What plasma protein is converted into a fibrin mesh during clot formation?

• A. Fibrin
• B. Albumin
• C. Fibrinogen
• D. Globulin

Answer: (C)

In clot formation the substance that is converted into the fibrin mesh is fibrinogen. Thrombin acts on fibrinogen to remove specific peptides, turning it into fibrin monomers that then polymerize and cross-link to form the insoluble fibrin mesh that stabilizes the clot. Albumin and globulins are other plasma proteins with roles in transport, osmotic balance, and immunity, but they are not substrates for forming the fibrin mesh. Fibrin itself is the product that results from this conversion, not the starting material.