Chemical Components of Cells and Protein Structure & Function

Vocabulary flashcards generated from lecture notes covering atomic chemistry, chemical bonding, organic building blocks, nucleotide energy storage, protein folding, and enzymatic regulation.

Atom

The smallest particle of an element or molecule that still carries distinctive chemical properties.

Atomic Number

The total number of protons located within the positively charged nucleus of an atom.

Ionic Bond

A bond formed when an atom lacking a full outer shell donates an electron to another, creating a positive ion and a negative ion that balance out to crystallize into salt.

Covalent Bond

A bond formed when unstable atoms lacking filled outer shells share their electrons as a collective.

Double Covalent Bond

A bond created when two atoms share $2$ pairs of electrons, which restricts rotation and brings the bound atoms closer together.

Hydrogen Bond

A weak interaction formed between polar molecules containing hydrogen, such as adjacent $\text{H}_2\text{O}$ molecules.

Solute

A substance that is dissolved in a liquid solvent, such as salts and sugars.

Solvent

The liquid in a solution that dissolves a solute, such as $\text{H}_2\text{O}$.

Hydrophilic Molecules

Water-loving molecules, such as salts and sugars, that carry charges or polar groups and readily dissolve in water.

Hydrophobic Molecules

Water-fearing molecules, such as non-polar hydrocarbons, that do not mix with $\text{H}_2\text{O}$.

Monosaccharide

The smallest building block unit of sugar, containing $3$ to $6$ carbon atoms.

Condensation

A chemical reaction where sugar or amino acid monomers form covalent bonds with each other through the expulsion/release of an $\text{H}_2\text{O}$ molecule.

Hydrolysis

A chemical reaction that breaks down molecular bonds through the consumption of an $\text{H}_2\text{O}$ molecule.

Glycosidic Bond

The linkage formed between sugar molecules through a condensation reaction.

Saturated Hydrocarbon

A hydrocarbon chain with no double hydrogen bonds, creating straight tails that can cause backups and blockage (unhealthy)

Unsaturated Hydrocarbon

A hydrocarbon chain containing double hydrogen bonds that introduce kinks into the hydrophobic tail. (Healthy)

Triacylglycerol

A lipid molecule composed of $3$ hydrocarbon fatty acid chains attached to glycerol.

Phospholipid Molecule

A cell membrane component consisting of glycerol bound to $2$ fatty acid tails and a polar phosphate head group.

Amino Acid

The building block of proteins consisting of an amino group (e.g., $\text{NH}_2$), a carboxylic acid group (e.g., $\text{COOH}$), a central carbon, and a specific side ($R$) group.

Nucleotide

The structural unit of nucleic acids consisting of a nitrogenous base, a sugar (ribose or deoxyribose), and a phosphate group (phosphorus + $3$ oxygens).

Adenosine Triphosphate (ATP)

A nucleotide formed by Adenine, Ribose, and three phosphate groups that releases energy for intracellular work when converted to ADP and inorganic phosphate.

Polypeptide Backbone

The repeating sequence of carbon and nitrogen atoms linked by peptide bonds in a protein, bounded by an amino-terminus ($\text{N}$-terminus) and a carboxyl-terminus ($\text{C}$-terminus).

Chaperone Proteins

Specialized proteins that guide the folding of newly synthesized proteins along the most energy-favorable pathway.

Disulfide Bond

A covalent linkage formed between the sulfur-containing $\text{SH}$ groups of cysteine amino acid side chains to help stabilize a favored protein conformation.

Primary Structure

The first level of protein structure, defined by the linear sequence of amino acids.

Secondary Structure

Regular folding patterns within a polypeptide chain consisting of Alpha ($\alpha$) helices and Beta ($\beta$) sheets.

Tertiary Structure

The full three-dimensional conformation of a single polypeptide chain.

Quaternary Structure

A complex protein structure composed of more than one polypeptide chain subunit, such as hemoglobin with its $\alpha$- and $\beta$-globin subunits.

Denaturation

The unfolding or destruction of a protein's functional 3D conformation caused by environmental conditions like altered pH or temperature that disrupt non-covalent bonds.

Prion

A misfolded protein that causes neurodegenerative disease by converting normal proteins into misfolded prions that aggregate into amyloid structures.

Ligand

Any molecule that selectively binds to a protein's binding site using non-covalent interactions.

Substrate

A specific ligand molecule that binds to an enzyme's active site to be catalyzed into a product.

Feedback Inhibition

A regulatory mechanism in enzymatic pathways where an accumulation of an end product inhibits an enzyme earlier in the pathway to prevent overproduction.