Chapter 02: The Chemistry of Life

Vocabulary flashcards covering atomic structure, chemical bonding, reactions, and organic/inorganic compounds based on Human Anatomy and Physiology lecture notes.

Matter

Anything that has mass and occupies space.

Chemistry

Study of matter and its interactions.

Atom

Smallest unit of matter that still retains its original properties.

Element

Substance composed of one or more identical atoms that cannot be broken down into simpler substances by chemical means.

Protons

Positively charged particles that reside in the central core, or Atomic Nucleus, of the atom.

Neutrons

Uncharged particles that are slightly larger than protons and also reside in the atomic nucleus.

Electrons

Negatively charged tiny particles that surround the atomic nucleus.

Electron Shells

Regions surrounding the atomic nucleus where electrons are found; the 1st shell holds $2$ electrons, the 2nd holds $8$, and the 3rd holds $18$ but is satisfied with $8$.

Atomic Number

The number of protons in the atomic nucleus, which defines the element.

Periodic Table of Elements

A list of elements in order of increasing atomic number showing properties that repeat in a regular way.

Major Elements of the Human Body

Four elements making up $96 \%$ of body mass: Oxygen ($65 \%$), Carbon ($18 \%$), Hydrogen ($10 \%$), and Nitrogen ($3 \%$).

Mineral Elements

Seven elements making up less than $4 \%$ of body mass: Sodium (Na), Potassium (K), Calcium (Ca), Chlorine (Cl), Magnesium (Mg), Phosphorus (P), and Sulfur (S).

Trace Elements

Thirteen elements including Iron (Fe), Copper (Cu), Iodine (I), and Zinc (Zn) found in very small amounts in the body.

Mass Number

The sum of all protons and neutrons in the atomic nucleus.

Isotope

Atom with the same number of protons (atomic number) but different number of neutrons (mass number).

Radioisotopes

Unstable isotopes that release energy as radiation and form the basis for nuclear medicine.

Mixture

Atoms of $2$ or more elements physically intermixed without changing their chemical nature; can be physically separated.

Molecule

Two or more atoms combined by chemical means with different properties from the original atoms; can only be separated chemically.

Suspensions

Mixture of a liquid and a solid where large solid particles are visible and will settle out.

Colloids

Mixture of a liquid and a solid where small solid particles are not visible and remain dispersed, appearing opaque.

Solutions

Mixture where a solute dissolves in a solvent (usually water), appearing translucent.

Chemical Bonds

An energy relationship or attractive force between atoms.

Compound

Forms when $2$ or more atoms of different elements are chemically bonded.

Valence Electrons

Electrons in the outermost shell (Valence Shell) that interact to form chemical bonds.

Octet Rule

Principle stating that an atom is most stable with $8$ electrons in its valence shell.

Duet Rule

Stability rule for atoms with $5$ or fewer electrons, achieved with $2$ electrons in the first shell.

Ionic Bond

Bond formed when electrons are transferred between a metal atom and a nonmetal atom.

Ion

A charged atom that has gained or lost an electron; includes Cations (positive) and Anions (negative).

Covalent Bond

Sharing of electrons between two or more nonmetal atoms; the strongest type of chemical bond.

Nonpolar Covalent Bond

Bond where electrons are shared equally between atoms of the same element or between carbon and hydrogen.

Polar Covalent Bond

Bond where electrons are shared unequally due to differences in electronegativity, creating dipoles.

Hydrogen Bonds

Weak attractions between partially positive and partially negative atoms in polar covalent molecules.

Surface Tension

Result of polar water molecules clustering and forming hydrogen bonds where air and water meet.

Chemical Reaction

Occurs whenever chemical bonds are formed, broken, rearranged, or electrons are transferred.

Energy

The capacity to do work; can be Potential (stored) or Kinetic (in motion).

Chemical Energy

Energy stored in chemical bonds that drives cellular processes.

Endergonic Reactions

Reactions that require an investment of energy; products contain more energy than reactants.

