Biology 1202B Lecture Notes - Louis Pasteur, Reducing Atmosphere, Clay Minerals

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Published on 19 Apr 2013
School
Western University
Department
Biology
Course
Biology 1202B
Origin of Life
Summary
Characteristics of Living Things
1. Tend to be complex and highly organized
2. Ability to take energy from the environment and change it to other forms
3. Tend to be homeostatic – regulate bodies/internal structures
4. Respond to stimuli
5. Reproduce by making copies
6. Tend to grow and develop
7. Adapt/Evolve with changes in the external environment
Panspermia
Asteroids/comets could have brought organic matter to earth (can’t be sure it is
not a product of some geological process rather that an actual fossilized structure)
Universe formed 15 billion years ago, Earth 4.6, oldest fossils 3.5, and Eukaryotic
fossils 2.2
Spontaneous Generation
Louis Pasteur living matter cannot generate spontaneously from non-living matter
Conditions were much different on early Earth (boiled beef broth experiment)
Cell Theory
1. All organisms are composed of one or more cells
2. The cell is the smallest unit with all the properties of life
3. Cells arise only from growth and division of preexisting cells
Oparin-Haldane
Organic molecules could be made in the absence of life (energy from UV light,
lightning, volcanoes)
oEarly Earth had a reducing atmosphere (lots of electrons for reactions to
occur)
Early Atmosphere
Reducing atmosphere (no free oxygen), free hydrogen and hydride (CH4, NH3,
H2O), energy from sun and lightning (no ozone layer), hotter surface temperature
Miller-Urey Experiment
Used: boiling water, continuous spark from electrodes, gases (CH4, NH3, H20, H2)
and a condenser
Obtained: urea, amino acids, lactic acid, formic acid, acetic acid, nucleotides
oProved that reducing atmosphere is probable for origin of life
Polymers
Condensation reactions – when components of water molecules are removed
oPeptide bonds with amino acids/phosphodiester bonds with nucleotides
Polysaccharides (F20-F23) – monosacchaarides linked together (glucose, ribose,
etc.)
Proteins (F24-F28) – amino acids (20)
Nucleic Acids (F29-31) – Nucleotides (5)
Catalysts
Molecules adsorb to clay mineral particles (become concentrated/stick to surface
particles)
Clay particles may have been used as catalysts in formation of small polymers
(50aa)
oEnzymes now serve this function
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