Chapter 25 Biology History of Life on Earth Flashcards

Speciation, Mass Extinction Events - anything that offers new contributions to diversity of life

4.5 billion years

3.5 billion years old

Abiotic (nonliving) synthesis of small organic molecules like amino acids and nucleotides followed by the joining of these small molecules into macromolecules with proteins and nucleic acids. Then these macromolecules were packaged into protobionts, which led to the origin of self-replicating molecules that eventually made inheritance possible.

These are droplets w/ membranes that maintained an internal chemistry different from that of their surroundings. Filled with small molecules.

3.9 billion years ago

These two scientists suggested early Earth's atmosphere was reducing (electron-adding) and that organic compounds could have formed from simple molecules. Coupled with UV radiation and light energy, early oceans would have been solutions for organic molecules, or "primordial soups" (1920's)

These two tested a hypothesis from thirty years earlier (in the 1920's) by making an apparatus that simulated the conditions of what ppl believed was on early Earth and yielded amino acids found in organisms today.

If atmosphere wasn't reducing, underwater ocean volcanoes could have produced organisms because the regions are rich in sulfur and iron compounds important in ATP synthesis

These also carried amino acids similar to those produced in Miller-Urey experiment, like carbonaceous chondrites.

Since having only some amino acids isn't enough for life, amino acids formed combinations to create these things, complex and cross-linked, which acted as weak catalysts for reactions on early Earth

Accurate replication and metabolism

DNA, enzymatic machinery, and nucleotides (even though Miller-Urey did not produce nucleotides)

Simple reproduction, metabolism, homeostasis/ maintaining internal chemical environment

This plays a central role in protein synthesis and can carry out a number of catalytic functions, according to Altman and Cech (Yale). Early earth could have been entirely just this at one point.