Chemical Level of Organization Flashcards

Vocabulary flashcards covering fundamental terms, concepts, chemical structures, and reactions from the Chemical Level of Organization lecture notes.

Matter

Anything that occupies space and has mass.

Mass

The amount of matter contained in an object, which remains constant whether on Earth or in zero gravity.

Weight

The measure of matter that varies based on the influence of gravity.

Element

A pure substance that cannot be created or broken down by ordinary chemical means.

Compound

A substance composed of two or more elements joined by chemical bonds in fixed relative amounts.

Atom

The smallest quantity of an element that retains the unique properties of that element.

Atomic Number

The total number of protons in the nucleus of an atom, which uniquely identifies the element.

Mass Number (Atomic Mass)

The sum of the total number of protons and neutrons in the nucleus of an atom.

Isotope

One of the differing structural forms of an element that has the same number of protons but a different number of neutrons.

Radioactive Isotope

An unstable isotope with extra neutrons whose nucleus readily decays, releasing subatomic particles and electromagnetic energy.

Valence Shell

An atom's outermost electron shell, the electron content of which primarily governs its chemical reactivity.

Octet Rule

The principle stating that an atom is most stable when its valence shell contains exactly $8$ electrons.

Molecule

An entity composed of two or more atoms held together by chemical bonds.

Ion

An atom or molecule with a positive or negative electrical charge resulting from the loss or gain of one or more electrons.

Cation

A positively charged ion formed when an atom donates one or more electrons.

Anion

A negatively charged ion formed when an atom accepts one or more electrons.

Ionic Bond

An ongoing mutual attraction between oppositely charged cations and anions.

Electrolytes

Dissolved ions in biological fluids that produce electrical charges capable of conducting electrical currents in solution.

Nonpolar Covalent Bond

A chemical bond formed when two atoms share valence electrons equally, resulting in an electrically balanced molecule.

Polar Covalent Bond

A chemical bond formed when atoms share electrons unequally, resulting in regions of slight partial positive and partial negative charge.

Hydrogen Bond

A weak attraction between a weakly positive hydrogen atom in a polar molecule and an electronegative atom in another molecule.

Anabolism

Metabolic chemical reactions that build larger, more complex molecules from smaller molecules or atoms.

Catabolism

Metabolic chemical reactions that break bonds in larger molecules, releasing smaller molecules or atoms.

Kinetic Energy

The form of energy powering matter that is in motion.

Potential Energy

The form of energy matter possesses due to the positioning or chemical structure of its components.

Chemical Energy

A form of potential energy stored within the chemical bonds between atoms and molecules.

Mechanical Energy

A form of kinetic energy that directly powers the movement of matter.

Radiant Energy

Kinetic energy emitted as electromagnetic waves traveling through space.

Electrical Energy

Energy supplied by electrolytes in cells and body fluids that powers voltage changes in nerve and muscle cells.

Reactants

The starting substances that enter into a chemical reaction.

Products

The substances produced as a result of a chemical reaction.

Activation Energy

The threshold level of energy needed to ignite and proceed with a chemical reaction.

Catalyst

A substance that increases the rate of a chemical reaction without itself undergoing any permanent change.

Enzyme

A biological catalyst composed of protein or RNA that lowers the activation energy of a chemical reaction.

Inorganic Compound

A substance that does not contain both carbon and hydrogen atoms, such as water, salts, acids, and bases.

Organic Compound

A carbon-based substance containing both carbon and hydrogen synthesized via covalent bonds in living organisms.

Acid

A substance that releases hydrogen ions ($H^+$) into solution, lowering the solution's pH below $7$.

Base

A substance that releases hydroxyl ions ($OH^-$) or accepts hydrogen ions ($H^+$) in solution, raising the pH above $7$.

Buffer

A system comprising a weak acid and its conjugate base that resists shifts in pH by neutralizing added acids or bases.

Acidosis

A condition characterized by excessive acidity of the blood and body fluids, typically resulting from accumulated $CO_2$ and $H^+$.

Alkalosis

A condition characterized by excessive alkalinity of the blood and body fluids, occurring when $CO_2$ and $H^+$ levels drop too low.

Monosaccharide

A single monomer sugar, such as glucose, fructose, galactose, ribose, or deoxyribose, that serves as an absorbable carbohydrate unit.

Disaccharide

A carbohydrate formed by joining two monosaccharides through dehydration synthesis, such as sucrose, lactose, or maltose.

Polysaccharide

A complex carbohydrate polymer composed of many linked monosaccharides, such as starch, glycogen, or cellulose.

Triglyceride

A lipid molecule composed of a glycerol backbone attached to three fatty acid chains.

Saturated Fatty Acid

A fatty acid chain with maximum hydrogen atoms and single carbon bonds, forming a straight, rigid structure that is solid at room temperature.

Unsaturated Fatty Acid

A fatty acid chain missing hydrogen atoms that contains one or more double carbon bonds ($C=C$), creating kinks that keep it liquid at room temperature.

Phospholipid

A lipid containing a glycerol backbone bound to two hydrophobic fatty acid tails and a polar hydrophilic phosphate group head.

Sterol

A lipid structure featuring four interlocking hydrocarbon rings, with cholesterol being the primary example in human physiology.

Prostaglandin

A lipid derivative of unsaturated fatty acids that acts as a local vasodilator and mediates inflammation, pain sensitivity, and cervical softening.

Primary Protein Structure

The fundamental linear sequence of amino acids linked together by peptide bonds.

Secondary Protein Structure

The localized folding of a polypeptide chain into an $\alpha\text{-helix}$ or $\beta\text{-pleated sheet}$, stabilized by hydrogen bonds.

Tertiary Protein Structure

The compact, three-dimensional folding of a single polypeptide chain held in place by hydrogen bonds and disulfide bonds.

Quaternary Protein Structure

The complex structure formed when two or more distinct polypeptide subunits bond together.

Denaturation

A physical or chemical change in a protein's structure that causes it to lose its functional shape and biological activity.

Active Site

The specific region on an enzyme where reactant substrate molecules bind to undergo a catalyzed reaction.

Nucleotide

A monomer unit consisting of one or more phosphate groups, a pentose sugar, and a nitrogen-containing base.

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid forming a double helix that contains genetic code stored in adenine, thymine, cytosine, and guanine base pairs.

RNA (Ribonucleic Acid)

A single-stranded nucleic acid containing ribose and uracil that functions to translate genetic instructions into proteins.

ATP (Adenosine Triphosphate)

A high-energy compound composed of ribose, adenine, and three phosphate groups that serves as the primary energy currency of cells.

Phosphorylation

The addition of a phosphate group ($P_i$) to an organic compound, such as reattaching a phosphate to ADP to synthesize ATP.