Origin Of Life Flashcards
What is a polythetic classification?
PICERAS - program, improvisation, compartmentalisation, energy, regeneration, adaptability, seclusion
What is NASA’s definition of life?
Life is a self-sustained chemical system capable of undergoing Darwinian evolution.
What are specific features of Terran life?
Metabolism and heredity/variability.
What characterizes metabolism in Terran life?
Thermodynamically open system in disequilibrium.
What is the balance in heredity/variability?
Balance between fidelity and variability (random variation).
What is the role of protein catalysts in life?
Presence of protein catalysts.
What is DNA’s role in life?
DNA as the depositary of information.
How do complex molecules form in life?
Makes complex molecules from simple monomers taking advantage of the covalent binding properties of C, H, N, O, P, and S.
What is the significance of water in life?
Specific interactions with water - need of compartmentalisation.
What is biochemical retrodiction?
Reconstructing evolutionary precursors to extant biochemical pathways.
What is the Pentose pathway’s role in metabolism?
Catabolic and anabolic reactions are intertwined.
What was primordial metabolism composed of?
A mixture of autotrophs and heterotrophs.
What is the RNA world hypothesis?
Life started with a population of replicators and later became cellular as descendants of its molecules became enclosed in a membrane.
Why is RNA considered a better candidate than DNA for early life?
RNA is more reactive than DNA.
What are ribozymes?
Catalytic RNAs discovered, such as the Hammerhead ribozyme (Pdb:379d).
What are some reasons RNA is preferred over DNA?
DNA is less reactive due to its double helix and deoxyribose.
What are some examples of RNA derivatives?
RNA involved in translation, splicing, priming/synthesis of DNA, and RNA derivatives in cofactors.
What are some cofactors that are relics of the RNA-world?
Acetyl-CoA and Vitamin B12.
What is necessary for replicators to exist?
A primordial metabolic network.
What is abiogenesis?
A natural process by which life arises from simple organic compounds.
What did Charles Darwin suggest about the origin of life?
The spark of life may have begun in a warm little pond with all sorts of salts, light, heat, electricity, etc.
What did Alexander Oparin propose about the origin of life?
The spontaneous generation of life occurred under strongly-reducing conditions.
What did John BS Haldane independently propose?
Similar ideas concerning the conditions required for the origin of life on Earth.
What were the results of the Miller-Urey experiment in 1953?
> 10% total C converted into organic compounds, 2% of which were amino acids.
What was the composition of the primordial atmosphere?
Mildly reducing, with no ozone, HCN, CO2, N2, H2S, H2O, and abundant energy.
What evidence supports the idea that organic compounds can exist in space?
Meteorites as a source of organic compounds.
What is panspermia?
The hypothesis that life exists throughout the universe, distributed by meteoroids, asteroids, comets, and planetoids.
What is the significance of hydrothermal systems for early life forms?
50-70 degrees Celsius, compatible with many biochemical reactions.
What is the role of chemical disequilibrium in the origin of life?
Essential for all life forms.
What is the importance of the proton motive force?
Essential for all life forms.
How does chemical disequilibrium relate to bioenergetics?
Life was able to harness energy from spontaneous reactions to fuel biosynthetic pathways.
Why is compartmentalisation important?
Maintenance of a proton motive force and separation of reactants and products.
How do vesicles form from prebiotic molecules?
Vesicles assemble spontaneously.
What are the steps from prebiotic chemicals to protocells?
- Abiotic synthesis 2. Joining of monomers 3. Creation of primordial metabolic networks 4. Formation of protocell communities.
