Biochemistry Protein Structure and Function 2

Question 1

What is the isoelectric point (pI) of a protein?

Accepted Answer

The pH at which the protein carries no net charge

Answer

The isoelectric point is the pH at which the net charge of the protein is zero, meaning positive and negative charges are balanced.

Question 2

Chaperone proteins assist in which process?

Accepted Answer

Correct protein folding

Answer

Molecular chaperones bind to unfolded or misfolded proteins and provide a protected environment that facilitates correct folding, preventing aggregation.

Question 3

Which prosthetic group is found in myoglobin and hemoglobin, enabling oxygen binding?

Accepted Answer

Heme group

Answer

The heme group contains an iron atom (Fe²⁺) coordinated within a porphyrin ring, which reversibly binds molecular oxygen.

Question 4

The cooperative binding of oxygen to hemoglobin is best described by which model?

Accepted Answer

Concerted (MWC) model

Answer

The concerted (Monod-Wyman-Changeux) model proposes that all subunits switch simultaneously between T (tense, low affinity) and R (relaxed, high affinity) states.

Question 5

2,3-Bisphosphoglycerate (2,3-BPG) affects hemoglobin oxygen binding by:

Accepted Answer

Decreasing oxygen affinity by stabilizing the T state

Answer

2,3-BPG binds in the central cavity of deoxyhemoglobin and stabilizes the low-affinity T state, promoting oxygen release to tissues.

Biochemistry Practice Test

Biochemistry Practice Test

Biochemistry Protein Structure and Function 2