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Biochemistry Basics – 14774

Neelam Maurya

Question

Homocysteine, an amino acid is present at high levels in Roshan’s blood tests as suspected by his vascular surgeon. He had presented with peripheral vascular disease.
Assertion: An increase of homocysteine in serum elevates the risk of coronary artery disease

Reason: Homocysteine interacts with the lysyl residue of collagen interfering with collagen cross-linking. It forms homocysteine thiolactone. These particles aggregate and are endocytosed by macrophages and increase the tendency of atherogenesis.

A. Both Assertion and Reason are true, and Reason is the correct explanation for Assertion

B. Both Assertion and Reason are true, and Reason is not the correct explanation for Assertion

C. The assertion is true, but reason is false

D. The assertion is false, but reason is true

 

Show Answer

Correct Answer » A

Explanation

Ans.A
An increase of 5 micromol/L of homocysteine in serum elevates the risk of coronary artery disease by as much as a cholesterol increase of 20 mg/dl.
Homocysteine interacts with the lysyl residue of collagen interfering with collagen cross-linking.
It forms homocysteine thiolactone, a highly reactive free radical which thiolates LDL particles.
These particles aggregate and are endocytosed by macrophages and increase the tendency of atherogenesis.

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