Biological molecules Flashcards
Condensation Reaction
Reaction where 2 molecules combine to form a single molecule.
Water is produced as it removed in the process
Hydrolysis
Reaction that breaks down large, biological molecules. The reaction requires water.
Formation of molecules
Covalent bonding
Ionic bonding (weaker than covalent)
Hydrogen bonding
Polar molecule
A molecule with an uneven distribution of charge
Polymers and monomers
monomers are molecules that can be linked together to form long chains.
These long chains of monomer sub-units are called polymers and the process by which they are formed is therefore called polymerisation.
Metabolism
All the chemical processes that take place in living organisms
Molar solution
contains 1 mole of solute in each litre of solution
Monomer of carbohydrates
A single monomer is therefore called a monosaccharide.
(di, poly)
general formula for monosaccharides
(CH2O)n
Test for reducing sugars
Benedict’s test:
Add 2cm3 of food sample [grind]
equal amount of water
Gently heat in boiling water for 5 mins
If positive - blue to brick red.
Maltose
Glucose + glucose
Sucrose
Glucose + Fructose
Lasctose
Glucose + Galactose
Bond between 2 monosaccharides
Glycosidic Bond - formed by a condensation reaction between the hydroxyl group.
[OH-H]O, this gives out the h2o.
Breaking Glycosidic bonds
Adding water / hydrolysis
Test for Non Reducing Sugars
Hydrolyse the disaccharide into its monosaccharide from, eg sucrose - glucose + fructose.
Conduct the test for reducing sugars
NO colour change:
Add another food sample into equal volume of HCl in a test tube - heat gently for 5 mins
HCl hydrolysis the non reducing sugar
Add HCO3 (hydrogen carbonate) - neutralises the HCL.
pH test to see if alkaline. [Benedict’s reagent doesn’t work in acidic conditions]
Conduct benedict’s test again
+ve = blue - orange / red
Test for starch
Iodine Test
Sample in test tube / spotting tile
Add iodine drops
+ve test = orange - blue/black
Qualities of polysaccharides that make them suitable for storage.
Large
Insoluble
Starch
Only found in plants
Made of α glucose molecules linked by glycosidic bonds formed by condensation reactions.
May be Branched or Unbranched
= forms tight coils ∴ compact
Main role of starch, glycogen and cellulose
Starch - storage
Cellulose - arrangement and strength
Glycogen - storage (animals)
How is starch suitable for storage ?
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Insoluble
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