Creating Life in the Lab

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The great optimism of the 1950's


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Watson & Crick and DNA, Miller-Urey, Oparin-Haldane hypothesis

Great optimism about working out the details of "abiogenesis"

Quandries of 2013 as all paths explored have encountered huge barriers

Creating Life in the Lab
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Simple Life?


Eukaryotic Cell

Prokaryotic Cell

"The cell is a simple homogeneous globule of plasm." T. H. Huxley, 1869, "Darwin's bulldog"

Definition of life from Stuart Pullen's "Intelligent Design or Evolution":
"Life is a system of chemicals possessing molecular knowledge and a mechanism to implement this knowledge in such a way that the system can survive long enough to replicate itself. At a minimum:

  • Store molecular knowledge.
  • Implement this knowledge.
  • Tap a plentiful energy source to power the implementation.
  • Synthesize any biological molecules required for replication that are not plentiful in the primordial soup."

Rana "Creating Life in the Lab" - Defining life

Life obeys the laws of chemistry and physics

Characteristics:

  1. Life Is Organized
  2. Life Is Chemically Distinct from Its Environment
  3. Life Is Homeostatic
  4. Life Takes Energy and Matter from the Environment and Transforms Them
  5. Life Responds to Stimuli from the Environment
  6. Life Reproduces
  7. Life Is Adapted to Its Environment

Elements explored in Fuz Rana's The Cell's Design.

Creating Life in the Lab
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Miller-Urey Experiment

In 1952 graduate student Stanley Miller carried out his now famous spark-discharge experiment designed to test the Oparin-Haldane hypothesis that biological molecules as the precursor to life could have been created by lightning discharges in the atmosphere of the early Earth.

Miller did find that the discharge could produce amino acids. Including the analysis of some of his experimental chambers after his death, there were about 20 different amino acids in the residue left by the process.

Finding a pathway to amino acids was indeed a crucial step toward understanding life chemistry since they are used to build up proteins in cells by the processes of transcription and translation. The Miller-Urey experiment along with the discovery of DNA structure did lead to great optimism in the 1950's about discovering a chemical pathway to life.

Creating Life in the Lab
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Oparin-Haldane Hypothesis

Oparin (1924) and Haldane (1929) independently hypothesized a scenario for the building of the chemical building blocks of life. Oparin in 1936 discussed further steps that would lead to an origin of life from non-living material, which is popularly called "abiogenesis". The illustration at left summarizes the steps of what has been called the Oparin-Haldane Hypothesis for abiogenesis.

Creating Life in the Lab
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We might need a little more detail on those last steps

The Oparin-Haldane Hypothesis suggests the action of natural selection in the stages leading from vesicle encapsulation of the biological building blocks to the first living cell. But before the existence of a self-replicating entity, the idea of natural selection does not seem to apply.

Phospholipids and some other compounds do spontaneously form membranes and even vesicles, but most of those molecules that we observe doing that are themselves of biological origin, so they form a chicken-and-egg problem.

The scenario depicted here suggests that nature spontaneously overcame the hurdles of creating a metabolism and the problem of self-replication. Current research follows either the metabolism-first or replicator-first scenarios, and both have encountered major hurdles.

Creating Life in the Lab
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