Globular proteins

How many subunits are present in hemoglobin?

• 2

• 4

• 3

How are the amino acids arranged in hemoglobin?

• Only non-polar amino acids are found at the interior of the protein.

• non-polar amino acids are found at the exterior while polar amino acids are present inside the protein.

• Two histidines that are polar amino acids are found at the interior of the protein.

• Both non-polar and polar amino acids are present on the protein surface

What is meant by cooperativity?

• Hemoglobin cooperatively remove CO₂ from blood while delivers oxygen.

• Cooperativity in hemoglobin is a result of Bohr effect.

• CO₂ decreases the affinity of hemoglobin for O_2.

• The binding of O₂ to one subunit increases the affinity of the remaining 3 subunits for oxygen.

Which are the allosteric effectors of hemoglobin?

• CO₂

  O₂

  H⁺

  2,3 BPG

• CO₂

  H⁺

  2,3 BPG

• CO₂

  O₂

  H⁺

• CO₂

  O₂

  2,3 BPG

Which alternative describe the Bohrs effect?

• More oxygen is released in presence of H⁺ and CO₂

• The oxygen dissociation curve shifts to the right when pH is increased.

• The oxygen dissociation curve shifts to the right when partial pressure of CO₂ is decreased.

Which protein has high affinity for oxygen?

• Myoglobin

• Hemoglobin

Which state of hemoglobin is stabilized after binding protons?

• Taut state

• Relaxed state