Lecture 13 - Biology and Minerals

Question 1

How does chirality impact chemistry?

Answer 1

Chirality refers to handedness, and molecule chirality influences face growth. Some can be more favourable e.g. D-aspartic acid more favoured than L

Question 2

How can morphology be changed abiotically?

Answer 2

1. Control growth rate
2. Control diffusion rate
3. Additive to change surface reactivity
4. Use metastability - stop a reaction at specific phase

Question 3

What is the most stable supersaturated carbonate in seawater?

Answer 3

Dolomite then calcite then aragonite

Question 4

How does biology manipulate chemistry?

Answer 4

1. Makes a global problem a local problem - localises reactions to controlled environment and concentrates resources. (e.g. stops mineral growth in the body)
2. Changes playing field (chemical environment) - to promote or inhibit growth (e.g. limits Ca and Ph uptake)
3. Delineating space in which minerals can grow - system forced to choose best mineral for its purpose (metastable state) (e.g. collagen)

Question 5

What is important for controlling the solubility of biological apatite?

Answer 5

Lattice substitutions

Question 6

How can ion activity be changed (solubility product)?

Answer 6

Ion pumping, complexion pair formation, speciation, change pH or remove water (increases ion activity). When solubility product is less than the activity product precipitation will occur.

Question 7

How can mineralisation be changed by using additives?

Answer 7

Inhibitor molecules can change time needed for nucleation and stabilise one phase over another
E.g. Mg can cause aragonite to form over calcite (higher surface energy)