Biological Molecules - Carbohydrates, lipids and proteins

Carbohydrates are organic compounds consisting of Carbon ($C$), Hydrogen ($H$), and Oxygen ($O$), usually in a $2:1$ ratio of Hydrogen to Oxygen.

Monosaccharides like glucose ($C_6H_{12}O_6$) are the monomers of carbohydrates; they can exist as $\alpha$-glucose or $\beta$-glucose isomers.

Disaccharides are formed when two monosaccharides join via a condensation reaction, creating a glycosidic bond and releasing a molecule of water ($H_2O$).

Polysaccharides such as starch and glycogen serve as energy storage, while cellulose (made of $\beta$-glucose) provides structural support in plant cell walls.

Lipids (triglycerides) are formed from one glycerol molecule and three fatty acids joined by ester bonds through the process of esterification.

Fatty acids can be saturated (no double bonds between carbons) or unsaturated (containing one or more $C=C$ double bonds).

Proteins are polymers of amino acids; each amino acid contains an amino group ($-NH_2$), a carboxyl group ($-COOH$), and a variable $R$ group.

Amino acids are linked by peptide bonds formed between the $-NH_2$ of one and the $-COOH$ of another.

The 3D shape of a protein is determined by its primary sequence and maintained by hydrogen bonds, ionic bonds, disulfide bridges ($-S-S-$), and hydrophobic interactions.

The Benedict's test is used for reducing sugars (color change from blue to brick-red), while the Biuret test detects peptide bonds in proteins (blue to purple).