Carbohydrates 3.1.2

• What is an anabolic and catabolic reaction?

  Anabolic=reaction involving adding molecules togetherCatabolic=reaction involving separating molecules
• Glucose, fructose and sucrose

  Glucose+fructose—>sucrose + H2OGlucose and fructose are isomers to each other (same formula, different structure)
• General formula for a monosaccharide

  Cn(H2O)n
• what bond are monosaccharides joined by?

  glycosidic bond (weak covalent bond)
• What are the two isomers of glucose?

  alpha glucose and beta glucose

  
• Different types of sugars

  
• 3 examples of disaccharides we need to know

  Maltose= alpha+alphaLactose=alpha+galactoseSucrose=alpha+fructose
• What are reducing sugars?

  A sugar that can donate an electron to a substance to reduce this substanceCan produce a colour change when oxidised or reduced
• What monosaccharides are reducing sugars?

  All
• What disaccharides are reducing sugars?

  
• how does benedict's test work?

  a reducing sugar will reduce the benedict's reagent changing the colour where as a non- reducing sugar will not result in a colour change, as it receives an electron Cu2+ + e- —> Cu2+
• Reducing sugar test


  -add 2cm of unknown sugar with an equal amount of Benedict’s solution-heat in a water bath for 5 mins (70-90°C)-observe results (blue-green-yellow-brick red) - semi quantitative resultsAlso produces a solid, insoluble precipitate
• Non-reducing sugar test


  -perform the reducing sugar test-if there is a negative result:-in a new test tube, add 2cm of unknown sugar-add dilute hydrochloric acid-heatThis causes any disaccharides to split into monosaccharides-add alkali as Benedicts needs alkali to work-add Benedict’s reagent and repeat Benedict’s test
• 3 polysaccharides and their two main functions

  Starch(plant storage of glucose)Glycogen(animal storage of glucose, muscles and liver)Cellulose(structural polysaccharide, strengthens cell wall)Functions:-energy store-structural role
• Starch:-found?-main role?-made of?-structure?-two types?

  -found in:plants cells in the form of small granules/grains-main role:energy storage in plants-made of:alpha glucose monomers-structure:coiled and branched (due to the presence of 1-4 and 1-6 glycosidic bonds)-two types: amylose (coiled, 1-4), amylopectin (coiled and branched, 1-4 and 1-6)
• Starch (structure related to function)

  Helical so compactInsoluble so does not affect water potentialBranched so glucose is easily released for respirationLarge molecule so cannot leave cell/cross cell membrane
• Test for starch

  -add iodine in potassium iodide to test solution-shake or stir-if starch is present, solution will change from yellow/orange to blue/black
• Glycogen:-found?-made of?-similar to?-main role?-structure?-soluble or insoluble?

  -found: in animal cells (small granules mainly in muscle or liver)-made of: alpha glucose monomers-very similar to:amylopectin but there is less 1-4 bonds and more 1-6 bonds)-main role:energy storage in animals-structure:coiled and branched-insoluble and large
• Glycogen (structure related to function)


  -coiled so compact-polymer of glucose so easily hydrolysed and provides respiratory substrate for energy release-branched so more ends for hydrolysis-insoluble so does not affect water potential
• Cellulose structure


  -long, straight chains of beta glucose-joined by hydrogen bonding-to form micro/macrofibrils-provides rigidity and strength