Advanced Biology Unit 2: Atoms and Molecules

Vocabulary practice flashcards covering atomic structure, chemical bonding, water properties, macromolecules, and organic reactions from Advanced Biology Unit 2.

Essential Elements of Macromolecules

The six chemical elements required to build macromolecules: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, and Sulfur ($\text{CHONPS}$).

Electron

A negatively charged subatomic particle found orbiting outside the nucleus of an atom; its distribution accounts for almost all of the atom's volume.

Atomic Mass

The sum of the protons and neutrons in an atom's nucleus (e.g., an atom with $7$ protons, $8$ neutrons, and $7$ electrons has an atomic mass of $15$).

Valence Electrons

The electrons located in an atom's outermost shell whose arrangement determines the atom's capacity to form chemical bonds.

Proton

A positively charged subatomic particle residing in the nucleus; the total number of protons defines an atom's elemental identity.

Isotopes

Atoms of the same element that share identical numbers of protons but differ in their number of neutrons, such as Nitrogen-$14$ and Nitrogen-$15$.

Carbon-14

An isotope of carbon with an atomic mass of $14$ and an atomic number of $6$, containing $6$ protons, $6$ electrons, and $8$ neutrons.

Polar Covalent Bond

A chemical bond formed by the unequal sharing of electrons, such as the covalent bonds connecting the oxygen atom to the two hydrogen atoms within a single water molecule.

Hydrogen Bond (Water)

A weak intermolecular attraction holding neighboring water molecules together, responsible for water's ability to maintain a relatively stable temperature despite heat changes.

Nonpolar Covalent Bond

A covalent bond formed between two atoms of identical electronegativity (such as the double bond between oxygen atoms in an $O_2$ molecule), resulting in equal electron sharing.

Chemical Reactants and Products

In a chemical reaction such as $2\,H_2O \rightarrow 2\,H_2 + O_2$, $H_2O$ functions as the reactant while $H_2$ and $O_2$ function as the products.

Adhesion

The property of water molecules sticking to different substances or surfaces, such as plant cell walls, aiding capillary action up roots.

Cohesion

The property of water molecules sticking to one another via hydrogen bonding, forming a continuous column of water moving up a plant.

Solvent and Solute

In a saltwater solution, water is the solvent (the dissolving liquid) and the dissolved salts represent the solutes.

Base

A chemical compound that accepts $H^+$ ions, making an environment more basic and causing the solution's pH to increase.

Acid Neutralization

The reaction of an antacid (such as Tums) with stomach acid, which reduces the number of free-floating hydrogen ions ($H^+$ / protons).

Organic Compound

Any chemical substance that always contains carbon atoms.

Dehydration Synthesis

A reaction that covalently links two monomers together with the removal of a water molecule ($H_2O$), reversing the products of hydrolysis.

Hydrolysis

A chemical reaction that breaks the covalent bond between monomers through the addition of a water molecule.

Maltose

A disaccharide with the chemical formula $C_{12}H_{22}O_{11}$ formed from two glucose monomers ($C_6H_{12}O_6$) by dehydration synthesis, yielding one molecule of $H_2O$.

Monosaccharide

The monomer of carbohydrates, composed of Carbon, Hydrogen, and Oxygen ($\text{C, H, O}$) in ring or chain forms (e.g., glucose).

Cellulose

A structural polysaccharide made of glucose monomers that forms the rigid cell walls of plants.

Phospholipid

A lipid consisting of a hydrophilic head (glycerol and phosphate group) and two hydrophobic fatty acid tails, containing $\text{C, H, O, P}$.

Triglyceride

A lipid macromolecule constructed from a single glycerol molecule attached to three fatty acid chains, composed of $\text{C, H, O}$.

Amino Acid

The monomer of proteins, composed of $\text{C, H, O, N, S}$, containing an amino group, a central carbon, and a carboxylic acid group.

Protein Denaturation

The loss of a protein's three-dimensional shape and function, induced by increases in environmental temperature, shifts in pH, or changes in salt concentration.

Nucleotide

The monomer of nucleic acids, composed of $\text{C, H, O, N, P}$ and structured from three components: a five-carbon sugar, a phosphate group, and a nitrogenous base.

DNA (Deoxyribonucleic Acid)

A double-stranded nucleic acid containing deoxyribose sugar, phosphate, and the nitrogenous bases adenine, cytosine, guanine, and thymine.

Palmitic Acid

A saturated fatty acid with only single carbon-carbon bonds; its straight hydrocarbon chains pack tightly together, generating higher intermolecular attractions that make it solid at room temperature.

Linoleic Acid

An unsaturated fatty acid containing carbon-carbon double bonds that introduce bends or kinks, preventing close molecular packing and keeping it liquid at room temperature.