The Zwitterion and Isoelectric Point

Question 1

What is zwitterion?

Answer 1

1)A zwitterion is an amino acid that has both positive and negative charges

2)A zwitterion has an overall net charge of 0

Question 2

What is an Isoelectric point?

Answer 2

For every amino acid, there exist a pH where both the positive and negative charges are present (i.e. the amino acid has overall zero charge)

Question 3

Properties of Isoelectric point

Answer 3

1)The charge an amino acid carries is determined by the pH of the solution the amino acid is in

2)The isoelectric point is the pH at which the zwitterion exists (i.e. the amino acid has overall zero charge)

3)Different amino acids usually have different isoelectric points

Question 4

What happens when pH is below the isoelectric point? (ie. more acidic environment)

Answer 4

1)In acidic environment, there is a high concentration of hydrogen protons

2)All the functional groups on the amino acid gets protonated

3)Therefore at pH below the isoeectric point, the amino acid bomes positively charged

Question 5

What happens when pH is above the isoelectric point? (i.e. more basic environment)

Answer 5

1)In an alkalin (basic) environment, there is a low concentration of hydrogen (+) protons (or high in hydroxide, OH (-) )

2)All the functional grous n the amino acid gets deprotonated

3)Therefore, at pH above the isoelectric point the amino acid becomes negatively charged