translocation

• photosynthesis in chloroplasts creates sucrose
• High concentration of sucrose in site of production
• sucrose diffuses down concentration gradient into companion cells via facilitated diffusion
• active transport of H+ ions from companion cells into spaces in cell wall using energy
• creates concentration gradient, H+ moves down concentration gradient via carrier proteins into sieve tube elements
• co transport of sucrose with H+ via protein co-transporters to transport sucrose into sieve tubes
• H+ attaches to co-transport protein back to companion cells, sucrose attaches to carrier protein into sieve tube elements
• Sieve tube element has no nucleus or organelles, only cytoplasm and mitochondria
• Monomers are smaller units which can create larger molecules and the polymers are made from lots of monomers which are bonded together
• Monomers

  • glucose
  • amino acids
  • nucleotides
• Polymers

  • starch
  • cellulose
  • glycogen
  • proteins
  • DNA
  • RNA
• Condensation reaction to create polymers


  1. Joining two molecules together

  2. Creating a chemical bond

  3. Removing water
• Hydrolysis reaction to break apart monomers


  1. Breaking a chemical bond between two molecules

  2. Involving the use of water
• Carbohydrate monosaccharides

  • glucose
  • fructose
  • galactose
• Carbohydrate disaccharides

  • sucrose
  • maltose
  • lactose
• Carbohydrate polysaccharides

  • starch
  • cellulose
  • glycogen
• Alpha glucose

  Hydrogen atom on top, hydroxyl group on bottom of carbon 1
• Beta glucose

  Hydroxyl group on top, hydrogen atom on bottom of carbon 1
• Glycosidic bond


  Chemical bond that forms between two monosaccharides in disaccharides and polysaccharides
• Starch


  • Glucose store in plants
  • Alpha glucose monomers
• Cellulose


  • Structural strength in plant cell walls
  • Beta glucose monomers
  • One-to-four glycosidic bonds
• Glycogen


  • Glucose store in animals
  • Alpha glucose monomers
  • One-to-four and one-to-six glycosidic bonds
• Triglycerides


  Lipid with three fatty acid chains attached to a glycerol molecule
• Phospholipids


  Lipid with two fatty acid chains and a phosphate group attached to a glycerol molecule
• Saturated fatty acid


  No double bonds between carbon atoms, fully saturated with hydrogen
• Unsaturated fatty acid


  At least one double bond between carbon atoms
• Triglycerides


  • High ratio of energy-storing carbon-hydrogen bonds
  • Can act as metabolic water source
  • Do not affect water potential
• Phospholipids


  • Hydrophilic head, hydrophobic tails
  • Form a bilayer in water
• Amino acid


  Central carbon, hydrogen, amine group, carboxyl group, variable R group
• Forming a dipeptide


  Condensation reaction to remove water and form a peptide bond
• Forming a polypeptide


  Multiple condensation reactions to form peptide bonds
• Primary protein structure


  Order or sequence of amino acids in a polypeptide chain
• Secondary protein structure


  Folding or twisting of the polypeptide chain, held by hydrogen bonds
• Tertiary protein structure


  Further folding to create a unique 3D shape, held by ionic, hydrogen and disulfide bonds
• Quaternary protein structure


  Protein made up of more than one polypeptide chain
• Enzyme


  Protein in the tertiary structure that catalyzes reactions by lowering activation energy
• Enzymes


  • Specific to one reaction due to unique active site shape
  • Induced fit model - active site changes shape to fit substrate
• Factors affecting enzyme-controlled reaction rate


  • Temperature
  • pH
  • Substrate concentration
  • Enzyme concentration
  • Inhibitors
• Competitive inhibitor


  Binds to the enzyme's active site
• Non-competitive inhibitor


  Binds to a different part of the enzyme