Biological Macromolecules: Carbohydrates, Lipids, and Proteins

Carbohydrates

• Monosaccharides: Glucose, ribose, fructose.
• Disaccharides: Maltose (two glucose molecules), sucrose (glucose and fructose).
• Polysaccharides: Cellulose and glycogen (chains of glucose).

Fatty Acids

• Cis-unsaturated fatty acids: Bended structure, loosely packed, low melting point, hydrogen atoms on the same side, liquid at room temperature, common in nature.
• Trans-unsaturated fatty acids: Straight structure, strongly packed, high melting point, hydrogen atoms on opposite sides, solid at room temperature, rare in nature.

Amino Acids and Proteins

Amino acids consist of an amino group (-NH2) and a carboxyl group (-COOH).

Common Amino Acids

Serine, glutamic acid, alanine, and glycine.

Amino Acid Structure

Amino acids linked together share identical structural features: a central carbon atom, a carboxyl group, and a hydrogen atom.

Genetic Codons

• UGA: Selenocysteine
• UAG: Pyrrolysine

Examples of Proteins

• Integrin: Membrane protein with two polypeptides.
• Collagen: Structural protein with three polypeptides.
• Hemoglobin: Transport protein with four polypeptides.
• Lysozyme: Enzymes in secretions that kill bacteria.

Protein Functions

• Catalysis: Enzymes catalyze specific chemical reactions.
• Muscle Contraction: Actin and myosin facilitate locomotion.
• Cytoskeletons: Tubulin subunits form microtubules for cell shape and chromosome movement during mitosis.
• Tensile Strengthening: Fibrous proteins provide strength to skin and tendons.
• Blood Clotting: Plasma proteins convert blood from liquid to gel.
• Transport: Proteins transport oxygen, carbon dioxide, iron, and lipids.
• Cell Adhesion: Membrane proteins allow adjacent animal cells to stick together.
• Membrane Transport: Facilitated diffusion, active transport, and electron transport.
• Hormones: Chemically diverse proteins such as insulin, FSH, and LH.
• Receptors: Binding sites for light, neurotransmitters, taste, and smell.
• DNA Packaging: Histones associated with DNA in eukaryotes.
• Immunity: The most diverse group of proteins.