lipids carbs and proteins

• Name the bond formed between glycerol and fatty acids

  Ester bond
• State the type of reaction involved in the breakdown of the monoglyceride


  hydrolysis
• What are the two ‘building blocks‘ of triglycerides 


  Glycerol and 3 fatty acids
• Why are triglycerides not considered to be polymers 


  because the units are not identical
• State 2 functions of triglycerides in mammals 


  Insulation - prevent heat loss

  Electrical insulation - myelin sheath

  Protection - delicate organs
• What bond forms between 2 alpha glucose molecules

  Glycosidic bond
• What is the test for a reducing sugar 


  Add Benedict’s reagent and heat - positive result is a colour change from blue to brick red
• Explain the colour change in the reducing sugars test

  The Cu2+ ions in the benedicts reagent gain 1 electron from the reducing sugar making it Cu+ which is a red precipitate
• Describe the test for a non reducing sugar

  Add 2 drops of HCl to the test solution

  Boil

  Add sodium hydroxide (alkali) and Benedict’s reagent

  Heat

  Observe colour change
• Explain the non reducing sugars test 


  The addition of the acid hydrolyses the glycosidic bond in the non reducing sugar, this makes it into a reducing sugar which then undergoes the same test as a normal reducing sugar
• What is the test for lipids 


  Add ethanol to the test solution

  Shake

  Add this solution to cold water

  Positive result is a white emulsion formed
• What are the physical properties of cellulose 


  Straight

  Unbranched

  Alternating beta glucose
• What are the physical properties of starch 


  Coiled

  Branched

  Made of alpha glucose
• What are the physical properties of glycogen 


  Coiled

  Highly branched

  Made of alpha glucose
• alpha glucose + alpha glucose = ?


  maltose
• alpha glucose + galactose = ?


  lactose
• alpha glucose + fructose =? 


  sucrose
• What bonds form between 2 or more molecules of water?

  Hydrogen bonds because water is a dipole (partially charged ends)
• Water is cohesive - what does that mean?


  The molecules stuck to eachother - forming things like water droplets
• What does surface tension mean


  Where water meets air the bonds between the water molecules are stronger
• Why is surface tension useful 


  It provides habitats for insects such as pond skaters
• Water has a high specific heat capacity - why is this useful 


  Provides a thermostable environment for chemical reactions and living things
• Water is a metabolite - what does that mean? 


  It is produced in condensation reactions and needed in hydrolysis reactions
• Solid water is less dense than liquid water - why is this important? 


  The ice stays on top and insulates the water underneath preventing it from freezing all the way down. This means that aquatic organisms can live there.
• Water has a high latent heat of vaporisation - why is this important 


  It takes a lot of energy for it to change state, this means that it removes a lot of heat from the body when we sweat
• Water is transparent - why is this important

  This means that aquatic photosynthetic organisms can survive under the water
• What are isomers 


  Molecules that have the same chemical formula but a different arrangement of atoms
• What are the 2 main groups of lipids 


  Triglycerides

  Phospholipids
• The two main good groups for lipids are oils and fats - which tend to be saturated and which unsaturated 


  Oils - unsaturated (liquid)

  Fats - saturated (solid)
• What is a COOH group called?


  A carboxyl group
• What is the charge on a phosphate ion in a phospholipid?


  negative (-1)
• Phospholipids are hydrophilic and hydrophobic - which end is which? 


  The phosphate group end is hydrophilic and the glycerol and fatty acid end is hydrophobic
• In a cell membrane how do phospholipids arrange themselves 


  The hydrophilic phosphate ‘head’ facing outward and the glycerol/fatty acid end facing inward
• What are the three ‘groups‘ within an amino acid?

  Amino group

  R group

  Carboxyl group
• What test do you do to test for protein

  Add biurets reagent (blue) to the test solution, if a protein is present a colour change from blue to purple will be observed
• Name the bond formed by 2 amino acids joining together

  Peptide bond
• What is a polymer of amino acids called

  Polypeptide
• What is the meaning of ‘hydroxylating‘ 


  Adding a hydroxide group
• Which 2 substances are formed when 2 amino acids bond together

  Dipeptide and water
• What is the definition of a monomer 


  Smaller units from which larger molecules are made