Topic 1

• What are monomers?

  Smaller, repeating molecules that form polymers

  
• What are polymers?

  Molecules made from many similar monomer molecules
• What occurs during a condensation reaction?

  • Two molecules join together
  • Forming a chemical bond
  • Releasing a water molecule

  
• What occurs during a hydrolysis reaction?

  • Two molecules separated
  • Breaking a chemical bond
  • Using a water molecule
• What is formed when two monomers join together?

  A dimer
• What molecule is released during a condensation reaction?

  Water
• What kind of molecules are lipids?

  Lipids are not polymers
• If two molecules with the chemical formula $C_6H_{12}O_6$ combine in a condensation reaction, what is the resulting chemical formula?


  $C_{12}H_{22}O_{11}$
• What are monosaccharides?

  Monomers from which larger carbohydrates are made
• What is the difference between isomers?

  Same molecular formula but differently arranged atoms
• Where is the OH group located in alpha-glucose?

  Below carbon 1
• Where is the OH group located in beta-glucose?

  Above carbon 1
• What is a disaccharide?

  Two monosaccharides joined together
• How are disaccharides formed?

  Condensation reaction with glycosidic bond and releasing water
• Which monosaccharides form maltose?

  Glucose + glucose

  
• Which monosaccharides form sucrose?

  Glucose + fructose
• What type of bond joins monosaccharides?

  Glycosidic bond
• Which monosaccharides form lactose?

  Glucose + galactose
• What are polysaccharides?

  Many monosaccharides joined together with glycosidic bonds
• How are polysaccharides formed?

  Many condensation reactions, releasing many water molecules
• What is the basic function and structure of starch?

  Function: Energy store in plant cells

  Structure:

  • Polysaccharide of α-glucose
  • Some has 1,4-glycosidic bonds (amylose)
  • Some has 1,4- and 1,6-glycosidic bonds (amylopectin)

  
• What is the basic function and structure of glycogen?

  Function: Energy store in animal cells

  Structure:

  • Polysaccharide of α-glucose
  • 1,4- and 1,6-glycosidic bonds → branched
• What glycosidic bonds are present in amylose?

  1,4-glycosidic bonds

  
• What glycosidic bonds are present in amylopectin?

  1,4- and 1,6-glycosidic bonds

  
• Why is amylose helical?

  For compact storage in cell
• Why can't starch leave the cell?

  Large, insoluble polysaccharide molecule
• Why does starch not affect the water potential of the cell?

  Insoluble in water
• Why is glycogen branched?

  Compact and more ends for faster hydrolysis
• Why does glycogen have more ends?

  For faster hydrolysis
• Why is glucose needed from glycogen?

  For respiration to make ATP
• What is the basic function and structure of cellulose?

  Function: Provides strength and structural support to plant / algal cell walls

  Structure:

  • Polysaccharide of β-glucose
  • 1,4-glycosidic bonds → straight, unbranched chains
  • Chains linked in parallel by hydrogen bonds, forming microfibrils

  
• What type of glucose is cellulose made from?

  β-glucose
• Why is every other β-glucose molecule inverted in cellulose?

  To form long, straight, unbranched chains
• Why are hydrogen bonds important in cellulose?

  Link parallel strands to form microfibrils

  
• Why does cellulose provide strength to plant cell walls?

  Many hydrogen bonds linking parallel strands

  
• How do you test for reducing sugars?

  Reducing sugars = monosaccharides, maltose, lactose

  1. Add Benedict’s solution (blue) to sample
  2. Heat in a boiling water bath
  3. Positive result = green / yellow / orange / red precipitate
• How do you test for non-reducing sugars?

  Non-reducing sugars = sucrose

  1. Do Benedict’s test and stays blue / negative
  2. Heat with acid (hydrolyse into reducing sugars)
  3. Neutralise with alkali
  4. Heat with Benedict’s solution
  5. Positive result = green / yellow / orange / red precipitate
• What should you use to neutralise a solution after adding acid?

  Alkali (eg. sodium bicarbonate)
• What is the next step after carrying out Benedict's test to measure the quantity of sugar in a solution?

  Filter and dry precipitate
• How can a colorimeter be used to measure the quantity of sugar in a solution?

  Measure absorbance of known concentrations to plot calibration curve