B3 - Biological Molecules Flashcards
Maltose
Glucose + glucose
Sucrose
Glucose + Fructose
Lactos
Glucose + galactose
Glycosidic bond
Formed between two glucose molecules.
Condensation reaction
A reaction where water is formed as one of the products.
Alpha-glucose
Hydrogen above hydroxide on right side
Beta-glucose
Hydroxide above hydrogen on right side
General formula for monosaccharides
C(n)H(2n)O(n)
Monosaccharides
A single sugar unit
Disaccharide
When two monosaccharides link together.
Polysaccharide
When 2 or more monosaccharides link together.
Glycogen
Is the main storage carbohydrate in animal cells.
In mammals it is found mainly in liver and muscle cells.
Glycogen is also a polymer of alpha glucose with a branching structure similar to amylopectin.
Cellulose
Is a polymer of b glucose joined together by (1-4) glycosidic bonds.
In order to form these bonds alternate b glucose molecules are rotated 180 degrees
Starch
Is composed of long chains of alpha glucose molecules
In plant cells it is used as an energy storage molecule. Grains of starch can be observed in chloroplasts.
It is hydrolysed by amylases produced at various points along the humane gut during digestion to release maltose and glucose
Starch is not found in animal cells.
Lipids
Lipids include fats, oils and cholesterol - all composed of C, H and O
Oils are liquid at room temperature and if cooled solidify into fats.
Lipids are non-polar and are hydrophobic - insoluble in water
They are not miscible and tend to remain in droplets or globules.
Triglycerides
Fats and oils are called triglycerides
A triglyceride is composed of one molecule of glycerol joined via ester bonds to 3 molecules of fatty acid this is called esterification (an example of a condensation reaction)
Ester bonds
An alcohol group reacting with an acidic group produces an ester bonds
The triglyceride has 3 ester bonds connecting each of the -CH2 fatty acid chains
Hydrolysis breaks ester bonds and reverses the condensation reaction. This reaction occurs in the guy to allow transport across the gut membrane and into the blood.
Ester bonds equation
Triglyceride + H20 reacts with acid and lapse to form glycerol + fatty acids
Saturated fats
In saturated fats each C bonds to 4 other atoms
All the bonds between neighbouring carbon atoms are single bonds.
No more hydrogen atoms can be added
Fats are solid at room temperature and tend to contain saturated fats.
Unsaturated fats
Unsaturated fats have fewer hydrogen atoms than they might
There are one or more double bonds between carbon atoms.
A polyunsaturated chain has many unsaturated carbon atoms
Oils are liquid at room temperature and tend to contain unsaturated fats.
Phospholipids
Phospholipids are found in cell and organelle membranes.
In phospholipids one of the fatty acids is substituted by a phosphate molecule attached to choline
Cholesterol
Cholesterol is a large multi-ringed, hydrophobic structure.
Hydrophobicity allows it to fit between the fatty acid chains of the phospholipids. This is crucial to its role as a regulator of membrane fluid.
Cholesterol regulates the fluidity of the membranes by…
Blocking large lateral motions of the fatty acids
Preventing the lipids crystallising by fitting between them
ATP
Adenosine triphosphate
Is a small molecules
Water soluble
Energy is released as phosphate groups are removed
It comes from changes in chemical potential energy in the system (anhydride bonds are hydrolysed)
ADP and ATP are phosphorylated nucleotides.
Structure of ATP
2 adenine
One ribose
3 phosphate groups
ATP reactions
ATP + H20 = ADP + Pi (+30.6kJ mol^-1)
ADP + H20 = AMP + pi (+30.6kJ mol^-1)
AMP + H20 = Adenosine + Pi (+13.8kJ mol^-1)
ATP is broken down into…
ADP and inorganic phosphate, releasing the energy contained within the bond. ATPase catalyses this process. The energy is then used for ‘work’
Starch test
Use iodine to produce a dark blue-black colour from a yellow-brown colour. Works with starch dissolved in water or just by placing iodine directly on it.
Protein test
Biuret solution contains sodium hydroxide and copper sulphate. It will go from blue to a violet colour. Intensity of colour gives a rough indication of the amount of protein.
Lipids test
Ethanol test. If lipids present a white emulsion will be present on top of the mixture