Module 2.01: Biomacromolecules

Practice vocabulary flashcards covering the structure, elemental composition, linkage types, and functions of the four major biomacromolecules (carbohydrates, nucleic acids, proteins, and lipids).

CHNOPS

The primary chemical elements that compose living biomass: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur.

Polymer

A large molecule composed of multiple covalently linked, repeating subunits, where each class is defined by a shared chemical structure (such as nucleic acids, proteins, and glycans).

Lipids

A major class of biomolecules defined by a shared physical property (hydrophobicity/nonpolarity) rather than a shared chemical structure; they are not considered polymers and do not possess repeating subunits.

Condensation reaction (Dehydration reaction)

A chemical reaction that links monomers together into polymers by releasing a molecule of water ($\text{monomer in, water out}$).

Hydrolysis

A chemical reaction that breaks polymers down into individual monomer subunits through the addition of a water molecule ($\text{water in, monomer out}$).

Glycans (Polysaccharides)

Polymers of monosaccharides with the general chemical formula $(CH_2O)_n$ containing $C=O$, $OH$, and $C-H$ groups; functions include energy storage, structural integrity, and cell-cell signaling.

Starch

A plant energy storage polysaccharide composed of $\alpha$-glucose monomers joined by $\alpha$-1,4-glycosidic linkages, occurring as unbranched helices (amylose) or branched helices (amylopectin).

Glycogen

An animal energy storage polysaccharide stored in liver and muscle cells, consisting of highly branched helices of $\alpha$-glucose monomers joined by $\alpha$-1,4-glycosidic linkages.

Cellulose

A structural polysaccharide providing support in the cell walls of plants and many algae, consisting of parallel strands of $\beta$-glucose joined by $\beta$-1,4-glycosidic linkages and cross-linked by hydrogen bonds.

Chitin

A structural polysaccharide in fungal cell walls and insect/crustacean exoskeletons, consisting of $\beta$-1,4-glycosidic linked monomers with an $NHCOCH_3$ group, arranged in parallel strands joined by hydrogen bonds.

Peptidoglycan

A structural polysaccharide providing support in bacterial cell walls, consisting of $\beta$-1,4-glycosidic linked monomers with an $NHCOCH_3$ group, joined in parallel strands by peptide bonds between 4-amino-acid chains.

Glycoprotein

A membrane-associated conjugate of an oligosaccharide linked to a protein that functions on the extracellular surface for cell-cell recognition and signaling.

Phosphodiester linkage

The covalent bond in nucleic acids that joins the $3'$ carbon of one nucleotide's sugar to the $5'$ carbon of the adjacent nucleotide via a phosphate group.

Nucleic acid directionality

The asymmetric orientation of a nucleic acid chain running from the $5'$ end to the $3'$ end, where new nucleotides can only be added to the unlinked $3'$ carbon.

RNA (Ribonucleic acid)

A nucleic acid polymer composed of ribonucleotides containing uracil and a reactive $2'\text{ OH}$ group on ribose, typically single-stranded and capable of folding into complex tertiary structures that catalyze chemical reactions.

DNA (Deoxyribonucleic acid)

A double-stranded, antiparallel nucleic acid polymer containing deoxyribose and thymine, stabilized by base pairing via hydrogen bonds between complementary strands.

Peptide bond

The planar covalent bond formed between the carboxyl group ($COO^-$) of one amino acid and the amino group ($NH_3^+$) of another, exhibiting double-bond-like properties due to electron sharing.

Primary structure

The linear sequence of amino acids in a polypeptide chain, stabilized strictly by covalent peptide bonds along the backbone.

Secondary structure

Local polypeptide conformations, most commonly $\alpha$-helices and $\beta$-pleated sheets, stabilized by hydrogen bonding between carbonyl and amino groups along the peptide backbone.

Tertiary structure

The overall three-dimensional shape of a single polypeptide, stabilized by hydrogen bonds, hydrophobic interactions, van der Waals forces, ionic bonds, and covalent disulfide bonds between R-groups or between R-groups and the backbone.

Quaternary structure

The overall shape produced by the association of two or more distinct polypeptide subunits into a functional multi-protein complex, such as the tetramer hemoglobin.

Disulfide bond

A covalent linkage formed between the sulfur atoms of two cysteine side chains ($CH_2-S-S-CH_2$) that stabilizes tertiary or quaternary protein conformation.

Nonpolar amino acid side chains

Hydrophobic R-groups lacking charged or highly electronegative atoms (e.g., valine, leucine, tryptophan); insoluble in water and predominantly found buried in protein interiors or contacting membrane lipids.

Electrically charged acidic side chains

Negatively charged amino acid R-groups (Aspartate and Glutamate) that contain a carboxylate group, form hydrogen and ionic bonds, and are highly soluble in water.

Electrically charged basic side chains

Positively charged amino acid R-groups (Lysine, Arginine, and Histidine) that contain amino or nitrogenous groups, form hydrogen and ionic bonds, and are highly soluble in water.

Sickle cell hemoglobin mutation

A primary structure change substituting glutamate (negatively charged) with valine (hydrophobic) at position 6 of the $\beta$-globin chain, exposing a hydrophobic region that causes hemoglobin molecules to aggregate.

Fats (Triglycerides)

Lipid molecules consisting of a glycerol backbone linked to three fatty acid hydrocarbon chains via ester linkages formed by dehydration reactions.

Phospholipid

An amphipathic lipid consisting of glycerol linked to two hydrophobic fatty acid tails and a hydrophilic head containing a phosphate group and a polar/charged moiety; the primary component of cell membranes.

Steroid

A class of lipids characterized by a bulky four-ring carbon skeleton and an isoprene chain, possessing a small polar (hydrophilic) functional group and a nonpolar (hydrophobic) body.