L12: Phosphorus

Question 1

Where is most phosphorus found?

Answer 1

Bones (bound as mineral hydoxylapatite)

Question 2

Where is phosphorus used in the body?

Answer 2

Phospholipids
Protein activity (cell signaling)
In high energy molecules
Backbone of DNA & RNA

Question 3

Where is most organic phosphorus derived from?

Answer 3

Phosphoric acid

Question 4

What are the 4 different states of phosphoric acid?

Answer 4

Phosphoric acid
Dihydrogen phosphate
Hydrogen phosphate
Orthophosphate

Question 5

What is the Henderson-Hasselbach equation?

Answer 5

pH=pKa + log [A-] / [HA]

Question 6

What is the reaction called when the phosphodiester bond is hydrolysed?

Answer 6

SN2 (substitution nucleophilic 2 molecules)

Question 7

How does an anhydride form?

Answer 7

From condensation of 2 acid molecules

Question 8

Why is hydrolysis of the phosphoanhydride bond highly energetically favourable in ATP?

Answer 8

As it is highly exergonic (releases energy like exo)

Question 9

How is the free energy of hydrolysis explained?

Answer 9

By properties of reactants and products:
Electrostatic repulsion (-ive charge)
Resonance stabilisation (delocalised e-)
Solvation/hydration of products (dissolved more readily)