Human Anatomy & Physiology Chapter 2: Basic Chemistry & Biochemistry

Comprehensive vocabulary flashcards covering basic chemistry, atomic structure, bonding, chemical reactions, inorganic compounds, and organic biochemistry from Chapter 2.

Matter

Anything that has mass and occupies space.

Kinetic Energy

Energy in action.

Potential Energy

Stored or inactive energy that has the capacity to do work.

Chemical Energy

Form of energy stored in the chemical bonds of substances.

Atomic Symbol

A one- or two-letter chemical shorthand for an element (e.g., $O$ for oxygen, $Na$ for natrium, $K$ for kalium).

Proton

A subatomic particle located in the nucleus carrying a positive charge ($+1$) and weighing an arbitrary $1\,\text{amu}$.

Neutron

A subatomic particle located in the nucleus carrying no electrical charge ($0$) and weighing $1\,\text{amu}$.

Electron

A subatomic particle orbiting the nucleus carrying a negative charge ($-1$) with virtually no weight ($0\,\text{amu}$).

Planetary Model

A simplified, outdated atomic model depicting electrons in fixed circular orbits around the nucleus.

Orbital Model

The modern atomic model depicting probable regions (orbitals) where an electron is most likely located, creating an electron cloud.

Atomic Number

The number of protons in an atom's nucleus, written as a subscript to the left of the atomic symbol.

Mass Number

The total number of protons and neutrons in an atom's nucleus, written as a superscript to the left of the atomic symbol.

Isotopes

Structural variations of the same element whose atoms contain the same number of protons but differ in the number of neutrons.

Radioisotopes

Isotopes that decay spontaneously to more stable forms, losing subatomic particles and releasing radioactivity.

Compound

A specific molecule containing two or more different kinds of atoms bonded together (e.g., $C_6H_{12}O_6$).

Solution

A homogeneous mixture in which solute particles are evenly distributed throughout a solvent.

Solvent

The dissolving medium in a solution present in the greatest amount, usually a liquid such as water.

Solute

The substance dissolved in a solvent, present in smaller amounts (e.g., glucose in blood plasma).

Molarity ($M$)

A unit of concentration defined as the number of moles of solute per liter of solvent.

Avogadro's Number

The fixed number of molecules contained in one mole of any substance, equal to $6.02 \times 10^{23}$.

Colloid

Also called an emulsion; a heterogeneous mixture containing large solute particles that scatter light but do not settle out, often undergoing sol-gel transformations.

Suspension

A heterogeneous mixture containing large, visible solutes that settle out of solution over time (e.g., blood).

Valence Shell

An atom's outermost electron shell containing the electrons with the most potential energy, which are involved in chemical bonding.

Octet Rule

The driving principle in chemical bonding stating that atoms gain, lose, or share electrons to achieve 8 valence electrons (or 2 for shell 1).

Anion

An ion carrying a net negative charge, formed when an atom gains one or more electrons.

Cation

An ion carrying a net positive charge, formed when an atom loses one or more electrons.

Ionic Bond

A chemical bond formed by the complete transfer of valence shell electrons from one atom to another, creating oppositely charged ions that attract.

Covalent Bond

A chemical bond formed when two atoms share two or more valence shell electrons.

Nonpolar Covalent Bond

A covalent bond formed by the equal sharing of electrons between atoms, resulting in an electrically balanced molecule (e.g., $CO_2$).

Polar Covalent Bond

A covalent bond formed by unequal sharing of electrons between atoms with differing electronegativities, creating partial charges (e.g., $H_2O$).

Hydrogen Bond

A weak attraction between an electropositive hydrogen atom of one dipole and an electronegative atom of another dipole.

Synthesis Reaction

An anabolic chemical reaction in which smaller atoms or molecules combine to form a larger, more complex molecule.

Decomposition Reaction

A catabolic chemical reaction in which bonds in a larger molecule are broken to form smaller, less complex molecules.

Exchange Reaction

Also called a displacement reaction; a chemical reaction involving both synthesis and decomposition, where bonds are both made and broken.

Redox Reaction

Short for reduction-oxidation reaction; a chemical reaction where one atom gains electrons (is reduced) and another loses electrons (is oxidized).

Exergonic Reaction

A chemical reaction that results in a net release of energy, yielding products with less potential energy than the reactants.

