Chemical Structures of Biomolecules

Chemical Structures of Biomolecules

Key Points:

• Biomolecules are organic molecules essential for life, forming the structural components and performing vital functions within living organisms.
• Four major classes of biomolecules exist: carbohydrates, lipids (fats), proteins, and nucleic acids.
• The structure of a biomolecule dictates its function. This is particularly evident in proteins, where the amino acid sequence determines the three-dimensional structure, which in turn defines its activity.
• Enzymes are proteins that act as biological catalysts, significantly increasing the rate of biochemical reactions.
• The shape and chemical properties of an enzyme's active site are crucial for substrate binding and catalysis.

Main Concepts:

1. What are biomolecules? Biomolecules are large organic molecules found in living organisms, including carbohydrates, lipids, proteins, and nucleic acids. They are synthesized by living organisms and perform a wide array of functions.
2. What are the four main types of biomolecules?
   • Carbohydrates: Composed of carbon, hydrogen, and oxygen, often in a 1:2:1 ratio. Exist as monosaccharides (simple sugars), disaccharides (two monosaccharides linked), and polysaccharides (long chains of monosaccharides). Function as energy sources and structural components.
   • Lipids (Fats): Primarily composed of carbon, hydrogen, and oxygen, but with a much lower proportion of oxygen than carbohydrates. Include triglycerides (energy storage), phospholipids (cell membranes), and steroids (hormones). Function in energy storage, insulation, and cell membrane structure.
   • Proteins: Polymers of amino acids linked by peptide bonds. The sequence of amino acids determines the protein's three-dimensional structure and function. Functions are diverse, including catalysis (enzymes), structural support, transport, and defense.
   • Nucleic Acids: Polymers of nucleotides, consisting of a sugar (ribose or deoxyribose), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, thymine, or uracil). DNA and RNA are examples, carrying genetic information and directing protein synthesis.
3. What are the structures of carbohydrates, lipids, proteins, and nucleic acids? The structures are detailed above in point 2. Further detail would require diagrams and more extensive descriptions of specific examples (e.g., alpha vs beta glucose, saturated vs unsaturated fatty acids, primary, secondary, tertiary, and quaternary protein structure, DNA double helix).
4. What are the functions of carbohydrates, lipids, proteins, and nucleic acids? The functions are detailed above in point 2.
5. How do enzymes work? Enzymes work by binding to specific substrates at their active site. This binding lowers the activation energy of the reaction, allowing it to proceed much faster. The enzyme is not consumed in the reaction and can be used repeatedly.
6. What are the factors that affect enzyme activity? Several factors influence enzyme activity, including temperature, pH, substrate concentration, enzyme concentration, and the presence of inhibitors or activators.