Carbohydrates and Lipids

• Carbohydrates


  Large group of organic compounds occurring in foods and living tissues and including sugars, starch, and cellulose
• Lipids


  Fats, oils, waxes, and related compounds
• Carbon atom


  • Can form up to four single bonds or a combination of single and double bonds with other carbon atoms or atoms of other non-metallic elements
  • Allows for the formation of diverse compounds upon which life is based
• Production of macromolecules


  1. Condensation reactions link monomers to form a polymer

  2. Digestion of polymers into monomers by hydrolysis reactions
• Monomers


  Molecules which join to other similar molecules to form polymers
• Polymers


  Macromolecules built out of monomers
• Macromolecules


  • Polysaccharides
  • Polypeptides
  • Nucleic Acids
  • Triglycerides
  • Phospholipids
• Condensation reaction


  Combines two molecules, releasing a water molecule
• Hydrolysis reaction


  Addition of a water molecule to break down a large molecule
• Monosaccharides


  Carbohydrates that cannot be broken down into smaller carbohydrates by hydrolysis
• Monosaccharides


  • Glucose, ribose, fructose
• Pentose sugars


  Monosaccharides that contain 5 carbons
• Hexose sugars


  Monosaccharides that contain 6 carbons
• Alpha-glucose


  Glucose isomer with the -OH on carbon 1 pointing down
• Beta-glucose


  Glucose isomer with the -OH on carbon 1 pointing up
• Glucose


  • Soluble in water
  • Transportable in body fluids
  • Chemically stable
  • Primary fuel for respiration, yielding up to 36 ATP
• Polysaccharides


  Composed of many sugar molecules combined through condensation reactions
• Starch and glycogen


  • Serve as energy storage compounds in plants and animals respectively
  • Composed of long chains of glucose molecules that can be added or removed by condensation and hydrolysis reactions
  • Compact due to coiling and branching
• Amylose


  Long chains of alpha-glucose molecules in starch
• Amylopectin


  Long chains of alpha-glucose with branching chains of alpha-glucose in starch
• Glycogen


  • Branched polymer of glucose molecules
  • Forms a highly compact, coiled structure in cells
  • Linear chains linked by alpha-1,4-glycosidic bonds, with branching through alpha-1,6-glycosidic bonds
  • Allows for efficient storage and mobilization of glucose for energy
• Cellulose


  Unbranched polysaccharide composed of beta-glucose molecules found in plant cell walls
• Cellulose microfibrils


  • Groups of cellulose molecules held together by hydrogen bonds
  • Have high tensile strength, allowing them to maintain the structural integrity of plant cell walls
• Cellulose molecules consist of long chains of beta-glucose molecules bonded between carbon-1 and carbon-4, with every second beta-glucose molecule flipped, resulting in straight chains
• Cellulose


  An unbranched polysaccharide composed of beta glucose molecules which is found in the cell wall of plants
• Structure of cellulose


  • Alternating orientation of beta-glucose monomers, giving straight chains that can be grouped in bundles and cross-linked with hydrogen bonds
• Cellulose microfibrils


  Cellulose molecules form groups, known as microfibrils, held together by hydrogen bonds
• Cellulose microfibrils


  • Have high tensile strength, allowing them to maintain the structural integrity of the cell walls of plants
• Glycoproteins


  Integral proteins located within phospholipid bilayers of cells, have a chain of carbohydrates attached
• Glycoproteins


  • The carbohydrate has a specific shape and can act as an antigen
• Cell-to-cell recognition


  The glycoprotein on the surface of one cell is recognized by receptors on the surface of another
• ABO Antigens


  Antigens are substances which stimulate an immune response and the production of antibodies. Red blood cells have glycoproteins on their plasma membranes that distinguish ABO blood type
• ABO Blood Groups


  • Blood Type A
  • Blood Type B
  • Blood Type AB
  • Blood Type O
• Lipids


  Substances in living organisms that dissolve in non-polar solvents but are only sparingly soluble in aqueous solvents, including fats, oils, waxes and steroids
• Phospholipids


  Composed of one glycerol molecule attached to two fatty acids and one phosphate
• Triglyceride Formation


  Triglycerides are formed by three condensation reactions between glycerol and three fatty acids, releasing three water molecules
• Saturated fatty acids


  Have a straight, linear shape due to the absence of double bonds between carbon atoms, allowing them to pack tightly together and form a solid at room temperature
• Unsaturated fatty acids


  Have one or more double bonds, introducing kinks or bends in the fatty acid chain, preventing them from packing closely together and resulting in a liquid state at room temperature
• Monounsaturated fatty acids


  Have one double bond between carbon atoms in the hydrocarbon chain
• Polyunsaturated fatty acids


  Have two or more double bonds between carbons in the hydrocarbon chain