Carbs

• Monosaccharides (simple sugars) –

  are carbohydrates with relatively small molecules.

  They are soluble in water.
• glucose is C6 H12 06
• Glucose is a type of sugar known as a hexose, (made of six carbon atoms.)

  It has aa folded, cyclic form, called a pyranose ring,

  (made of five carbon atoms and one oxygen atom.)
• The glucose molecule exists in 2 forms

  ALPHA FORM (-H atom was trapped up)

  BETA FORM (-H atom trapped down)
• FRUCTOSE is a hexose sugar found in cells.

  It has a ring structure that-different from glucose.

  Fructose forms into a ring with four carbon atoms and an oxygen atom,

  called a furanose ring.
• Disaccharides – are carbohydrates made of two monosaccharides

  (monomers) combined together.

  For example, sucrose is formed when a molecule of alpha-glucose combines with a molecule of fructose.
• When monosaccharides combine

  in a condensation reaction,

  the bond formed is called a glycosidic bond – a strong covalent

  bond.

  In the reverse process, disaccharides can be digested into 10

  monosaccharides by a hydrolysis reaction. This reaction involves adding a molecule of water (hydro) and splitting (lysis) the glycosidic bond.
• Maltose is another common disaccharide formed by joining an

  alpha-glucose molecule to a glucose molecule and is a product of starch digestion.
• Polysaccharides – are built from many monosaccharides linked by glycosidic bonds.

  Thousands of monosaccharide units make up a

  polysaccharide.
• Some polysaccharides function as stores of energy, glycogen and

  starch
• Chitin is sugar found in crunchy insects- cockroach
• Starch – is a mixture of two polysaccharides, both of which are polymers of alpha glucose.

  
  

  20-30% amylose

  70-80% amylopectin.
• IN STARCH-

  The amylose is an unbranched chain (1,4 links only),

  amylopectin has branches at points (1,4 and 1,6 links).

  bonds between glucose in starch bring the molecules together-forma helix forms.

  Starch is the major storage carbohydrate of plants. laid down as compact grains in leucoplasts. This is because animals cant make starch.
• Starch is useful energy source in animals because-

  molecules compact and insoluble (WATERPROOF)

  readily hydrolysed to form sugar (many terminal glucose molecules)
• amylose-

  structure bends so more space for 6 bonds- not as tightly packed together
• Glycogen – is a polymer of alpha glucose.

  similar to

  amylopectin, although the glycogen molecule is more highly branched.


  this is because animal storage sugar need to release more energy as they move
• cellulose is a structural sugar
• Cellulose have 1,4 - links.

  these links between beta glucose molecules make them

  straight, unbranched cellulose chains.

  Successive beta glucose molecules are rotated 180 in the molecules.
• Each cellulose molecule forms many hydrogen bonds with the surrounding cellulose molecules,

  forming an extremely strong structure –

  insoluble, tough, durable and slightly elastic.

  ~(characteristics)

  
  

  In cell walls,

  the cellulose fibre are laid down in layers running in

  different directions, adding further strength to the walls.
• In cell walls the cellulose fibre are laid down in layers running in

  different directions, adding further strength to the walls.