The Chemistry of Life

Vocabulary flashcards covering key concepts from the lecture notes on The Chemistry of Life.

Biochemistry

The study of the molecules that compose living organisms and the molecules unique to life (carbohydrates, fats, proteins, nucleic acids); essential for understanding physiology and treatment choices.

Element

The simplest form of matter with a unique set of properties; hydrogen and oxygen are elements, water is not.

Atom

The basic unit of matter made of protons, neutrons in the nucleus and electrons in surrounding shells.

Atomic number

The number of protons in an atom’s nucleus; identifies the element.

Proton

Positively charged particle in the nucleus (mass ~1 amu).

Neutron

Electrically neutral particle in the nucleus (mass ~1 amu).

Electron

Negatively charged particle surrounding the nucleus; very small mass; valence electrons determine bonding.

Nucleus

Center of the atom containing protons and neutrons.

Valence electrons

Electrons in the outermost shell that determine chemical bonding properties.

Isotope

Variants of an element with the same number of protons but different numbers of neutrons and atomic mass.

Radioactivity

Emission of radiation by unstable isotopes as they decay to more stable forms.

Radioisotope

An unstable isotope that emits radiation.

Half-life

Time required for 50% of a radioactive substance to decay (physical half-life) or to disappear from the body (biological half-life).

Ion

A charged particle formed when electrons are gained or lost; can be a single atom, a group, or a molecule.

Anion

Negatively charged ion (gains electrons).

Cation

Positively charged ion (loses electrons).

Ionization

Transfer of electrons from one atom to another.

Electrolyte

Substance that ionizes in water to form a solution that conducts electricity.

Free radical

Unstable, highly reactive atom or molecule with an unusual number of electrons.

Major elements

The six elements that make up about 98.5% of body weight: oxygen, carbon, hydrogen, nitrogen, calcium, phosphorus.

Trace elements

Elements found in very small amounts but vital; some can be toxic in excess (e.g., lead, mercury).

Minerals

Inorganic elements taken from soil by plants and passed to humans; contribute to structure, enzymes, and body functions.

Water

H2O; polar molecule with hydrogen bonding; universal solvent essential for solvency, adhesion, cohesion, and thermoregulation.

Hydrogen bond

Weak attraction between a slightly positive hydrogen and a slightly negative atom (usually O or N); crucial in water and macromolecules.

Ionic bond

Attraction between a cation and an anion; often easily disrupted by water.

Covalent bond

Atoms share one or more electron pairs; can be single or double.

Polar covalent bond

Covalent bond with unequal sharing of electrons, creating partial charges.

Nonpolar covalent bond

Covalent bond where electrons are shared equally.

Hydrogen bond (in context)

Weak attraction between a hydrogen atom and a highly electronegative atom (O or N); important in structure of macromolecules.

Van der Waals forces

Weak, brief attractions due to transient dipoles; important in protein folding and molecular interactions.

Solvent

Substance (often water) that dissolves solutes to form a solution.

Solute

Substance dissolved in a solvent.

Solution

Uniform mixture where solute is dispersed in solvent at the molecular level.

Colloid

Aqueous mixture with particles too large to pass membranes but too small to settle; often gels or suspensions of proteins, etc.

Suspension

Mixture with large particles that tend to settle out.

Emulsion

Suspension of one liquid in another (e.g., oil in water).

Hydrophilic

Substances that dissolve in water (polar or charged).

Hydrophobic

Substances that do not dissolve in water (nonpolar).

Adhesion

Tendency of water to cling to surfaces and membranes.

Cohesion

Tendency of like molecules to stick together due to hydrogen bonding; contributes to surface tension.

Surface tension

Tendency of liquid surface to resist external force due to cohesive forces.

Solvency

Ability of a solvent to dissolve substances (solvents like water).

pH scale

Scale measuring acidity/basicity based on H+ concentration; 7 neutral;

Acid

Proton donor; substances that release H+ in water.

Base

Proton acceptor; substances that accept H+ in water.

Buffer

Chemical solution that resists changes in pH by neutralizing small amounts of acid or base.

ATP

Adenosine triphosphate; primary energy-transfer molecule; energy stored in phosphate bonds and released by hydrolysis to ADP + Pi.

ADP

Adenosine diphosphate; product of ATP hydrolysis with inorganic phosphate.

Nucleotides

Building blocks of nucleic acids consisting of a nitrogenous base, a sugar, and one or more phosphate groups.

Nitrogenous base

Ring-containing base (adenine, thymine, cytosine, guanine, uracil) in nucleotides.

Ribose

Sugar component of RNA nucleotides.

Phosphate group

Phosphorylated unit that links nucleotides; energy-containing in ATP.

Nucleic acids

Polymers of nucleotides (DNA and RNA) that store and express genetic information.

DNA

Deoxyribonucleic acid; stores genetic information.

RNA

Ribonucleic acid; carries out genetic instructions for protein synthesis.

Functional groups

Groups of atoms with characteristic properties (examples: hydroxyl, methyl, carboxyl, amino, phosphate).

Activation energy

Minimum energy required to start a chemical reaction; enzymes lower this barrier.

Enzyme

Biological catalyst, mostly proteins (some RNA); speeds reactions at body temperature.

Active site

Region of an enzyme where the substrate binds.

Substrate

Substance acted upon by an enzyme.

Enzyme–substrate complex

Temporary complex formed when substrate binds to the enzyme’s active site.

Lock and key

Concept of enzyme specificity: specific substrate fits a specific active site.

Metabolism

All chemical reactions in the body; includes catabolism and anabolism.

Catabolism

Energy-releasing breakdown of molecules; produces smaller molecules and heat.

Anabolism

Energy-storing synthesis of larger molecules from smaller ones.

Oxidation

Loss of electrons; often releases energy; paired with reduction.

Reduction

Gain of electrons; coupled with oxidation in redox reactions.