Endergonic Reaction

A chemical reaction that absorbs energy, yielding products with more potential energy than the reactants.

Electrolytes

Chemical substances (salts, acids, bases) that ionize and dissociate in water, producing ions capable of conducting electrical currents.

Acid

A substance that acts as a proton donor by releasing hydrogen ions ($H^+$) in solution.

Base

A substance that acts as a proton acceptor by binding free hydrogen ions ($H^+$) in solution (often releasing hydroxyl ions, $OH^-$).

pH Scale

A logarithmic measurement scale of hydrogen ion concentration $[H^+]$ in solution, ranging from 0 to 14.

Buffer

A chemical system that resists abrupt and large swings in $pH$ by binding hydrogen ions when $pH$ drops and releasing them when $pH$ rises.

Dehydration Synthesis

A reaction that covalently joins monomers into polymers by removing an $-OH$ group from one monomer and an $-H$ from another, releasing $H_2O$.

Hydrolysis

A catabolic reaction that breaks polymer bonds into monomers by adding a water molecule ($H_2O$).

Monosaccharide

A simple single sugar monomer containing 3 to 7 carbon atoms, with the general formula $(CH_2O)_n$.

Disaccharide

A double sugar formed by the dehydration synthesis of two monosaccharides (e.g., sucrose, lactose, maltose).

Polysaccharide

A long polymer chain of linked monosaccharides (e.g., starch in plants, glycogen in animals).

Triglyceride

A lipid composed of three fatty acid chains bonded to a glycerol molecule; functions in energy storage, insulation, and protection.

Saturated Fatty Acid

A fatty acid chain with only single covalent bonds between carbon atoms, saturated with hydrogen atoms and solid at room temperature.

Unsaturated Fatty Acid

A fatty acid chain containing one or more double bonds between carbons, creating kinks that prevent tight packing and keeping it liquid at room temperature.

Phospholipid

A modified triglyceride containing glycerol, two fatty acids, and a phosphorus group, featuring a polar hydrophilic head and nonpolar hydrophobic tails.

Steroid

A lipid molecule composed of four interlocking hydrocarbon rings (e.g., cholesterol).

Eicosanoid

A lipid derivative of 20-carbon arachidonic acid found in cell membranes, including prostaglandins that mediate inflammation and blood clotting.

Peptide Bond

The covalent bond formed between the amine group of one amino acid and the acid group of another via dehydration synthesis.

Primary Structure

The linear sequence of amino acids forming a polypeptide chain.

Secondary Structure

The coiling of a primary polypeptide chain into an $\alpha$-helix or folding into a $\beta$-pleated sheet, stabilized by hydrogen bonds.

Tertiary Structure

The overall 3-D globular shape formed when secondary protein structures fold together via intramolecular bonds.

Quaternary Structure

The structural level resulting from the combination of two or more polypeptide chains, each with its own tertiary structure.

Fibrous Proteins

Structural, strandlike, water-insoluble, stable proteins providing mechanical support and tensile strength (e.g., collagen, keratin).

Globular Proteins

Functional, compact, spherical, water-soluble proteins containing active sites (e.g., enzymes, antibodies, hormones).

Denaturation

The unfolding of globular proteins causing loss of their functional 3-D shape and active sites, typically induced by changes in $pH$ or temperature.

Holoenzyme

A complete, functional enzyme consisting of an apoenzyme (protein component) and a cofactor (metal ion) or coenzyme (organic molecule/vitamin).

Activation Energy

The initial amount of energy required to initiate a chemical reaction, which is lowered by biological enzymes.

Nucleotide

The monomer of nucleic acids, consisting of a nitrogen-containing base, a pentose sugar, and a phosphate group.

DNA (Deoxyribonucleic Acid)

A double-stranded helical nucleic acid containing deoxyribose sugar and bases A, T, C, and G, serving as the cell's genetic blueprint.

RNA (Ribonucleic Acid)

A single-stranded linear nucleic acid containing ribose sugar and bases A, U, C, and G, which carries out protein synthesis orders outside the nucleus.

ATP (Adenosine Triphosphate)

The primary cellular energy transfer molecule, composed of an adenine RNA nucleotide with three phosphate groups connected by high-energy bonds.