Module: Biological Molecules (Core Concepts)
Q: What are the 4 main inorganic ions?
1. Magnesium or Mg2+ = constituent of chlorophyll
2. Iron or Fe2+ = constituent of haemoglobin
3. Phosphate ions (PO43-) = used to make nucleotides and found within cell membrane.
4. Calcium ions (Ca2+) = structural component of bones and teeth, as well as cell walls.
Q: State the 8 main properties of water:
1. Metabolite, in hydrolyses and condensation reactions.
2. High specific heat
3. High latent heat of vaporisation.
4. Cohesion / High surface tension
5. Transparent
6. Solvent
7. High surface tension
8. High density which provides buoyancy, as water is denser than air. Also, ice is less
dense than water.
Q; What is the general name given to a molecule with 3, 5 and 6 carbons in its structure?
3 = triose
5 = pentose
6 = hexose
Q: Describe the difference between alpha and beta glucose:
They differ based on the position of OH group on carbon 1.
Alpha glucose has the OH on the bottom of the carbon 1, whereas beta glucose has
the OH group on top.
Q: Draw alpha and beta glucose:
Q: Describe some general functions of monosaccharides?
1. A source of energy in respiration. C-C and C-H bonds are broken to release energy,
which is transferred to bind an inorganic phosphate to ADP to form ATP.
2. Building blocks for larger molecules.
3. Intermediates in reactions.
4. Constituents of nucleotides, e.g. ribose and deoxyribose.
Q: State three monosaccharides:
Glucose
Fructose
, Galactose
Q: What is the general formula of a monosaccharide?
(CH2O)n
Q: What two monosaccharides make up the disaccharide maltose?
Glucose + Glucose
Q: What two monosaccharides make up sucrose?
Glucose + Fructose
Q: What two monosaccharides make up lactose?
Glucose + Galactose
Q: How do you test for reducing sugars?
Carry out the Benedict’s test.
Mix equal volumes of benedict’s reagent and the solution being tested and heat to at
least 70°C.
If a reducing sugar is present, such as glucose, the solution will turn from blue
through green, yellow and orange and finally a brick-red precipitate.
Q: How could you test for a non-reducing sugar?
Some disaccharides, such as sucrose, are non-reducing and give a negative result.
How to test for this is by heating the non-reducing sugar in the presence of
hydrochloric acid, which breaks the molecule into its constituent molecules.
Benedict’s reagent works in alkaline conditions, so an alkali is added, such as sodium
carbonate.
Then test for reducing sugars, and a brick-red precipitate formed.
Q: Describe the structure and function of starch:
Stores energy in plants.
Starch is produced by repeat units of alpha-glucose.
Starch is a mixture of two polysaccharides, Amylopectin and Amylose:
1. Amylose = unbranched chain of glucose molecules joined by 1,4 glycosidic bonds, as
a result of that amylose is coiled and thus very compact.
2. Amylopectin = made up of glucose molecules joined by 1-4, and 1-6, glycosidic
bonds, due to the presence of the many side branched, it makes the chain very
branched and compact. It is rapidly digested by enzymes.,
Q: Describe the structure and function of Glycogen:
Main energy storage in animals and is formed from many molecules of alpha glucose
joined together by 1-4, and 1-6, glycosidic bonds.
It has a large number of side branches with a very similar shape to amylopectin.
Relatively large, but compact molecule which means it can store large amounts of
energy.
