Prothrombin is

Prothrombin is

• A. A plasma protein; converted to thrombin in the clotting process
• B. A white blood cell involved in immunity
• C. A platelet-derived growth factor
• D. A type of antibody

Answer: (A)

Prothrombin is a plasma protein that acts as a zymogen in the coagulation cascade. It’s produced by the liver and circulates in the blood in an inactive form. When the clotting pathway reaches the common phase, prothrombin is converted into thrombin by the prothrombinase complex. Thrombin then transforms soluble fibrinogen into insoluble fibrin, forming the clot, and it also helps amplify the process by activating other clotting factors and platelets. So the key idea is that prothrombin is the inactive precursor that becomes thrombin to drive clot formation. It is not a white blood cell, a platelet-derived growth factor, or an antibody.

Prothrombin is a plasma protein that acts as a zymogen in the coagulation cascade. It’s produced by the liver and circulates in the blood in an inactive form. When the clotting pathway reaches the common phase, prothrombin is converted into thrombin by the prothrombinase complex. Thrombin then transforms soluble fibrinogen into insoluble fibrin, forming the clot, and it also helps amplify the process by activating other clotting factors and platelets. So the key idea is that prothrombin is the inactive precursor that becomes thrombin to drive clot formation. It is not a white blood cell, a platelet-derived growth factor, or an antibody.