Biological Macromolecules and Reactions

Biological Macromolecules

• Large molecules vital for living organisms
• Involved in providing building blocks, energy, and genetic information
• Imbalances can negatively affect health
• Examples include: excess fat leading to cardiovascular problems, and excess protein straining the kidneys
• Important for overall health to maintain a balanced diet

Dehydration Synthesis and Hydrolysis

• Dehydration synthesis (condensation reactions): Anabolic reactions that involve the removal of a single water molecule to combine two or more molecules, forming a larger molecule, an important process in biology
• Hydrolysis reactions: Catabolic reactions that involve the addition of water molecules to break down larger molecules, releasing energy stored in macromolecules like sugars, proteins, and fats, important in digestion
• Both reactions crucial in the synthesis and breakdown of macromolecules in living organisms
• Example of dehydration synthesis: the linking of two glucose molecules to form maltose.
• Example of hydrolysis reactions: the breakdown of carbohydrates, proteins, and fats for energy.

Carbohydrates

• One of the main biomolecules in living organisms
• Primary source of energy for the body
• Provide structural support
• Types:
  • Monosaccharides: Simple sugars (e.g., glucose, fructose, galactose) that cannot be broken down into smaller sugars.
  • Disaccharides: Two monosaccharides linked together (e.g., sucrose, lactose, maltose).
  • Polysaccharides: Complex carbohydrates composed of many monosaccharide units (e.g., starch, glycogen, cellulose) used for energy storage and structural support.

Amino Acids

• Building blocks of proteins
• Essential for life
• Each amino acid has a specific structure with a central chiral carbon atom bonded to four different substituents: an amino group, a carboxyl group, a hydrogen atom, and a variable side chain
• Unique side chains (R groups) determine their characteristics and functions.
• Example: Glycine is an exception, lacking a chiral carbon

Primary Structure of Proteins

• Linear sequence of amino acids
• Amino acids joined via peptide bonds forming a chain
• Important in determining the overall shape of the protein
• Crucial for protein function

Secondary Structure of Proteins

• Regular pattern or shape formed from hydrogen bonds between amino acids
• Two main forms: alpha helix (spiral) and beta pleated sheet (flat)
• These forms help stabilize the structure

Tertiary Structure of Proteins

• Further folding of the protein into a three-dimensional shape
• Interactions between amino acid side chains (R groups), including hydrophobic and hydrophilic interactions, hydrogen bonds, disulfide bridges, and van der Waals forces
• Determines the overall function of the protein.

Quaternary Structure of Proteins

• Two or more polypeptide chains (proteins) interacting to form a larger complex
• Multiple protein subunits working together
• Example: Hemoglobin

Hemoglobin Cooperative Binding

• Hemoglobin's ability to bind more oxygen at lower partial pressures
• Binding to oxygen to one subunit of hemoglobin changes the shape of the protein, making it easier for other subunits to bind oxygen.
• Importance in efficient oxygen transport in the body.

Globular and Fibrous Proteins

• Globular: Spherical, soluble in water, versatile functions (e.g., enzymes, hormones)
• Fibrous: Long, slender, insoluble in water, structural roles (e.g., collagen, keratin)

Lipids

• Diverse group of organic molecules
• Including fats, waxes, sterols, and certain oils.
• Dissolves in nonpolar solvents, not water.
• Saturated: No double bonds, solid at room temp, associated with high risk of heart disease.
• Unsaturated: One or more double bonds, liquid at room temp, associated with lower risk of heart disease.
• Triglycerides: Composed of three fatty acids and a glycerol molecule, important energy storage and membrane components.
• Phospholipids: Essential for cell membranes composed of fatty acid chains and a phosphate group, providing a barrier between cell’s interior and extracellular environment.
• Sterols: Typically composed of four fused rings, crucial for hormone synthesis and membrane fluidity (e.g., cholesterol)
• Waxes: Composed of long-chain fatty acid and alcohol, water-repellent, and used for protective functions in plants and animals.

Nucleic Acids

• DNA (deoxyribonucleic acid): Double-stranded helical molecule that carries genetic information and is crucial for passing genetic instructions from one generation to the next.
• RNA (ribonucleic acid): Single-stranded molecule responsible for protein synthesis and other vital processes in cells.
• Purines and Pyrimidines: Nitrogenous bases that form the building blocks of nucleic acids. Crucial in base pairing for DNA and RNA.