Lecture 3: Origin of Life and Chemical Foundations

Vocabulary flashcards covering origin-of-life concepts, biopolymers, chemical bonding, electronegativity, intermolecular forces, and quantitative biochemistry measurements.

Ribozyme

An RNA molecule that can catalyze chemical reactions, including protein synthesis.

LUCA (Last Universal Common Ancestor)

The common ancestor to all life on Earth, positioned at the base of the universal tree of life.

Covalent Bond

A bond in which two atoms share electrons, which are distributed between the bonded atoms.

Ionic Bond

A bond in which electrons are transferred from one atom to another, resulting in the formation of positively and negatively charged ions that attract each other.

Electronegativity

The affinity of a bonded atom for electrons, describing how strongly an atom pulls electrons toward itself.

Pauling Scale

An arbitrary numerical scale for measuring electronegativity, named after Linus Pauling.

Electric Dipole Moment

The separation of positive ($\delta^+$) and negative ($\delta^-$) charges within a molecule due to unequal electron distribution.

Hydrophobic

Meaning "water-fearing"; describes nonpolar molecules that cannot interact favorably with water and tend to aggregate away from it.

Hydrophilic

Meaning "water-loving"; describes polar molecules that can interact favorably with water through dipole interactions.

Intermolecular Forces

Secondary forces representing attractions and repulsions between separate molecules, which are generally weaker than covalent or ionic bonds.

Hydrogen Bond

A strong type of dipole-dipole interaction that occurs when hydrogen is covalently bonded to highly electronegative atoms like oxygen, fluorine, or nitrogen.

Van der Waals Forces

Weak dispersion forces between nonpolar molecules caused by temporary or induced dipoles in electron clouds.

Angstrom

A unit of spatial measurement equal to $10^{-10}\,\text{m}$ or $0.1\,\text{nm}$.

Henderson-Hasselbalch Equation

A foundational mathematical equation used to calculate pH, pK, and buffer properties in biological systems.

pH

A fundamental biochemical measurement representing the concentration of hydrogen ions in a solution.

pK

A value related to the acid dissociation constant $K_a$, defined by the mathematical expression $pK = \log(K_a)$.

Isoelectric Point

The specific pH at which a molecule carries no net electrical charge.

DNA (Deoxyribonucleic Acid)

An extremely stable, double-stranded biopolymer that primarily functions to store genetic information in cells.

RNA (Ribonucleic Acid)

A structurally complex, typically single-stranded biopolymer capable of both genetic information storage and chemical catalysis.