Evolution and Origins of Life Notes

Theories about the beginnings of life include primordial soup theory, which suggests that life originated from a mixture of organic compounds in the early Earth's oceans, and hydrothermal vent hypothesis, proposing that life began at the ocean floor around mineral-rich vents.

Unit #6: Evolution, Natural Selection, and Taxonomy

  • Focus on evolution, natural selection, and taxonomy.

Origins of Earth

  • Unit introduction.

About Evolution

  • Shifting focus to evolution and how populations have evolved.

  • Studying DNA helps understand relationships between organisms (past and present).

What is Evolution?

  • Evolution is the change in heritable traits through generations - change over time!

  • Evolution occurs in populations, not individual organisms!

How Have Organisms Changed?

  • First cells were anaerobic (require no oxygen), about 3.8 billion years ago, due to little oxygen on Earth.

  • Photosynthetic prokaryotes (cyanobacteria) evolved, using sunlight to produce food, with oxygen as a waste product.

  • Earth's atmosphere became filled with oxygen, allowing aerobic (require oxygen) organisms to evolve.

  • This led to the evolution of eukaryotic, complex multicellular organisms.

  • Earth and moon are about 4.6 billion years old.

The Endosymbiotic Theory

  • Theory: Eukaryotic cells formed from symbiotic relationships among different prokaryotic organisms.

  • Prokaryotes using oxygen to generate ATP evolved into mitochondria.

  • Prokaryotes carrying out photosynthesis evolved into chloroplasts.

The Endosymbiotic Theory (cont.)

  • Prokaryotes: mostly autotrophic (some heterotrophic).

  • Ancestral prokaryotes were strictly heterotrophs until development due to exposure to photosynthetic organisms.

Spontaneous Generation vs. Biogenesis

  • Spontaneous generation: Living organisms can be produced from non-living matter.

Spontaneous Generation vs. Biogenesis (cont.)

  • Biogenesis: Living organisms can only arise from other living organisms.

  • Francesco Redi's experiment disproved spontaneous generation.

Francesco Redi's Experiment

  • Open container: Maggots formed in meat.

  • Cork-sealed container: No maggots formed in meat.

  • Gauze-covered container: No maggots formed in meat.

Prehistoric Life: Miller-Urey Experiment

  • Miller-Urey experiment: To determine if creation of macromolecules was possible in pre-existing life.

  • Macromolecules: Building blocks of life.

Miller-Urey Experiment Setup

  • Key components include: Water vapor, CH<em>4CH<em>4, NH</em>3NH</em>3, H<em>2H<em>2, Electrode, COCO, Condenser, H</em>2OH</em>2O, Cooled water containing organic compounds, Sample for chemical analysis, Cold water

Miller-Urey Experiment Details

  • Flask with water = Earth's water.

  • Bunsen Burner = Heat sources on Earth.

  • Electrode = Lightning.

  • Gases added (water vapor, ammonia, methane, nitrogen) = Early Earth atmosphere.

Miller-Urey Experiment Results

  • Amino acids formed in the collected sample.

  • Demonstrated the possibility of abiogenesis: Spontaneous origin of life from non-living (inorganic) matter.

  • Miller-Urey Experiment Assignment.

  • Look at interims!