Scientific Methods and Early Earth Origin of Life

Vocabulary-style flashcards covering the scientific method, water polarity, early Earth atmospheric conditions, stages of cell origin, and the Miller-Urey experiment.

Scientific Method

A standardized way of communicating discoveries that reduces subjectivity, removes bias, and separates opinion from fact.

Scientific Method Flowchart

A process diagram that begins with observations, forms a hypothesis, generates predictions ("If…then…"), tests them through observations and experiments, and determines if the hypothesis is supported or refuted.

Earth Formation (Age)

Formed about $4.6\text{ billion years ago}$ along with the rest of the solar system, initially subjected to heavy bombardment by rock and ice.

Surface Water Retention (Cooling Period)

A period between $3.8\text{ and }4.2\text{ bya}$ when Earth cooled sufficiently to retain liquid water on its surface, forming oceans.

Early Earth Volcanic Outgassing

The release of gases—such as water vapour, carbon dioxide (or nitrogen), and small amounts of methane and ammonia—from early Earth volcanoes, forming the early atmosphere and oceans.

Water Polarity

The property of a water molecule having an uneven distribution of electrons between the oxygen atom and hydrogen atoms, giving oxygen a stronger pull on electrons.

Polar Covalent Bond (in Water)

The chemical bond within a water molecule between oxygen and hydrogen, characterized by unequal electron sharing.

Hydrogen Bond (Water Attraction)

An attractive force between distinct water molecules resulting from the partial positive charge on a hydrogen atom and the partial negative charge on an oxygen atom of an adjacent molecule.

Protocells

Droplets enclosed by membranes that maintain an internal chemistry different from that of their surroundings, representing a stage in early cell formation.

Liposome vs. Micelle

Lipid self-assembly structures: a liposome consists of a lipid bilayer surrounding an aqueous center, while a micelle is a single-layered lipid sphere.

Four Stages of Early Cell Origin

1. Abiotic synthesis of small organic molecules; 2. Joining of small molecules into macromolecules; 3. Origin of self-replicating molecules (enabling inheritance); 4. Packaging of molecules into protocells.

Oparin-Haldane Hypothesis

The proposal by A. I. Oparin and J. B. S. Haldane that Earth's early atmosphere was a reducing environment conducive to the synthesis of organic molecules.

Miller-Urey Experiment Apparatus

A laboratory apparatus designed by Stanley Miller and Harold Urey to test abiotic synthesis in a simulated reducing atmosphere containing $\text{CH}_4$, $\text{H}_2$, $\text{NH}_3$, and $\text{H}_2\text{O}$, powered by electric sparks.

Primitive Soup

The starting solution of water and inorganic compounds in prebiotic synthesis experiments, which upon energy application yields organic molecules like amino acids, hydrocarbons, and nitrogenous bases.