Metabolism

[deleted647690]

I think I've posted about this before, but I partially audited a bchm course this summer because the intro biochem course I took never covered metabolic pathways. So I figured I'd learn it this summer along with mcat studying. At the end of the course, I realized it was a huge waste of time because it was extremely detailed, and I was half assing it and didn't benefit. I sort of tried to teach myself and study along the way, but I didn't really keep up well enough. I had to postpone my mcat date, which was supposed to be in september, so now I'm studying during the semester. I still feel like I never adequately learned metabolism stuff. I finally finished the berkeley review chapter on metabolism after taking like 2 weeks to read it and watching khan academy videos along the way. Now I'm failing the practice questions. I don't really know what to do. Metabolism seems really overwhelming; there are so many interrelationships between all of the different intermediates and sites of action in the body, I just don't know what to focus on.

Should I just keep rereading the chapter and watching the khan academy videos until it sticks?

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[aldol16]

Exactly what metabolic pathways are you focusing on? You should know that the MCAT tests mainly on reasoning skills so if it tests on an obscure pathway, the pathway itself might be diagrammed in front of you in the passage. They're not interested in whether you recall all the intermediates and feedback loops. Now, that doesn't mean you shouldn't know the central metabolic pathways of life inside out (glycolysis, TCA cycle, oxidative phosphorylation) but you should get the main idea from the pathways (e.g. urea cycle serves to get rid of excess nitrogen in the body).

 

[deleted647690]

Exactly what metabolic pathways are you focusing on? You should know that the MCAT tests mainly on reasoning skills so if it tests on an obscure pathway, the pathway itself might be diagrammed in front of you in the passage. They're not interested in whether you recall all the intermediates and feedback loops. Now, that doesn't mean you shouldn't know the central metabolic pathways of life inside out (glycolysis, TCA cycle, oxidative phosphorylation) but you should get the main idea from the pathways (e.g. urea cycle serves to get rid of excess nitrogen in the body).

What would be the main ideas? I'm basically trying to understand glycolysis,gluconeogenesis, kreb's, ETC, oxidative phosphorylation, pentose phosphate pathway, fatty acid synthesis, fatty acid oxidation, and urea cycle.
I'm trying to understand how the cycles relate to eachother, and I believe that requires knowing intermediates. I'm trying to understand the overall reactions for each.
Also, I'd like to learn how each is regulated, and that seems like it is basically just the law of mass action applied. However, that again requires knowing many of the reactants and products.

I just feel misguided because I never learned this in a formal classroom setting, and I always feel like I am missing something.

 

[FMDoge2020]

-What goes in, what comes out.
-Rate determine steps,
-general function of each process.
-General interconnection of them.
Like Aldo said, nothing too complicated or detailed.

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[theonlytycrane]

draw out the pathways over and over

 

[eteshoe]

Reading about deregulated metabolic pathways in cancers helped me understand their normal fxns. YMMV.

 

[deleted647690]

Is the enzyme in the first step of the Kreb's cycle called citrate synthase or citrate synthetase? And would that be a lyase or a ligase?
BR says that it is synthetase and is a lyase, but sources online say it is synthase, a ligase (https://www.reddit.com/r/Mcat/comments/4ic03q/should_we_memorize_steps_of_metabolism_pathways/) (post by Grand_sales, right near top of the comments)


And I found another source online that switches the two names by saying that a lyase is a synthase, and a ligase is a synthetase (so that switches what both BR and online source said
http://www4.uwsp.edu/chemistry/tzamis/365f00pdfs/enzymeclasses02.pdf




And thanks. I'm just going to review all the pathways again, draw it on a whiteboard, and take a picture of it so I can look at that every time I forget

 

[alpha-GTP]

Reviewing all the pathways would be great, but I would focus on glycolysis, both forms of fermentation, krebs, ETC/OP, and beta oxidation (not so much this one). They are the most high yield and likely ones to show up in passages. The rest will either be 1 or 2 free standing questions at most or a passage where you are basically given all the relevant info on the pathway.

 

[dark_knight]

Is the enzyme in the first step of the Kreb's cycle called citrate synthase or citrate synthetase? And would that be a lyase or a ligase?
BR says that it is synthetase and is a lyase, but sources online say it is synthase, a ligase (https://www.reddit.com/r/Mcat/comments/4ic03q/should_we_memorize_steps_of_metabolism_pathways/) (post by Grand_sales, right near top of the comments)


And I found another source online that switches the two names by saying that a lyase is a synthase, and a ligase is a synthetase (so that switches what both BR and online source said
http://www4.uwsp.edu/chemistry/tzamis/365f00pdfs/enzymeclasses02.pdf




And thanks. I'm just going to review all the pathways again, draw it on a whiteboard, and take a picture of it so I can look at that every time I forget

Doesn't really matter.

I think you're focusing too much on the details like the posters before me stated. You're only expected to know a basic understanding of all the pathways.

I would focus on these details.

-What goes in, what comes out.
-Rate determine steps,
-general function of each process.
-General interconnection of them.
Like Aldo said, nothing too complicated or detailed.

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