CHAP 2

Flashcards covering key vocabulary and concepts from the Chemical Level of Organization lecture notes.

Matter

Anything that takes up space and has mass.

Mass

The quantity of material in matter; on Earth, equivalent to weight.

Atoms

Smallest stable units of matter.

Protons (p+)

Have a positive electrical charge.

Neutrons (n or n0)

Electrically neutral (uncharged).

Electrons (e–)

Have a negative electrical charge and are much smaller than protons or neutrons.

Nucleus

The center of an atom, containing one or more protons and may also contain neutrons.

Electron cloud

Created by the whirl of electrons around the nucleus.

Atomic number

Total number of protons in an atom.

Mass number

Total number of protons and neutrons in an atom.

Element

Substance composed only of atoms with the same atomic number.

Isotopes

Atoms with the same number of protons but different numbers of neutrons; have identical chemical properties but different mass numbers.

Atomic mass

Actual mass of an atom of a specific isotope, measured in atomic mass units (amu) or daltons.

Atomic weight

Equals average mass of an element, including different isotopes in proportion.

Principal elements

Thirteen most abundant elements by body weight

Trace elements

Fourteen other elements present in the body in very small amounts

Valence Shell

Outermost energy level of an electron shell.

Ions

Atoms that have gained or lost electrons are no longer electrically neutral and become ____.

Cation

Positive ion.

Anion

Negative ion.

Compounds

Chemical substance made up of atoms of two or more different elements in a fixed proportion.

Molecules

Chemical structure consisting of atoms of one or more elements held together by covalent bonds.

Ionic bonds

Created by electrical attraction between cations and anions involving the transfer of one or more electrons from one atom to another

Covalent bonds

Involve sharing of electrons between atoms.

Nonpolar molecule

Electrons shared equally between atoms, no electrical charge on the molecule

Polar molecule

Unequal sharing of electrons between atoms.

Solid

Maintains volume and shape at ordinary temperatures and pressures.

Liquid

Has a constant volume; container determines shape.

Gas

Has neither a constant volume nor a fixed shape; can be compressed or expanded and will fill a container of any size.

Hydrogen bond

Attraction of the small positive charges on hydrogen atoms (of a polar molecule) to negative charges on atoms in other polar molecules.

Solvent

The liquid in which other atoms, ions, or molecules are distributed.

Solute

The dissolving substances

Solution

A uniform mixture of two or more substances

Aqueous solutions

Where water is the solvent

Metabolism

All of the reactions in the body at any moment

Work

Movement of an object or change in physical structure of matter.

Energy

Capacity to perform work.

Kinetic energy

Energy of motion.

Potential energy

Stored energy.

Reactants

Participants at reaction start, usually on the left

Products

Generated at end of reaction, usually on the right

Mole (mol)

Quantity with a weight (in grams) equal to an element’s atomic weight.

Molecular weight

Sum of the atomic weights of all atoms making up a molecule; for ionic compounds, use the term formula weight.

Decomposition reactions

Break a molecule into smaller fragments

Hydrolysis

Specific type of decomposition reaction that involves water.

Catabolism

Collective term for decomposition reactions in the body

Synthesis reactions

Assemble smaller molecules into larger molecules

Dehydration synthesis (condensation)

Formation of a complex molecule by removing a water molecule.

Anabolism

Collective term for synthesis reactions.

Exchange reactions

Parts of the reacting molecules are shuffled around to produce new products.

Activation energy

Minimum energy required to activate reactants in a reaction and allow reaction to proceed

Enzymes

Special proteins cells use to promote chemical reactions

Catalysts

Accelerate chemical reaction without being permanently changed or consumed

Metabolic pathway

Series of complex reactions occurring in the body

Exergonic

Overall net release of energy

Endergonic

More energy is required to begin than is released

Metabolites

Substances synthesized or decomposed in our bodies

Nutrients

Essential metabolites normally obtained from our diet

Macromolecule

Large molecule made up of monomer subunits

Monomer

Molecule that can be bonded to other identical molecules to form a polymer

Water

Most important component of your body Makes up about 2/3 of total body weight

Heat capacity

Quantity of heat required to raise temperature of a unit mass of a substance 1ºC

Thermal inertia

Refers to large mass of water changing temperature very slowly.

Ionization or dissociation

Process of breaking ionic bonds as ions interact with poles of a water molecule

Hydration spheres

A layer of water molecules around an ion in solution

Hydrophilic

Molecules that interact with water readily

Electrolytes

Soluble inorganic substances whose ions will conduct electrical current

Hydrophobic

Do not readily interact with water

Colloid

Solution containing dispersed proteins or other large molecules

Suspension

Solution containing larger particles

pH

Measure of H+ concentration in body fluids (negative logarithm in mol/L)

Acid

Solute that dissociates and releases hydrogen ions

Base

Solute that removes hydrogen ions from solution

Salt

Inorganic compound composed of any cation (except hydrogen) and any anion (except hydroxide

Buffers

Compounds that stabilize the pH of a solution by removing or replacing hydrogen ions

Organic compounds

Always contain carbon and hydrogen and generally oxygen

Functional groups

Attached groupings of atoms that occur commonly in many organic molecules

Carbohydrates

Organic molecules containing carbon, hydrogen, and oxygen in ratio near 1:2:1

Monosaccharide

Simple sugar

Isomers

Molecules with the same molecular formula but different structures

Disaccharide

Two monosaccharides joined

Polysaccharides

Complex carbohydrates formed from multiple disaccharides and/or monosaccharides

Lipids

Contain carbon, hydrogen, and oxygen

Fatty acids

Long carbon chains with attached hydrogen atoms

Saturated fatty acid

Each carbon in the tail has four attached hydrogens

Unsaturated fatty acid

Contains double bonds in the tail

Glycerides

Fatty acid chains attached to a glycerol molecule

Eicosanoids

Lipids derived from arachidonic acid

Steroids

Large molecules with four carbon rings

Phospholipid

Phosphate linking a diglyceride to a nonlipid group

Glycolipid

Carbohydrate attached to a diglyceride

Proteins

Most abundant organic molecule in the body

Peptides

Amino acids linked through dehydration synthesis

Denaturation

Change in protein tertiary or quaternary structure

Active site

Specific region of an enzyme where substrates must bind

Substrates

Reactants in enzymatic reactions

High-energy compounds

Donate energy to enzymatic reactions to form products

Adenosine triphosphate (ATP)

Most common high-energy compound

Nucleic acids

Large organic molecules composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus

Deoxyribonucleic acid

DNA