BIOSC 150: Evolution, Chemistry of Life, and Biomolecules

A set of vocabulary-style flashcards covering key concepts from evolution, atomic structure, chemical bonds, water properties, acids/bases, nucleic acids, DNA/RNA, and proteins. Each card presents a term and a concise definition to aid quick study.

Endosymbiosis

A theory that eukaryotic organelles (like mitochondria and chloroplasts) originated when one cell engulfed another cell, resulting in a symbiotic, double-membrane relationship.

Photosynthesis

Process by which organisms use light energy to convert carbon dioxide and water into glucose and oxygen.

Mitochondria

Organelles thought to have originated from engulfed aerobic bacteria; the cell’s powerhouses that generate most of the ATP.

Atom

The basic unit of matter; the smallest unit of an element capable of retaining its properties.

Dalton

Unit of atomic mass used to express atomic and molecular weights.

Isotope

Atoms of the same element with different numbers of neutrons and thus different atomic masses.

Radioisotope

A radioactive isotope that emits radiation as it decays.

Electron

Negatively charged subatomic particle orbiting the nucleus; has negligible mass.

Proton

Positively charged subatomic particle located in the nucleus.

Neutron

Electrically neutral subatomic particle located in the nucleus.

Covalent bond

Chemical bond formed by sharing electrons between atoms.

Polar covalent bond

Covalent bond where electrons are shared unequally due to differences in electronegativity.

Nonpolar covalent bond

Covalent bond where electrons are shared fairly evenly between atoms.

Ionic bond

Bond formed by electrical attraction between oppositely charged ions created by electron transfer.

Electronegativity

Tendency of an atom to attract electrons in a chemical bond.

Hydrogen bond

Weak bond between a hydrogen atom and a highly electronegative atom (typically O or N) important in DNA and protein folding.

Van der Waals forces

Weak, transient intermolecular attractions due to momentary dipoles between molecules.

Hydrophobic interactions

Clustering of nonpolar molecules in aqueous environments to minimize contact with water.

Water

Polar solvent essential for life; high heat capacity, cohesive and adhesive properties, and solvent abilities.

Polar molecule

Molecule with partial positive and negative charges due to uneven electron distribution.

Specific heat

Amount of heat required to raise the temperature of a substance; water has a high specific heat.

Heat of vaporization

Energy required to convert a liquid to a gas.

Ice density

Ice is less dense than liquid water and floats, insulating bodies of water.

pH

Negative logarithm of the hydrogen ion concentration; measure of acidity or basicity.

Acid

Substance that increases H+ concentration in solution (donates protons).

Base

Substance that reduces H+ concentration or accepts protons.

Nucleic acid

Macromolecule that stores and transmits genetic information (DNA and RNA).

DNA

Deoxyribonucleic acid; stores genetic information; typically double-stranded.

RNA

Ribonucleic acid; involved in transcription and translation; often single-stranded.

Nucleotide

Building block of nucleic acids; consists of a sugar, phosphate, and a nitrogenous base.

Purine

Double-ring nitrogenous base (adenine and guanine).

Pyrimidine

Single-ring nitrogenous base (cytosine, thymine, uracil).

Adenine

Purine base that pairs with thymine in DNA and with uracil in RNA.

Guanine

Purine base that pairs with cytosine.

Cytosine

Pyrimidine base that pairs with guanine.

Thymine

Pyrimidine base that pairs with adenine in DNA.

Uracil

Pyrimidine base that pairs with adenine in RNA (replaces thymine in RNA).

Base pairing

Hydrogen-bonded pairing of complementary bases (A-T in DNA; A-U in RNA; C-G in both).

Antiparallel

Two DNA strands run in opposite directions (5' to 3' and 3' to 5').

Double helix

The two complementary DNA strands coiled into a helical shape.

Amino acid

Monomer of proteins; contains an amino group, a carboxyl group, a hydrogen, and an R group attached to a central carbon.

Peptide bond

Covalent bond linking amino acids in a polypeptide chain.

Amino group

NH2 group found on amino acids.

Carboxyl group

COOH group found on amino acids; acidic in nature.

R group (side chain)

Variable side chain that determines the properties and identity of each amino acid.

Zwitterion

A molecule that carries both positive and negative charges at physiological pH, as amino acids do.

Disulfide bond

Covalent bond between sulfur atoms in cysteine residues that stabilizes protein structure.

Denaturation

Loss of a protein’s native structure (and function) due to heat, pH, or other factors.

Heme

Iron-containing component of hemoglobin that binds oxygen.

Hemoglobin

Oxygen-transport protein in blood that contains heme groups.

Oxygen binding

Process of oxygen attaching to the iron in heme within hemoglobin.

Primary structure

Linear sequence of amino acids in a protein.

Secondary structure

Localized folding patterns (alpha helices, beta sheets) stabilized mainly by hydrogen bonds.

Tertiary structure

Overall three-dimensional shape of a single polypeptide, stabilized by various interactions.

Quaternary structure

Arrangement of multiple polypeptide subunits into a functional protein.

Polysaccharide

Carbohydrate polymer made of sugar monomers; provides energy and structural support.

Carbohydrates

Macromolecules composed of sugar monomers; flagging roles in energy storage and structure.

Lipids

Nonpolar biomolecules (fats, oils, phospholipids) that store energy and form cellular membranes.