’s occured naturally.
- Volcanic gasses created a strongly reducing atmosphere.
- Little or no O2
Miller-Urey Experiment
Discovered that in a reducing atmosphere containing methane, carbon dioxide, ammonia, hydrogen and nitrogen, but without oxygen–nucleotides and amino acids naturally form.
Hydrothermal Vent Hypothesis
Temperature gradients and plume chemistry led to the formation of organic molecules.
Changes in living organisms are a result of what two interactive processes?
- Genetic Exchange
- Environmental change
How did macromolecules form from monomers without the aid of enzymes?
Condensation reactions (Terminal OH and H on separate monomers react to combine and leave water as byproduct).
What are three plausible location for initial polymerization without the aid of enzymes?
- Solid mineral surfaces
- Hydrothermal vents
- Hot pools
Protobionts
Aggregrate of abiotically produced organic molecules that can have metabolism.
Coacervate
A tiny spherical droplet of assorted organic molecules (specifically, lipid molecules) which is held together by hydrophobic forces from a surrounding liquid. Cannot reproduce.
What role did RNA play in a pre-DNA world?
RNA acted as both:
- Information carrier, and;
- Catalyst
Through fossils’ _____ relationship, people can determine the relative ages of fossils.
stratigraphic
- Similar types of fossils found within strata in widely separated parts of the earth.
- Major changes in fossil types in the rock strata used to define time periods.
Absolute dating is determined through what method?
Radioactive decay
- Radioactive isotope decay over regular equal periods of time.
- If you know how much isotope existed at the beginning and you know how much remains you can calculate the age of the sample.
What are the 5 geologic and biogeochemical changes that affected extinction and evolution?
- Continental drift - sea level drop
- Climate change
- Volcanic activity
- Unidirectional flux in O2
- External events
What are three common features that all microbes share?
- They live in water-rich environments
- They’re a food source for higher trophic levels.
- All are small!
What are some important consequences of microbes’ small size?
- Small size leads to high surface area to voume ratio.
- Higher proportion of metabolically active body components.
- Higher growth rates.
Although phytoplankton account for only 0.2% of all living plant matter on earth, they are responsible for __% of the earth’s photosynthetic activity.
45%
_____ _____ bacteria are the base of the food web around hydrothermal vents.
sulfur oxidizing
Of all the biogeochemical cycles, the _____ cycle is the one most intimately and throughly associated with microbes.
nitrogen
Van Leeuwehoek
Was the first scientist to observe bacteria and protists, though the use of a crude microscope.
Magnification
Produces a larger image but provides no additional detail.
Resolution
The distance between 2 objects that allows one to discern them as separate; increased resolution causes increased detail and information.
Robert Koch
- “The Father” of medical microbiology.
- Developed the pure culture technique–assumed colonies with different shapes and colors were derived from different microbes.
- His postulates led to his “germ theory,” proving that diseases were caused by microbes.
Alexander Flemming
Discovered penicillin through fungal spores that grew on his uncovered petri dish(es).
Sergei Winogradsky
An environmental microbiologist who was the first to develop idea of chemolithotrophy.
Chemolithotrophy
Organisms obtain their energy from the oxidation of inorganic compounds and use CO2 as their carbon source…they are autotrophs.
Martinus Beijerinck
An environmental biologist who discovered enrichment cultures.
- Set up culture with all inorganic compounds except Nitrogen; if microbes were to grow they would have to fix N.
Kary Mullis
Won the Nobel Prize in Chemistry in 1993 for creating the now widely-used Polymerase Chain Reaction.
Thermus aquaticus
A microbe discovered by environmental microbiologists Thomas Brock and Hudson Freeze to contain Taq polymerase, a heat stable polymerase.
Norm Pace
Created cultivation independent techniques
- 16s rRNA gene clone library construction
What are the four steps to identifying an organism via rRNA genes?
- Isolate plasmids from clones
- Sequence rRNA gene ligated in plasmid
- Align sequence data to assess variability
- Construct phylogenetic relationship
Prokaryotes have approximately _____ as much DNA as eukaryotes.
1/1000
What are the three mechanisms for prokaryotic genetic recombination?
- Transformation: the genetic alteration of a cell resulting from the direct uptake, incorporation and expression of exogenous genetic material
- Conjugation: the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells.
- Transduction: the process by which DNA is transferred from one bacterium to another by a virus
How do you differentiate between bacteria and archaea cell membranes?
Bacteria:
Phospholipid bilayer w/fatty acids.
Ester linkage.
Peptidoglycan cell wall (muramic acid).
Archaea:
Phospholipid bilayer w/o fatty acids, isoprene instead. Some have monolayer.
Ether linkage.
No peptidoglycan
What are the differences between gram + and gram - cell walls?
Gram + : Simpler cell wall
Less physiologically diverse
Can produce exotoxins
Gram - :More complex, lipopolysaccharides (LPS) attached.
Can produce endotoxins
Anobolism
The biosynthensis of new macromolecules from monomers and/or polymers and an energy source (like ATP).
