Carbohydrates

• What are the three types of polysaccharides that a-glucose can form

  . amylopectin

  . amylose

  . glycogen
• Describe the differences in the structure of amylose and amylopectin

  . amylose has a linear chain of alpha glucose monomers

  . amylose has a straight helical structure

  . amylopectin is a highly branched chain of alpha glucose monomers

  . both amylopectin and amylose have 1-4 glycosidic bonds but amylopectin also has 1-6
• What are the 2 monosaccharides that join up to make sucrose?

  glucose + fructose
• What are the 2 monosaccharides that join up to make lactose

  glucose + galactose
• what are the 2 monosaccharides that join up to make maltose

  glucose + glucose
• What is a polysaccharide?

  A complex carbohydrate made up of multiple sugar molecules. 2 or more monosaccharides joined together by glycosidic bonds
• What is the name of the bond that forms between 2 monosaccharides

  glycosidic bonds
• describe the difference between alpha and beta glucose

  In alpha glucose, the -OH group attached to carbon 1 is below the plane of the ring whereas in beta glucose the -OH group attached to carbon 1 is above the plane of the ring.
• Why are glucose molecules polar and soluble in water?

  due to hydrogen bonds that form between hydroxyl groups and water molecules which allows glucose to be transported within cells and around the body easily.
• Define isomers


  molecules that have the same molecular formula but have a different arrangement of atoms/structure
• Give 2 examples of pentose monosaccharides

  ribose (RNA) and deoxyribose (DNA)
• What is the difference between ribose and deoxyribose

  ribose had one hydrogen atom and one -OH group attached to carbon 2 whereas deoxyribose has 2 Hydrogen atoms and no -OH group
• Via which reaction are glycosidic bonds formed

  a condensation reaction, involving the removal of H20
• What are polysaccharides mainly used as

  as an energy store and structural components of cells
• What are the 4 main polysaccharides

  Amylopectin, Amylose, Glycogen and cellulose
• Formation of 1-6 glycosidic bond between monosacharides creates a branching point
• What elements are carbohydrates made of


  carbon

  hydrogen

  oxygen
• Why do galactose, glucose and fructose have the same chemical formula but differ structurally and chemically?


  because of differing arrangements of atoms in the carbon chain
• What is starch?


  the major carbohydrate energy storage molecule in plants, usually as starch grains in plant cells
• What is starch composed of, give the percentage 


  Amylose makes up 20% of starch and amylopectin makes up 80%
• Is amylose or amyloppectin more soluble?


  amylose is less soluble in water than amylopectin
• What gives amylose a helical structure how is this helpful?


  angle of the 1-4 glycosidic bonds which makes amylose more compact- more glucose molecules can be stored in a smaller space
• What does the branching points on amylopectin allow?


  enzymes to attach so glucose can be released quickly
• Where is glycogen usually stored?


  as small insoluble granules particularly in muscles and liver
• Why can glycogen be broken down rapidly?

  due to the high number of alpha 1-6 glycosidic bonds that produce a highly branched structure and therefore more ends to release glucose which also indicates higher metabolic rate of animals compare with plants
• What does the branching point in glycogen mean?


  its more compact so more glucose molecules can be stored in a smaller space
• What does the branching point on amylopectin help for

  allows enzymes to attach so glucose can be released quickly
• How is cellulose formed?


  long straight chains made of beta glucose monomers joined by 1-4 glycosidic bonds, chains are straight as every alternate beta glucose molecule is flipped 180 degrees
• How are adjacent cellulose chains linked together to form what?


  linked together by hydrogen bonds to form strong fibres called microfibrils
• Function of the microfibrils in cellulose?

  insoluble and provide structural support to plant cells to prevent them from bursting in excess water. Have high tensile strength
• Give 3 difference in the structure of amylose and cellulose


  • amylose contains alpha glucose whilst cellulose has beta glucose
  • cellulose monomers alternate at 180 degrees and in amylose all moners have the same orientation
  • amylose has no hydrogen bonds between molecules but cellulose does