Biological Molecules

• Why is water considered a polar molecule?


  Water is polar due to the uneven distribution of charge.
• What role does water play in metabolic reactions?


  Water acts as a metabolite in reactions such as condensation and hydrolysis.
• How does cohesion in water molecules benefit plants?


  Strong cohesion enables effective transport of water in tube-like transport cells.
• What are monomers and polymers in biological molecules?


  • Monomers: Small units like monosaccharides, amino acids, nucleotides.
  • Polymers: Larger molecules made from monomers joined together.
• What is a condensation reaction?


  A condensation reaction joins monomers by eliminating a water molecule.
• What is hydrolysis?


  Hydrolysis is the addition of water to break a chemical bond between two molecules.
• What are the three types of saccharides?

  • Monosaccharides
  • Disaccharides
  • Polysaccharides
• What is glucose and its significance?

  Glucose is a monosaccharide with six carbon atoms and is the main substrate for respiration.
• What are the two isomers of glucose?


  The two isomers of glucose are alpha and beta glucose.
• How is maltose formed?


  Maltose is formed by the condensation of two glucose molecules.
• What is sucrose and how is it formed?

  Sucrose is a disaccharide formed by the condensation of glucose and fructose.
• How is lactose formed?

  Lactose is formed by the condensation of glucose and galactose.
• What are the main polysaccharides and their formation?


  • Glycogen: Formed from alpha glucose.
  • Starch: Mixture of amylose and amylopectin from alpha glucose.
  • Cellulose: Formed from beta glucose.
• What is glycogen and its role in animals?

  Glycogen is the main energy storage molecule in animals, formed from alpha glucose.
• How is starch structured and its function in plants?


  Starch stores energy in plants and consists of amylose and amylopectin.
• What is amylose and its structure?

  Amylose is an unbranched chain of glucose molecules joined by 1,4 glycosidic bonds, making it compact.
• What is amylopectin and its structure?

  Amylopectin is a branched polysaccharide made of glucose molecules joined by 1,4 and 1,6 glycosidic bonds.
• What is cellulose and its role in plants?


  Cellulose is a component of cell walls in plants, made of long, unbranched chains of beta glucose.
• What are microfibrils and their function?


  Microfibrils are strong threads made of cellulose chains providing structural support in plant cells.
• What are the two types of lipids?

  • Saturated lipids
  • Unsaturated lipids
• What are saturated lipids?


  Saturated lipids do not contain any carbon-carbon double bonds.
• What are unsaturated lipids?


  Unsaturated lipids contain carbon-carbon double bonds and melt at lower temperatures.
• How does the number of unsaturated bonds affect melting point?


  The greater the number of unsaturated bonds, the lower the melting point due to weaker intermolecular bonds.
• What are triglycerides and their structure?


  Triglycerides are made of one glycerol molecule and three fatty acids joined by ester bonds.
• What is the function of triglycerides?


  Triglycerides are used as energy reserves in plant and animal cells.
• What are phospholipids and their structure?


  Phospholipids have one fatty acid replaced by a phosphate group, with hydrophilic heads and hydrophobic tails.
• How do phospholipids behave in water?


  Phospholipids form micelles in water, with hydrophilic heads outward and hydrophobic tails inward.
• What is the role of hydrogen ions in biological systems?


  Hydrogen ions determine the pH of substances like blood.
• What is the role of iron ions?


  Iron ions are a component of hemoglobin, which carries oxygen in red blood cells.
• What is the function of sodium ions?


  Sodium ions are involved in the co-transport of glucose and amino acids.
• What is the role of phosphate ions?


  Phosphate ions are components of DNA and ATP.
• What are amino acids and their structure?


  • Amino acids are monomers of proteins.
  • They contain an amino group (NH2), carboxylic acid group, and a variable R group.
• How many different amino acids are there?


  There are 20 different amino acids.
• How are amino acids joined together?


  Amino acids are joined by peptide bonds formed in condensation reactions.
• What is a dipeptide?


  A dipeptide contains two amino acids.
• What are polypeptides?


  Polypeptides contain three or more amino acids.
• What determines the structure of proteins?


  The structure of proteins is determined by the order and number of amino acids, types of bonding present, and shape of the protein.
• What is the primary structure of a protein?


  The primary structure is the order and number of amino acids in a protein.
• What is the secondary structure of a protein?


  The secondary structure is the shape that the amino acid chain takes, either alpha helix or beta pleated sheet.
• What is the tertiary structure of a protein?


  The tertiary structure is the 3D shape of the protein, which can be globular or fibrous.