Lecture 2 (8/17) -Biochemical Principles 1 Flashcards
At 25 degrees C, in 1L of water …
1 x 10^-7 hydronium and hydroxy ions form
pH=
pH= -log10[H+]
The equilibrium constant is
Ka=[H+][A-]/[HA]
You can not add strait H to a solution to make it more acidic, it will just bubble. You could add what though?
Add a protonated base
HH equation
pH= pKa +log ([A-]/[HA])
Assume 0.1 eq of base has been added to a fully protonated solution of acetic acid. What is the value of pH relative to the pKA?
pH is less than the pKa because there are 0.9 eq of fully protonated, so means it is more acidic therefore pH is less than pKa.
If 0.5 eq of base is added to a solution of the fully protonated acetic acid then what?
pH equals pKa
If pH of 0.9 eq of base is added to a solution of the fully protonated acid , then ..
pH is greater than pKa because there is more deprotonated form so that pH will be higher
Buffers can be used reliably within one pH unit of their
pKa
A molecule with a pKa of 6.04 in a pH of 7.2
The molecule will lose the proton in general. But.. the proton will not always be lost due to surrounding envirnments of proteins.
Do cells want good buffers?
The cell wants to able to sense change. A Good buffer can keep a cell from being able to sense certain changes. Highly buffered systems can cause such a change to take more time to reverse.
Bicarb buffer pKa
6.1
Phosphate buffer pKa
7.2
Is blood pH in the range of the bicarb buffer system?
No!! Blood pH is 7.3 ish, so it is out of bicarb buffer maximum end of 7.1
Describe Bohr Effect
Lungs pH=7.6 high affinity for O2 low for CO2
As vessels progress through periphery, it becomes low affinity for O2 and high affinity for CO2.
