Carbohydrates

• Carbohydrates contain carbon, hydrogen, and oxygen
• Carbohydrates are called hydrated carbons
• What do carbohydrates contain?

  carbon, hydrogen, and oxygen
• Hydrated carbons means that for every carbon atom, there are two hydrogen and one oxygen atom
• The general formula for carbohydrates is CnH2nOn
• State three functions of carbohydrates:

  • store of energy
  • source of energy
  • structural units
• State the three main groups of carbohydrates:

  • monosaccharides
  • disaccharides
  • polysaccharides
• Monosaccarides are simple sugars and are the monomers of carbohydrates
• State the four main types of simple sugars:

  • triose
  • tetrose
  • pentose
  • hexose
• Triose and tetrose exist as straight chains
• Name two examples of hexose sugars:

  • glucose
  • galactose
• Name three pentose sugars:

  • ribose
  • deoxyribose
  • fructose
• In alpha-glucose, the OH group on C1 is below the plane of the ring
• In beta-glucose, the OH group on C1 is above the plane of the ring
• a-glucose + a-glucose -> maltose
• a-glucose + fructose -> sucrose
• B-glucose + B-glucose -> cellobiose
• B-galactose + a-glucose -> lactose
• Define Disaccharides:

  two monosaccharides joined together by condensation / glycosidic bond
• The bonds between monosaccharides are called glycosidic bonds
• Polysaccharides are the polymers of monosaccharides
• State the two types of polysaccharides:

  • heteropolysaccharides
  • homopolysaccharides
• Heteropolysaccharides contain more than one type of monosaccharide
• Homopolysaccharides only contain one type of monosaccharide
• Name two examples of heteropolysaccharides:

  • peptidoglycan
  • hyaluronic acid
• Name three examples of homopolysaccharides:

  • starch
  • cellulose
  • glycogen
• Starch stores energy in plants as starch grains
• Starch consists of amylopectin and amylose
• Enzyme amylase only breaks down alpha 1-4 glycosidic bonds into maltose
• Describe the structure of Amylopectin:

  • alpha 1-4 and 1-6 glycosidic bonds
  • highly branched - more open molecular structure with free ends, easier to break down ∴ good quick energy release
• Describe Amylose:

  • alpha 1-4 glycosidic bonds
  • linear chain - coils into a helix/spiral held in place by hydrogen bonds, chains can pack closely together ∴ good for structure
  • hydrogen bonds between oxygen at C2 and hydrogen at C3 of the next glucose molecule makes it compact and insoluble
• Cellulose is the most abundant in the plant cell wall
• Glycogen stores energy in animals as small granules in muscles and liver
• Describe Glycogen:

  • short alpha 1-4 glycosidic bonds- less able to coils
  • more alpha 1-6 glycosidic bonds - more compact
  • highly branched - more open molecular structure with free ends, easier to break down, ∴ good quick energy release
  • less dense and more soluble than starch ∴ broken down more rapidly to release glucose: glycogenolysis
• What type of galactose and glucose makes lactose?

  beta galactose and alpha glucose
• Benedict’s solution (also known as Benedict's reagent or the Benedict’s test) can be used as a test for reducing and non - reducing sugars
• All monosaccharides are reducing sugars
• Name the disaccharides that are reducing sugars:

  • lactose
  • maltose
  • cellobiose
• What is the name of the test used to test for reducing and non reducing sugars?

  Benedict's test
• Benedict's solution can be reduced by reducing sugars