Exergonic Reactions

Reactions where excess energy stored in reactants is released.

Catabolic Reactions

Generally exergonic reactions where larger substances are broken down into smaller ones.

Anabolic Reactions

Generally endergonic reactions that form new chemical bonds to build new compounds.

Oxidation-Reduction (Redox) Reactions

Exergonic reactions involving electron exchange; the reactant losing electrons is Oxidized, and the one gaining electrons is Reduced.

Activation Energy

The energy required to allow strong collisions of reactant electrons so a reaction can proceed.

Enzymes

Biological catalysts, mostly proteins, that increase reaction rates by lowering activation energy without being permanently altered.

Tay-Sachs Disease

Deficiency of hexosaminidase leading to ganglioside accumulation around brain cells and death usually by age $3$.

Phenylketonuria

Deficiency of phenylalanine hydroxylase, preventing conversion of phenylalanine to tyrosine, causing seizures and mental retardation.

Inorganic Compounds

Compounds that do not contain carbon bonded to hydrogen, such as water, acids, bases, and salts.

Hydrophilic

Property of 'water loving' solutes with partially charged ends that dissolve in water.

Hydrophobic

Property of 'water hating' solutes, such as uncharged nonpolar covalent molecules, that do not dissolve in water.

Acids

Hydrogen ion ($H^+$) or proton donors that increase the number of hydrogen ions in water.

Bases (Alkali)

Hydrogen ion ($H^+$) or proton acceptors that decrease the number of hydrogen ions in water.

pH Scale

A representation of hydrogen ion concentration; neutral is $7$, acidic is below $7$, and basic is above $7$.

Buffers

Chemical systems consisting of a weak acid and its anion that resist changes in pH.

Acidosis

Condition occurring if blood pH falls below $7.35$.

Alkalosis

Condition occurring if blood pH rises above $7.45$.

Electrolytes

Cations and anions resulting from salts dissolved in water that conduct an electric current.

Monomers

Single subunits that are combined to build larger structures called polymers.

Dehydration Synthesis

Reaction that links $2$ monomers together using a molecule of water.

Hydrolysis Reaction

Reaction that splits a polymer by adding a molecule of water.

Carbohydrates

Polar, hydrophilic compounds made of C, H, and O in a $1C : 2H : 1O$ ratio; function primarily as fuel.

Glucose

A monosaccharide that serves as the primary source of fuel for the body.

Glycogen

The main storage polysaccharide in animals, stored in the liver and skeletal muscles.

Lipids

Nonpolar, hydrophobic compounds including fats and oils; function as fuel, membrane components, and hormones.

Phospholipids

Amphiphilic molecules with a polar phosphate head and nonpolar fatty acid tails; main structural component of cell membranes.

Steroids

Lipids with a $4$-ring hydrocarbon nucleus; includes cholesterol, bile acids, estrogen, and testosterone.

Proteins

Molecules made of amino acids that perform structural, enzymatic, defensive, and communicative roles; make up $20 \%$ of body mass.

Primary Structure

The specific amino acid sequence of a polypeptide held together by peptide bonds.

Secondary Structure

Folding of a polypeptide into an Alpha Helix or Beta-Pleated Sheet, stabilized by hydrogen bonds.

Protein Denaturation

Loss of protein shape and function due to heat, pH changes, or chemicals disrupting hydrogen bonds and ionic interactions.

Nucleotides

Monomers of nucleic acids composed of a nitrogenous base, a five-carbon sugar, and a phosphate group.

Adenosine Triphosphate (ATP)

Nucleotide that serves as the main source of chemical energy for driving cellular processes.

DNA (Deoxyribonucleic Acid)

Double-helix polymer containing deoxyribose sugar and bases A, G, C, T; specifies the amino acid sequence of proteins via genes.

RNA (Ribonucleic Acid)

Single-strand nucleotide polymer containing ribose sugar and Uracil instead of Thymine; carries assembly instructions for proteins to the cytosol.