Carbohydrates

• what are the isomers of glucose?


  alpha glucose and beta glucose

  
• how are polysaccharides formed?


  By the condensation reaction of many glucose units
• glycogen and starch are formed by


  condensation of alpha glucose
• cellulose is formed by

  condensation reaction of beta glucose
• what are isomers


  molecules that have the same number of each atom but the atoms are arranged differently
• maltose


  formed by two glucose molecules by an alpha 1-4 glycosidic bond

  
• sucrose


  formed from glucose and fructose joined by an alpha 1-2 bond

  
• lactose


  formed from galactose (its B - galactose) and glucose joined by a B1-4 glycosidic bond

  
• amylose


  two glucose units connected by an alpha 1-4 glycosidic bond forms maltose

  
• amylopectin


  same structure as glycogen, just fewer branches and found in plants

  
• glycogen


  multiple glucose units connected by an alpha 1-4 glycosidic bond forms maltose

  
• why is glycogen a good storage molecule?


  It is a polymer of alpha glucose.

  It forms long chains with many branches which allows glucose to be released quickly (by hydrolosis) from the end of each branch. It has short chains of 10-15 before it folds.

  Its compact, so stores lots of glucose in a small space.

  Its insoluble so it does not affect the water potential of the cell.
• Why can't humans digest cellulose?


  Humans lack the enzyme necessary to break down cellulose, making it an insoluble fiber in our diet.
• What makes cellulose chains stronger than glucose chains in amylose?


  B1-4 glycocidic bonds
• How do cellulose molecules differ from amylose molecules in terms of structure?


  Cellulose molecules are straight and do not coil.
• How does hydrogen bonding contribute to the properties of cellulose?


  Hydrogen forms between cellulose molecules and between the sugar units within the molecules to create a tight mesh.
• What property of cellulose allows it to resist osmotic pressure?


  Its rigid structure
• Disaccharide properties


  Made of 2 monosaccharides

  Joined together by a glycosidic bond

  Via a condensation reaction
• Starch's bond between monomers


  1-4 glycosidic bonds in amylase

  1-4 and 1-6 in amylopectin
• What is the function of starch?


  Store of glucose
• Where is starch located?


  plant cells e.g. chloroplasts
• What is the structure of starch?


  Made of 2 polymers:

  Amylose - an unbranched helix

  Amylopectin - a branched molecule
• How is the structure of starch related to its function?


  Helix can compact to fit a lot of glucose in a small space.

  Branched structure increases surface area for rapid hydrolysis back to glucose.

  Insoluble so wont affect water potential.
• What is cellulose's bond between monomers?


  1-4 glycosidic bonds
• What is cellulose's function?


  Structure strength for cell wall
• What is cellulose?


  Cellulose is a complex carbohydrate and the most abundant organic polymer on Earth.
• What is the primary component of plant cell walls?

  Cellulose is the primary component of plant cell walls.
• What type of carbohydrate is cellulose classified as?


  Cellulose is classified as a polysaccharide.
• What are the building blocks of cellulose?


  Cellulose is made up of long chains of glucose molecules.
• What is the molecular structure of cellulose?


  • Composed of beta-glucose units
  • Linked by beta-1,4-glycosidic bonds
  • Forms long, straight chains
  • Each glucose unit is rotated 180° relative to its neighbors
• What type of bond connects the glucose units in cellulose?


  Beta-1,4-glycosidic bonds connect the glucose units in cellulose.
• How do cellulose molecules arrange themselves?


  • Form microfibrils by aligning parallel to each other
  • Create crystalline regions that are tightly packed
  • Form amorphous regions that are less ordered
  • Bundle into larger fibrils
  • Arrange in layers with different orientations in cell walls
• What is the correct order of cellulose organization from smallest to largest?


  Cellulose chains → Microfibrils → Fibrils → Cell wall layers
• What are microfibrils in the context of cellulose structure?


  Microfibrils are composed of multiple cellulose chains aligned parallel to each other.
• What role does hydrogen bonding play in cellulose structure?


  • Forms intramolecular bonds within a single cellulose chain
  • Forms intermolecular bonds between adjacent cellulose chains
  • Creates strong, rigid crystalline regions
  • Contributes to cellulose's strength and insolubility in water
• How does hydrogen bonding contribute to the strength of cellulose fibers?


  It creates a strong network within and between cellulose chains.
• How does cellulose's structure relate to its function in plants?


  • Provides structural support and mechanical strength
  • Maintains cell wall integrity and shape
  • Resists water loss due to hydrogen bonding
  • Allows for flexibility through crystalline and amorphous regions
  • Influences direction of cell growth
• What adaptation might a plant in a windy environment have regarding cellulose?


  An increased proportion of cellulose in the cell walls for enhanced strength and flexibility.
• Which structural feature of cellulose contributes most to a plant's ability to resist water loss?


  Extensive hydrogen bonding contributes to water resistance.
• Why does extensive hydrogen bonding in cellulose help plants resist water loss?


  It makes cellulose insoluble in water, maintaining structural integrity and preventing water loss.