General Chemistry, Biomolecules, and the Origin of Life Flashcards

Vocabulary flashcards covering foundational chemistry principles, molecular forces, the four major classes of biomolecules, polymer synthesis/breakdown, and primordial prebiotic chemistry.

Atom

The smallest unit of matter that retains chemical properties, composed of protons, neutrons, and electrons.

Cell

The smallest unit of life, defined as a membrane-bound structure capable of processing information, acquiring energy, evolving, and reproducing.

Element

A pure substance made up entirely of one specific type of atom.

Proton

A positively charged subatomic particle located in the nucleus that contributes to atomic mass and determines the identity of an element.

Neutron

A neutral subatomic particle located in the nucleus that contributes to atomic mass and determines the isotope of an element.

Electron

A negatively charged subatomic particle found in the electron cloud surrounding the nucleus that has negligible mass and determines chemical behavior.

Valence Electrons

Electrons located in the outermost shell of an atom that participate in chemical bonding.

Electronegativity

An atom's measure of attraction or pull for electrons within a chemical bond.

Ionic Bond

A bond formed when an atom completely transfers electrons to another atom due to a large electronegativity difference ($1.8$ to $3.3$), forming positively charged cations and negatively charged anions.

Covalent Bond

A chemical bond formed when two atoms share electrons to complete their valence shells, typically occurring between atoms with an electronegativity difference of less than $1.8$.

Polar Covalent Bond

A covalent bond characterized by unequal electron sharing between atoms with an electronegativity difference of $0.5$ to $1.7$, creating partial positive (̤̤\delta+) and partial negative ($\delta-$) charges.

Nonpolar Covalent Bond

A covalent bond characterized by equal sharing of electrons between atoms with an electronegativity difference of $0$ to $0.4$.

Intramolecular Bond

A chemical bond, such as a covalent or ionic bond, that holds atoms together within a single molecule.

Intermolecular Bond

A weak interaction that occurs between separate, distinct molecules due to attractive forces between partial or full charges.

Hydrogen Bond

An intermolecular force formed when a partially positive hydrogen atom on one polar molecule is attracted to a partially negative oxygen or nitrogen atom on another polar molecule.

Hydrophilic

A property of polar or ionic molecules that allows them to interact with and dissolve in water.

Hydrophobic

A property of nonpolar molecules that prevents them from dissolving in or forming hydrogen bonds with water.

Monomer

A small single subunit that serves as a building block for larger biological molecules.

Dimer

A structure consisting of two monomers joined together by a covalent bond.

Polymer

A large molecule composed of many repeating monomer subunits covalently bound together.

Dehydration Reaction (Polymerization)

A reaction that covalently joins monomers together to form a polymer, producing a water molecule ($\text{H}_2\text{O}$) and requiring a net input of energy.

Hydrolysis Reaction (Depolymerization)

A reaction that breaks covalent bonds in a polymer to split it into monomers, requiring the addition of a water molecule ($\text{H}_2\text{O}$) and releasing energy.

Monosaccharide

The monomer of carbohydrates, with the general formula $\text{C}_n\text{H}_{2n}\text{O}_n$ or $(\text{CH}_2\text{O})_n$, utilized for energy storage and structural support.

Disaccharide

A carbohydrate dimer consisting of two monosaccharides linked by a covalent bond via dehydration (e.g., sucrose, lactose, maltose).

Polysaccharide

A complex carbohydrate polymer made of long chains of monosaccharides (e.g., starch, glycogen, cellulose).

Lipid

A class of biomolecules defined by its insolubility in water (nonpolar and hydrophobic), composed primarily of carbon and hydrogen with minimal oxygen.

Triglyceride

A lipid composed of a glycerol backbone covalently attached to three fatty acid chains via dehydration reactions.

Phospholipid

An amphipathic lipid consisting of a glycerol backbone, two hydrophobic fatty acid chains, and a hydrophilic modified phosphate group.

Amphipathic

Refers to a molecule that possesses both hydrophilic (polar/charged) and hydrophobic (nonpolar) regions.

Amino Acid

The monomer of proteins, consisting of a central carbon atom bound to a hydrogen, an amino group, a carboxyl group, and a variable R group.

Peptide Bond

The covalent bond joining amino acids together during a dehydration reaction.

Polypeptide

A polymer of amino acids joined by peptide bonds with a characteristic backbone of $\text{N-C-C}$, which folds into a functional protein.

Oparin-Haldane Hypothesis

The hypothesis that organic biomolecule monomers formed spontaneously $3.7$ to $4\,\text{billion}$ years ago from atmospheric gases in an oxygen-free environment powered by lightning and UV radiation.

Nucleotide

The monomer of nucleic acids, composed of a 5-carbon pentose sugar, up to 3 phosphate groups attached at the 5' carbon, and a nitrogenous base attached at the 1' carbon.

Purines

Two-ringed nitrogenous bases found in nucleotides, consisting of Adenine ($\text{A}$) and Guanine ($\text{G}$).

Pyrimidines

Single-ringed nitrogenous bases found in nucleotides, consisting of Cytosine ($\text{C}$), Uracil ($\text{U}$), and Thymine ($\text{T}$).