Unit 2

• What are the three elements that make up carbohydrates?

  Carbon, hydrogen, and oxygen
• What is the main function of carbohydrates in living organisms?

  To provide energy
• What are the classes of carbohydrates?

  • Monosaccharides
  • Disaccharides
  • Polysaccharides
• What are monosaccharides?


  Simple sugars that are the basic units of carbohydrates
• How do we test for glucose?

  With Benedict's solution or Fehling's A and B solutions
• What happens to Benedict's solution when glucose is present and heated?

  It turns red-brown
• What are disaccharides?


  Double sugars formed by two monosaccharides
• What is the scientific name for double sugars?

  Disaccharides
• What are polysaccharides?


  Large carbohydrate molecules made of many monosaccharides
• What is the function of starches in organisms?

  To store energy
• How are starches broken down in organisms?

  They are broken down to glucose for energy
• Where is starch stored in plant cells?

  In the chloroplasts
• What is glycogen?


  A form of starch found in animal cells
• What is cellulose and where is it found?

  It is the main component of plant cell walls
• Why can't humans digest cellulose?

  Because the glucose molecules are joined differently than in starch
• What is the test for starch?

  It turns iodine solution blue-black
• What is the disaccharide found in milk?

  Lactose
• What is the disaccharide found in sugar cane?

  Sucrose
• What are lipids?


  Fats and oils
• What elements do lipids contain?

  Carbon, hydrogen, and oxygen
• What are phospholipids?


  Lipids that also contain phosphorus
• How do we test for lipids?

  With organic solvents such as ether
• What is the importance of lipids?

  They store energy and make up cell structures
• What is the structure of lipid molecules?

  Made of three fatty acids joined to glycerol
• What determines whether a lipid is solid or liquid?

  How the fatty acids are joined to glycerol
• What are saturated fatty acids?

  Fats that are solid at room temperature
• What are unsaturated fatty acids?

  Fats that are liquid at room temperature
• Why are unsaturated fats considered healthier?

  They are linked to lower cholesterol levels
• What are proteins made of?

  Long chains of amino acids
• What elements do proteins contain that differentiate them from carbohydrates and lipids?

  Nitrogen
• What tests are used to detect proteins?

  Millon's reagent or the Biuret test
• What is the importance of proteins in living organisms?

  They are crucial for cell structure and function
• What percentage of the dry mass of most cells is made up of proteins?

  More than 50%
• What are some functions of proteins?

  Carrying oxygen, forming antibodies, and regulating body functions
• What are enzymes?


  Proteins that act as catalysts in chemical reactions
• How do enzymes function?

  They speed up chemical reactions without being changed
• What is the lock-and-key model?

  A hypothesis explaining how enzymes and substrates fit together
• What happens to enzymes at high temperatures?

  They can become denatured and lose their function
• What is pH?


  A measure of how acidic or alkaline a solution is
• What is the optimum pH for enzymes?

  The best pH at which an enzyme functions