Question

Which enzyme causes conversion of prothrombin into thrombin? (a) Thrombinase (b) Prothrombinase (c) Thrombokinase (d) Rennin

Short answer

The enzyme that causes conversion of prothrombin into thrombin is Prothrombinase (b).

Step-by-step solution

Understanding the Concept of Prothrombin to Thrombin Conversion

The conversion of Prothrombin to Thrombin in human body is one of the final steps in clotting cascade. It is a common process within the coagulation pathway, which is vital for preventing blood loss on damage to the vascular system.

Identify the Correct Enzyme

In real biological terms, it's the enzyme called Prothrombinase which facilitates this conversion. Thrombinase is not a correct term used in biology, while Thrombokinase is known to initiate the clotting process but not directly linked to the conversion of Prothrombin into thrombin and Rennin is an enzyme related to digestion in mammals.

Key concepts

Prothrombin to Thrombin Conversion

The conversion of prothrombin to thrombin is a critical step in the coagulation process. This transformation is essential as it leads to the formation of fibrin, which is essential in clot formation. Prothrombin is a plasma protein synthesized in the liver and is present in an inactive form in the bloodstream. Upon activation, it is converted into thrombin, an active enzyme, which plays a central role in clot formation.

Prothrombin activation occurs at the site of injury, where tissue damage signals the body to form a blood clot to prevent excessive bleeding. During this process, prothrombin is cleaved by specific enzymes into thrombin.

This mechanism is crucial for hemostasis, which is the process that stops bleeding and involves the complex interaction of cellular and biochemical factors.

Prothrombinase

Prothrombinase is a complex enzyme system crucial for the conversion of prothrombin to thrombin, the essential step in forming a blood clot. This enzyme complex is composed of several components, including activated factor X (Xa), factor V, calcium ions, and negatively charged phospholipids.

When blood vessel damage occurs, prothrombinase is activated, triggering the conversion of prothrombin into thrombin. Thrombin then goes on to perform several vital functions, such as converting fibrinogen into fibrin, which solidifies the blood clot.

It is important to note that prothrombinase is the correct term in biological contexts. Expressions such as thrombinase are incorrect and not used in contemporary scientific nomenclature. Understanding the role of prothrombinase in the coagulation pathway sheds light on how our body prevents excessive blood loss and promotes healing.

Clotting Cascade

The clotting cascade is a series of enzymatic reactions that enable the coagulation of blood, effectively preventing excessive bleeding. It is often compared to dominoes falling in a sequence, with each enzyme activation prompting the next.

The cascade is split into the intrinsic and extrinsic pathways, both leading to the formation of the tenase complex, which activates factor X. Once activated, factor X interacts with factor V to form prothrombinase, leading to the conversion of prothrombin into thrombin.

Thrombin then plays a crucial role in converting fibrinogen into fibrin strands, which form the mesh that constitutes the structure of the blood clot. It also activates other clotting factors and platelets, amplifying the cascade.

This highly regulated cascade ensures that blood clots form only when necessary, helping to maintain normal circulation while providing an efficient means to stop bleeding. Understanding the clotting cascade is pivotal in comprehending how our body safeguards itself against blood loss.