2.1.2

• why is water polar

  oxygen is more electronegative than hydrogen meaning the bonding electrons are shared unequally giving oxygen a slight negative charge and hydrogen and slight positive charge
• polarity of water allows it to

  form hydrogen bonds between other oppositely charged molecules
• why is a hydrogen bond drawn dotted?

  the bond is weak so it is constantly breaking and reforming
• Hydrogen bonding diagram

  A) -

  B) -

  C) +

  D) +

  
• functions of water

  solvent

  reaction medium

  transport medium

  capillary action

  coolant

  habitat

  ice
• water as a solvent

  dissolves polar molecules as opposite charges attract pulling apart the molecule
• water as a reaction medium


  allows molecules to move and react
• water as a transport medium

  blood , tissue fluid

  xylem , phloem

  cytoplasm
• water in capillary action

  cohesion - water molecules stick together

  adhesion - water molecules stick to the surface of a vessel
• water as a coolant

  high SHC and LHofV mean a lot of energy is required for water to evaporate so it removes heat , sweating
• water as a habitat

  requires extreme temperatures to change so stable , allows gametes and nutrients to circulate as they are less dense so float , aquatic organisms , insects , prokaryotes
• water as ice

  less dense in ice form so floats on water creating habitat and insulates against extreme cold
• Glucose formula


  C6H12O6
• What does a hexose monosaccharide contain


  1 unit containing 6 carbons
• Alpha glucose

  A) H

  B) OH

  C) H

  D) OH

  E) OH

  F) H

  G) H

  H) HO

  I) CH2OH

  J) H

  K) C

  L) C

  M) C

  N) C

  O) C

  P) O

  
• Beta glucose

  A) OH

  B) H

  C) H

  D) OH

  E) OH

  F) H

  G) H

  H) HO

  I) CH2OH

  J) H

  K) C

  L) C

  M) C

  N) C

  O) C

  P) O

  
• Difference between alpha and beta glucose


  The OH group on C1 is below on alpha and above on beta
• How does a glycosidic bond form


  Condensation reaction forming one molecule of water
• How is a glycosidic bond broken?


  Hydrolysis reaction using one molecule of water
• What types of glycosidic bonds are there?


  1-4 and 1-6

  
• What type of chains do 1-4 glycosidic bonds form

  straight
• What type of chains do 1-6 glycosidic bonds form


  Branched
• Is glucose soluble


  Yes as it has many OH groups that can form hydrogen bonds
• Why is glucose used for energy


  The carbon - carbon and carbon - hydrogen bonds contain a lot of energy
• where is starch used


  plants
• What is starch made from


  amylose and amylopectin
• Amylose


  Alpha glucose joined with 1-4 glycosidic bonds.

  A straight, coiled chain making it compact

  
• Amylopectin


  Alpha glucose joined by 1-4 and 1-6 glycosidic bonds.

  Coiled chain with side branches

  
• Properties of starch


  Insoluble - stops water entering cells causing swelling

  Compact - stores well
• Properties of amylopectin


  Fast breakdown - side branches
• Glycosidic bond

  A) H

  B) OH

  C) O

  D) H20

  
• Where is glycogen used


  Animals
• Glycogen structure


  1-4 and many 1-6 glycosidic bonds joining alpha glucose molecules

  Branched for quick energy release but still compact for storage. Stable.
• Where is cellulose used


  Plants
• Cellulose structure


  Long unbranched chain of beta glucose

  The chains are joined by hydrogen bonds forming microfibrils

  
• cellulose function

  Structural support
• What does pentose monosaccharide mean?


  1 unit containing 5 carbons
• within carbohydrates for every 1 carbon there are


  2 hydrogens and 1 oxygen
• disaccharides contain how many units


  2
• ribose vs deoxyribose

  A) OH

  B) H