Biology: Biomolecules

Carbohydrates

• Definition: Carbohydrates are biological molecules composed of carbon, hydrogen, and oxygen atoms, typically in a 1:2:1 ratio.
• Functions:
  • Provide energy for cells
  • Serve as structural components of cells
  • Act as energy storage molecules
• Types:
  • Monosaccharides: Simple sugars, e.g., glucose, fructose
  • Disaccharides: Composed of two monosaccharides, e.g., sucrose (glucose + fructose)
  • Polysaccharides: Composed of many monosaccharides, e.g., starch, cellulose

Proteins

• Definition: Proteins are biological molecules composed of amino acids, which are the building blocks of proteins.
• Functions:
  • Catalyze metabolic reactions as enzymes
  • Regulate gene expression
  • Maintain cell shape and structure
  • Transport molecules across cell membranes
  • Respond to stimuli
• Structure:
  • Primary structure: Sequence of amino acids
  • Secondary structure: Local arrangements of amino acids, e.g., alpha helix, beta sheet
  • Tertiary structure: Overall 3D shape of the protein
  • Quaternary structure: Interaction between multiple polypeptide chains

Lipids

• Definition: Lipids are biological molecules that are insoluble in water and are composed of carbon and hydrogen atoms, with or without oxygen, nitrogen, and other elements.
• Functions:
  • Energy storage
  • Cell membrane structure
  • Hormone regulation
  • Vitamin absorption
• Types:
  • Fats: Energy storage molecules, e.g., triglycerides
  • Phospholipids: Major component of cell membranes, e.g., phosphatidylcholine
  • Steroids: Hormone regulation, e.g., cholesterol

Polysaccharides

• Definition: Polysaccharides are carbohydrates composed of many monosaccharides linked together.
• Types:
  • Starch: Energy storage molecule in plants
  • Cellulose: Structural component of plant cell walls
  • Glycogen: Energy storage molecule in animals
• Functions:
  • Energy storage
  • Structural components of cells

Nucleic Acids

• Definition: Nucleic acids are biological molecules that contain the genetic information of an organism.
• Types:
  • DNA (Deoxyribonucleic acid): Genetic information storage
  • RNA (Ribonucleic acid): Transcription and translation of genetic information
• Structure:
  • Double helix: DNA double-stranded structure
  • Nucleotides: Building blocks of nucleic acids, composed of a sugar, phosphate group, and nitrogenous base