Question

The oxygen dissociation curve for myoglobin is
A. Sigmoidal
B. Hyperbolic
C. Linear
D. Parabolic

Answer 1

Hint: The shape of the oxygen dissociation curve of Hb is hyperbolic. Myoglobin is an iron and oxygen-binding protein found in the skeletal muscle tissue of vertebrates.

Complete answer:
Option A Sigmoidal: Sigmoidal is the S-shaped part of the hindgut and is the last region of the large bowel before the rectum. It begins in front of the pelvic brim as a continuation of the descending colon. The oxygen dissociation hemoglobin curve is a sigmoidal curve. The curve plots the proportion of hemoglobin in the saturated form on the vertical axis. The oxygen dissociation curve for myoglobin is not Sigmoidal because there is a difference between the oxygen dissociation curve for myoglobin and for hemoglobin. Hence the dissociation curve for myoglobin will not have a sigmoidal shape. This is because the affinity of myoglobin for oxygen is greater than that of the hemoglobin so this is the reason why the oxygen dissociation curve for myoglobin is not a sigmoidal curve.
Option A is wrong

Option B Hyperbolic: Each molecule of myoglobin can bind $$O_2$$ inside the muscle fiber. As a result of the concentration of $$O_2$$ in the surrounding fluids, the $$O_2$$-Mb bond is reversible. Hence as more $$O_2$$ is forced into the vital blood as result myoglobin becomes increasingly saturated. The oxygen dissociation curve for myoglobin is the hyperbolic dissociation curve indicates that a much lower concentration of $$O_2$$ is needed to saturate the myoglobin molecules.

Option B is correct

Option C Linear: The oxygen dissociation curve for myoglobin is a hyperbolic curve because the oxygen dissociation curve for myoglobin is the hyperbolic dissociation curve indicates that a much lower concentration of $$O_2$$ is needed to saturate the myoglobin molecules. Hence the oxygen dissociation curve for myoglobin is not linear.


Myoglobin is an iron- and oxygen-binding protein binding found in the skeletal muscles of the vertebrates. Myoglobin and hemoglobin are distantly related to each other. Myoglobin has more oxygen affinity compared to hemoglobin.
Option C is wrong

Option D Parabolic: The oxygen dissociation curve for myoglobin is not in a parabolic shape. Because myoglobin oxygen dissociation curve is in hyperbolic shape due to the oxygen concentration inside the muscle fibers.


Myoglobin is made up of a single polypeptide. Myoglobin will hold its oxygen supply until the muscles are low. A high concentration of muscle cells allows the organism to hold its breath for a longer period. Myoglobin is the first protein to have three-dimensional structure revealed.
Option D is wrong

Hence, the correct answer is option B

Note:
Myoglobin is an iron and oxygen-binding protein in the muscles. A high concentration of myoglobin in muscle cells allows organisms to breathe. Myoglobin is distantly related to hemoglobin. Diving mammals such as whales and seals have muscles particularly with high myoglobin. Myoglobin is the first protein to have its three-dimensional structure. A high concentration of myoglobin in muscle cells allows organisms to hold their breath.