The Chemical Level of Organization (Chapter 3)

Vocabulary flashcards covering key terms and definitions from the chemical level of organization in anatomy and physiology.

Matter

Anything that occupies space and has mass.

Mass

The amount of matter contained in an object (mass is not the same as weight).

Weight

The force of gravity on matter; can vary with location.

Element

A pure substance made of a single type of atom.

Atom

The smallest unit of an element that retains its properties.

Molecule

Two or more atoms chemically bound together.

Compound

Two or more elements joined by chemical bonds.

Subatomic particle

Particles that make up atoms (protons, neutrons, electrons).

Proton

Positively charged subatomic particle in the nucleus.

Neutron

Neutral subatomic particle in the nucleus.

Electron

Negatively charged subatomic particle surrounding the nucleus.

Atomic number

Number of protons in an atom.

Atomic weight

Approximate total mass of an atom (protons + neutrons + small contribution from electrons).

Mass number

Sum of protons and neutrons in an atom.

Isotopes

Different forms of an element with varying numbers of neutrons.

Protium

Hydrogen-1: 1 proton, 0 neutrons.

Deuterium

Hydrogen-2: 1 proton, 1 neutron.

Tritium

Hydrogen-3: 1 proton, 2 neutrons; radioactive.

Ion

An atom with an electrical charge (positive or negative).

Cation

Positively charged ion.

Anion

Negatively charged ion.

Electron shells

Regions around the nucleus that hold electrons; typically 2–8 per shell.

Valence shell

Outermost electron shell; atoms react to fill it.

Ionic bonds

Electrical attraction between oppositely charged ions.

Covalent bonds

Atoms share electrons to form bonds.

Polar covalent bonds

Unequal sharing of electrons between atoms.

Nonpolar covalent bonds

Equal sharing of electrons between atoms.

Hydrogen bonds

Attractions between molecules, common in water.

Water

Universal solvent; polar; supports lubrication, temperature regulation, and chemical reactions.

Solution

A mixture where a solute is dissolved in a solvent.

Solvent

Substance that dissolves another substance.

Solute

Substance dissolved in the solvent.

Colloid

Mixture with larger particles that may appear cloudy or opaque.

Suspension

Mixture where heavier particles settle out over time.

Dehydration synthesis

Building larger molecules by removing water.

Hydrolysis

Breaking bonds by adding water.

pH

Scale (0–14) measuring acidity/alkalinity; 7 is neutral.

Buffers

Substances that resist rapid changes in pH.

Acids

Substances that release H+ ions in solution.

Bases

Substances that release OH− or bind H+ in solution.

Inorganic

Compounds that do not contain both carbon and hydrogen.

Organic

Compounds that contain both carbon and hydrogen.

Carbohydrates

Macromolecules that provide energy; C, H, O; typical 2:1 H:O ratio.

Monosaccharides

Simple sugars (e.g., glucose, fructose, galactose, ribose, deoxyribose).

Disaccharides

Two monosaccharides (e.g., sucrose, lactose, maltose).

Polysaccharides

Many monosaccharides (e.g., starches, glycogen, cellulose).

Glucose

Major monosaccharide used for cellular energy.

Fructose

Monosaccharide found in fruits; isomer of glucose.

Galactose

Monosaccharide isomer of glucose.

Ribose

Five-carbon sugar in RNA.

Deoxyribose

Five-carbon sugar in DNA.

Starches

Plant storage polysaccharide.

Glycogen

Animal storage polysaccharide.

Cellulose

Plant cell wall polysaccharide.

Lipids

Hydrocarbon-rich, nonpolar molecules; energy storage and insulation.

Triglycerides

Most common dietary lipid; glycerol with three fatty acids.

Phospholipids

Lipids with a phosphorus-containing head; form cellular membranes.

Cholesterol

Sterol; membrane stability; precursor to hormones.

Prostaglandins

Lipid mediators involved in inflammation.

Fatty acids

Saturated vs. unsaturated; saturated with max H; unsaturated have double bonds.

Proteins

Polymers of amino acids; perform structural, transport, and catalytic roles.

Amino acids

Monomers of proteins; 20 types; each with amino group, carboxyl group, and R group.

Peptide bonds

Bonds linking amino acids; formed by dehydration synthesis.

Primary structure

Amino acid sequence of a protein.

Secondary structure

Regions of folding: alpha-helix or beta-pleated sheet.

Tertiary structure

Overall 3D folding of a single polypeptide.

Quaternary structure

Interactions between two or more polypeptides.

Denaturation

Loss of protein structure and function.

Enzymes

Biological catalysts; speed reactions by lowering activation energy; usually proteins; have an active site.

Active site

Site on an enzyme where the substrate binds.

Activation energy

Minimum energy required for a reaction to occur.

Nucleic acids

DNA and RNA—the carriers of genetic information and protein synthesis.

DNA

Double-stranded, helical molecule that stores genetic code.

RNA

Single-stranded molecule involved in protein synthesis.

Nucleotides

Monomers of DNA/RNA; consist of phosphate group, sugar, and base.

Purines

Adenine and Guanine.

Pyrimidines

Cytosine, Thymine (DNA), Uracil (RNA).

ATP

Adenosine triphosphate; energy currency of the cell; energy stored in phosphate bonds.

Monomers

Individual units that bond to form polymers.

Polymers

Long chains formed by linking monomers.

Electrolyte

Dissolved ions that conduct electricity; essential for nerves and muscles.