Biology Question on Aspirin Watch

nwmyname
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Hi,
this was the question that I found in the biology textbook and I wanted to see if I was right.

Aspirin has been used to reduce level and inflammation for over 100 years. Scientists have recently discovered that aspirin prevents cells from producing prostaglandins by inhibiting cyclooxygenase (Cox-1), one of the enzymes in the metabolic pathway involved ln prostaglandins synthesis (prostaglandins are ‘eicosanolds (Their molecules contain 20 carbon atoms) and act as local hormones They were at first thought to origlnate in the prostate gland and, although scientists now know this is not true, the name has been kept).

Aspirin adds a chemical group (acetyl) permanently to one of the monomers in the enzymes active site.

Thromboxanes are also eicosanoids. The enzyme thromboxane synthase catalyses their synthesis, within platelets. Thromboxanes promote blood clotting.

Aspirin also inhibits the production of thromboxanes. Platelets have no DNA and cannot synthesise more enzymes.

Some people take a low daily dose of aspirin to reduce their
risk of heart attack or stroke.



The questions are:
(a) What are the monomers that make up are active site of the cyclooxygenase? [1]

(b) Suggest which enzyme in the metabolic pathway shown above is inhibited by aspirin. Explain the reasons for your cholce. [3]

(c) Explain how aspirin inhibits the formation of product molecules from substrate molecules. [4]

(d) Explain why platelets cannot synthesise more enzymes [2]

(e) Suggest why people continue to take a low daily dose of aspirin to reduce are risk of blood clotting even though their platelets cannot make enzymes to replace those permanently inhibited by aspirin [2]

I can do the rest but I am really stuck about question B.
What is the main reason. I thought enzyme A but I'm unsure.
Thanks.
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RDB1826
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I'm thinking Enzyme A as well for question (b). The reasons are that both the production of thromboxane and prostaglandins need to be stopped by aspirin, so we need to inhibit the production of substance Z (which is common to both the production of thromboxane and prostaglandins). Inhibition of enzyme B will not stop the production of thromboxane. Inhibition of enzyme C will not stop the production of prostaglandins.
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John Newman
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Hi, do you have time to tell me the answers to these questions, found a exam paper with similar questions wanted to check if they're the same thank you
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John Newman
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(Original post by RDB1826)
I'm thinking Enzyme A as well for question (b). The reasons are that both the production of thromboxane and prostaglandins need to be stopped by aspirin, so we need to inhibit the production of substance Z (which is common to both the production of thromboxane and prostaglandins). Inhibition of enzyme B will not stop the production of thromboxane. Inhibition of enzyme C will not stop the production of prostaglandins.
hi do you knows the answers A-E Can you help me out?
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