Origins of Life and Abiogenesis

Vocabulary flashcards covering the key terms, hypotheses, and timeline of abiogenesis and the early history of life on Earth.

Abiotic factors

The non-living components of an ecosystem, which include wind, water, atmosphere, temperature, soil, and sunlight.

Abiogenesis

The process by which the first life developed from non-living organic molecules.

Abiotic synthesis

The spontaneous creation of organic molecules from inorganic components.

Four requirements for abiotic synthesis

Low oxygen (electronegative and responsible for breaking bonds), a source of energy, chemical components (CHON), and lots of time.

Prebiotic Soup Hypothesis

A hypothesis proposed by Oparin and J.B.S Haldane in the 1920s stating that life formed near Earth's surface through the spontaneous formation of monomers.

Iron Sulphur World Hypothesis

A hypothesis proposing that life formed at cracks on the ocean floor at hydrothermal vents, where hot water and minerals were released and iron acted as a catalyst.

Four steps of abiogenesis

1. Abiotic synthesis of monomers; 2. Formation of macromolecules; 3. Formation of protocells; 4. Appearance of self-replication.

Vesicle

A fluid-filled compartment surrounded by a membrane-like structure that forms spontaneously from lipids in water.

Protocells

Aggregates (clumping) of abiotically produced organic macromolecules that exhibit attributes of living cells but lack a mechanism of heredity.

RNA-Peptide World Hypothesis

A hypothesis stating that the first replicating systems used RNA to store and copy genetic information, with a limited role for polypeptides and DNA incorporated later.

Ribozymes

RNA molecules with enzymatic properties that can cleave RNA and catalyze RNA polymerization.

The first cells

Prokaryotes lacking a nucleus that were anaerobic (did not use oxygen) and heterotrophic (obtained organic molecules from the environment).

Autotrophy

The process of using energy from sunlight to create food, which first released sulfur and later released oxygen by splitting water (cyanobacteria).

Oxygen Apocalypse

An event occurring approximately $2.5\text{ bya}$ characterized by a rise in atmospheric oxygen due to oxygenic photosynthesis, causing a mass extinction and banded iron formations.

Banded Fe Formation

Iron oxide formations produced in rocks as a consequence of the oxygen released during the Oxygen Apocalypse.

Aerobes

Organisms capable of aerobic respiration that became prevalent after the Oxygen Apocalypse due to the benefit of higher ATP yield.

Eukaryotes

Cells containing a membrane-bound nucleus and organelles that appeared at least $1.8\text{ bya}$ and were generated through endosymbiosis.