Biomolecules - Structure and function of Proteins, Carbohydrates, Lipids, Nucleic acids

Biomacromolecules are large organic compounds with molecular weights exceeding $1000$ Daltons, found in the acid-insoluble fraction during chemical analysis.

Carbohydrates are polyhydroxy aldehydes or ketones. Monosaccharides are linked by glycosidic bonds formed by dehydration synthesis between two carbon atoms (usually $C_1$ and $C_4$).

Proteins are heteropolymers of amino acids. Each amino acid contains an amino group ($-NH_2$), a carboxyl group ($-COOH$), and a variable $R$ group attached to the $\alpha$-carbon.

Protein structure levels: Primary (linear sequence), Secondary ($\alpha$-helix or $\beta$-pleated sheets via $H$-bonds), Tertiary (3D folding via disulfide bridges and ionic bonds), and Quaternary (assembly of multiple polypeptide chains).

Lipids are generally water-insoluble and include fatty acids and glycerol. Triglycerides are formed by the esterification of three fatty acids to one glycerol molecule via ester bonds.

Nucleic acids (DNA and RNA) are polymers of nucleotides. Each nucleotide consists of a pentose sugar, a nitrogenous base, and a phosphate group linked by phosphodiester bonds.

In DNA, the nitrogenous bases follow Chargaff's rule where Purines ($A, G$) always pair with Pyrimidines ($T, C$) through hydrogen bonds ($A=T$ and $G\equiv C$).