Biochem Ex 1 - Hydrophilic, Buffer

Question 1

Is cocaine a vasoconstrictor?

Answer 1

Yes

Question 2

Is cocaine polar or non-polar?

Answer 2

polar

Question 3

What happens to cocaine in an acid environment?

Answer 3

In an acid environment where there are more hydrogens present, hydrogen gets pushed into the cocaine molecule (gets protonated) giving it the acid form to the right

Question 4

Are basic molecules polar or non-polar?

Answer 4

non-polar

Question 5

How does cocaine get inside the body?

Answer 5

Cocaine has to pass the lipid barrier (found on membranes) to get into the blood. In its polar form, it cannot get through the barrier so it gets converted to the non-polar form, which can then pass to the blood. It does so with the hydrophobic effect. But the acid form (protonated form) is the one that can carry out the actions we want, so it has to be converted again once inside the body.

Question 6

Why do lipid molecules come together in water?

Answer 6

There is less surface area wet so there is more random water around the molecule (more entropy). Nature loves randomness (entropy), so this is a more favored state (the hydrophobic molecule being close together). So likes-like-like.

Question 7

How does pH affect absorption?

Answer 7

Acidic drug: If in an acidic medium the acid will withdraw protons from the acidic drug and cause it to unionize so it will go through the membrane better

Basic drug: If in an acidic medium the acid will add protons to the basic drug making it ionized and more difficult to absorb

Question 8

What is the Henderson-Hasselbalch equation?

Answer 8

ph = pKa + log( [conj base] / [acid] )

Question 9

What is pKa?

Answer 9

pKa is equal to the pH at which the two forms are equal.

Question 10

Calculate the pKa:

Answer 10

-1/2

Question 11

Draw a titration curve for the below:

Answer 11

Question 12

What is the most important buffer system in the body and blood?

Answer 12

Bicarbonate buffer system

Question 13

What is the second most important buffer system in the body?

Answer 13

Protein buffer system

Question 14

Where is the protein buffer system more important and where is it less important?

Answer 14

More important intracellularly since there are more proteins in cells. Less important extracellularly.

Question 15

Which is the least important buffer system in the body?

Answer 15

Phosphate buffer system. DNA, nucleotides carry phosphate and buffer as well. Less important

Question 16

What pH the compartment of the body is in affects the hydrophobicity of the drug.

Something with _____ pKa can hang on to the hydrogen at a lower pH.

a) low
b) high

Answer 16

low