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Lecture 3

BIOL 215 Lecture Notes - Lecture 3: Magic 2Ch, Bacteriochlorophyll, Magnetite


Department
Biology (Sci)
Course Code
BIOL 215
Professor
Neil Price
Lecture
3

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BIOL215 Lecture 3 Notes
The final step in the evolution of cells must have been the formation of an outer membrane that
encased the nucleic acids and proteins
Believe that precursor molecules which could form abiotically could have included fatty acids
Fatty acids (palmitic acid, oleic acid) are hydrocarbons
Understand the hydrophilic and hydrophobic components in a molecule (bimolecular layer)
See example of micelles fuse to form vesicles
How might the association between nucleic acids and membranes lead to the formation of a stable
entity that displays cellular behavior?
1. Osmotic stress
2. Creation of an electrochemical gradient (energy)
A theory of life's beginnings:
1. Prebiotic chemicals react to form small organic molecules in a watery environment ("soup")
2. Polymerization and dehydration ("crepes") form nucleic acids and proteins
3. RT copies RNA into complementary DNA, which replicates
4. DNA replicates; RNA from DNA builds proteins. lipids form spheres
5. Self-replicating system enclosed in a permeable protective lipid sphere
The hypothesis for the origin of metabolism (see diagram):
Precursor cells (progenotes) use A as energy source
As A is depleted those cells that evolve an enzyme to convert B into A thrive
Natural selection would favour progenotes that used diverse substrates
A popular view is that life may have first evolved in the deep sea near hydrothermal vents (boundaries
between plates and the Earth's crust)
UV radiation would have destroyed most macromolecules in the sea surface - ozone was not
created until O2 was produced
Clays (serve as template upon which the nucleic acid precursor aligned) and metal catalysts
All organisms have similar requirements for life:
Liquid water
Water accounts for 50-90% of an organism's mass
Is a universal solvent; stabilize other molecules via H-bonding, polar molecule allows for
bonding
All chemical reactions necessary for life occur in water
Elements which make up essential biomolecules
An energy source
Energy is used to assemble elemental elements/building blocks (i.e. C, N, Fe) into complex
molecules for the construction of organisms; motility; acquire other resources...
Organisms use one of 3 main sources of energy:
Light (photosynthesis)
Organic molecules (breaking bonds to extract bond energies)
Inorganic molecules (chemosynthesis)
Organisms can be classified by how they obtain energy and carbon - C is one of the most
important elements used for growth
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