Origins of Life, Evolution, and Classification of Organisms

Early Earth Conditions

• Age of Earth: Approximately 5 billion years old.
• Early Conditions:
  • Referred to as prebiotic or sterile.
  • Characterized by extreme heat, volcanic activity, frequent asteroid impacts, electrical storms, and dust storms.
  • Life began around 1 billion years after Earth's formation, roughly 3.5 billion years ago.

Evolutionary Timeline

• Large Macroscopic Organisms: Appear about 900 million years ago.
• Dinosaurs: Relatively recent in Earth's history compared to initial life forms.
• Humans: Present for a few hundred thousand years, considered a blink in geological time.

Primordial Soup Theory

• Chemical Composition:
  • Abundance of molecules such as iron sulfide, hydrogen sulfide, carbon dioxide, potassium cyanide, carbon monoxide, and ammonia.
  • These chemicals are believed to have provided conditions for the emergence of complex life.

Miller-Urey Experiment

• Conducted in 1952 by Stanley Miller and Harold Urey.
• Experimental Setup:
  • Used a flask filled with chemicals like methane, hydrogen, ammonia, and water.
  • Simulated early Earth conditions with electrical sparks and similar temperatures.
• Results:
  • Conversion of 10-15% of carbon into organic molecules related to life.
  • Reanalysis after 2007 revealed over 20 different amino acids.
  • Similar experiments have produced nucleotides, building blocks of DNA and RNA.

Hypotheses on Life's Origin

• RNA Hypothesis: Suggests that ribonucleic acid (RNA) played a critical role in the assembly of biological molecules into living organisms.

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Next Steps

• Review of a video on RNA's role in the origin of life.