Biology Chapter on Macromolecules and Hydrogen Bonding

Hydrogen Bonding

• Water molecules interact through hydrogen bonds, where the positive region of one molecule attracts the negative region of another
• Hydrogen bonding contributes to water's properties as a solvent, allowing it to dissolve polar molecules like salt
• Oil, being nonpolar, cannot participate in hydrogen bonding and separates from water

Macromolecules and Polymerization

• Macromolecules are responsible for the form and function of living organisms
• Cells contain three types of macromolecules: informational (DNA, RNA), storage (starch, glycogen), and structural (cellulose)
• Biological polymers (proteins, nucleic acids, polysaccharides) are formed by condensation reactions, releasing a water molecule

Carbohydrates

• Most abundant organic compounds in living organisms
• Simple sugars and polysaccharides play roles in energy storage and structural support
• Glucose is the most important monosaccharide, known as blood sugar and dextrose
• Fructose is a ketose sugar found in honey and fruit juices
• Disaccharides are formed from two simple sugars, examples include sucrose, maltose, and lactose
• Oligosaccharides are short chains of simple sugars found on cell membranes, involved in cell-cell recognition
• Polysaccharides are polymers of simple sugars, typically insoluble in water

Starch

• Major form of stored carbohydrate in plants
• Composed of amylose (linear) and amylopectin (branched)
• Both are polymers of α-D-Glucose

Glycogen

• Stored form of glucose in animal tissues
• Similar to amylopectin but with shorter, more frequent branches
• Easily converted back to glucose for energy

Cellulose

• Polymer of β-D-Glucose, forming long, unbranched chains
• Major structural material in plants, found in wood and cotton
• Difficult to digest by humans

Chitin

• Unbranched polymer of N-Acetyl-D-glucosamine
• Found in fungi and arthropod exoskeletons
• Similar to cellulose but with an acetamido group replacing the hydroxyl group

Glycosaminoglycans

• Found in lubricating fluids, cartilage, bone, and heart valves
• Long, unbranched polysaccharides with repeating disaccharide units containing amino sugars and uronic acids

Nucleic Acids

• Carry genetic information
• Polymers of nucleotides
• Nucleotides consist of a sugar (deoxyribose in DNA, ribose in RNA), a phosphate group, and a nitrogenous base
• DNA contains four bases: adenine, guanine, cytosine, and thymine; RNA has uracil instead of thymine
• Nucleotides are linked by phosphodiester bonds, forming a polynucleotide chain with a 5' to 3' direction
• ATP is a nucleotide that serves as the energy carrier in cells

Proteins

• Carry out instructions encoded in nucleic acids
• Diverse in function, serving as structural components, transporters, hormones, antibodies, and enzymes
• Polymers of 20 different amino acids
• Amino acids consist of a central carbon, a carboxyl group, an amino group, and a side chain

Thermodynamics

• Free energy change (ΔG) determines the direction of a chemical reaction
• Negative ΔG indicates a spontaneous forward reaction
• Positive ΔG indicates a spontaneous reverse reaction
• ΔG = 0 indicates equilibrium
• Standard free-energy change (ΔG°) is a measure of the free energy change under standard conditions

Coupled Reactions and ATP

• Energy-releasing reactions are coupled to energy-requiring reactions
• ATP is the main energy carrier in cells
• Hydrolysis of ATP to ADP and Pi releases free energy
• ATP is regenerated from ADP and Pi by photosynthesis in plants and metabolism in most cells

This quiz covers crucial concepts related to hydrogen bonding in water and the role of macromolecules in living organisms. It explores the types of macromolecules, their functions, and the significance of carbohydrates. Test your understanding of how these biochemical concepts interconnect.