How catabolic and anabolic pathways are connected.

[Becki182]

Hi all,

 

Im revising for my upcoming end of year exams and the 20 mark questions are stumping me...not sure what else to include.

 

The question I am currently answering is 'Using suitable examples explain how anabolic and catabolic pathways connected within metabolism'.

 

I understand what the questions means and I have given roughly 12 points worth but unsure what else I can add, therefore my question is can anyone indicate what I have missed please.

 

 

The points I have made so far are the definitions of both catabolic and anabolic, which uses energy or produces it and in what forms, an example of both types of pathway. I have also mentioned amphibolic pathways and an example of that. I have summarised the importance of amphibolic pathways and given examples of how anabolic and catabolic work together (example of fatty acids entering TCA from anabolic reaction. The other example being glycolysis producing pyruvate needed for the start of TCA), then again summarised the importance of these working together. I would guess this is around 12 distinct points but the marking guide is looking for 20 marks.

 

 

Thanks

[BabcockHall]

I am not sure what you mean by "example of fatty acids entering TCA from anabolic reaction." Fatty acids do not enter the TCA cycle from an anabolic reaction; they enter after beta-oxidation, which is catabolic. Do you think that the question wishes you to discuss the joint regulation of anabolic and catabolic pathways?

[Becki182]

I am not sure what you mean by "example of fatty acids entering TCA from anabolic reaction." Fatty acids do not enter the TCA cycle from an anabolic reaction; they enter after beta-oxidation, which is catabolic. Do you think that the question wishes you to discuss the joint regulation of anabolic and catabolic pathways?

Apologies, that's what I get for typing like I think rather than typing for others to understand; was a mistake.

 

Yes, thats what it is asking but I was just looking for more ways in which this happens as I am not sure how I could pick up the extra marks since more examples of intermediates wont give me any more marks.

[BabcockHall]

There are many examples of how hormones (and also certain intracellular signals) regulate oppositely directed enzymes in a reciprocal manner. The most obvious examples are phosphofructokinase-1 and fructose 1,6-bisphosphatase and how fatty acid biosynthesis is regulated at its first committed step in eukarotic organisms. The paired enzymes of glycogen anabolism and catabolism are also well-studied.

Edited November 20, 2015 by BabcockHall

[Xalatan]

Yeah you are probably being asked to describe the relationship between glycolysis, private dehydrogenase, tca, gluconeogenesis, beta oxidation and lipid synthesis. Most metabolites feed into pyruvate, acetyl coa and various intermediates of the tca so as long as you know your way around you should be able to describe anabolic and catabolic pathways. Don't forget cholesterol and ketone bodies come from acetyl coa too.

Also glycogen metabolism and the pentose phosphate pathway branch off g6p, and you should describe oxidatve phoshorylation. there's enough for 20 points if you break down the different pathways systematically. You can probably even go into purine synthesis, breakdown and salvage from ppp, as well as the urea cycle and haem synthesis from the tca for extra marks.