Biology/Citric Acid Cycle
Advertisement
Question
Hi, I am a 2nd year student at university and studying for a Biochemistry exam. I was curious to know why the Citric acid cycle is called the citric acid cycle because it doesn't appear to have anything to do with citric acid. If you could answer this, it would be great thanks!
Thanks for using AllExperts. The citric acid cycle--also known as the Krebs cycle or tricarboxylic acid cycle--does involve the compound citric acid, although in the body it is usually found in a slightly different form with a slightly different name. You may have seen diagrams of the CAC use the term "citrate" instead of "citric acid"; this is fairly common, and it reflects the fact that, in the body, citric acid loses its hydrogen ions to form its conjugate base, which is citrate. Citric acid itself is not found in the body--only citrate is, because that is the stable form of the molecule within the body. Citrate is the conjugate base of citric acid.
The TCA cycle includes citrate in the following steps:
Oxaloacetate+Acetyl CoA-->Citrate (catalyzed by citrate synthase)
followed by
Citrate-->Isocitrate (catalyzed by aconitase)
Compare the two structures seen here:
Citric acid: http://en.wikipedia.org/wiki/File:Zitronens%C3%A4ure_-_Citric_acid.svg
Citrate: http://en.wikipedia.org/wiki/File:Citrate-2D-skeletal.png
- Add to this Answer
- Ask a Question
| Rating(1-10) | Knowledgeability = 10 | Clarity of Response = 10 | Politeness = 10 |
| Comment | Awesome! Thanks heaps! | ||
Related Articles
Answers by Expert:
John Locke
Expertise
I will answer all biology-related questions through the undergraduate level. I will explain unclear concepts and suggest approaches to solving problems, but would prefer not to completely solve homework problems for you. If you are completely stumped on homework, tell me what you already know and I will help you as much as possible. Please do not ask me for ideas on school research projects; part of research is determining a suitable area of investigation, and that's not a task that should be completed by someone else. Please don't simply send me your homework for solutions. If you are having difficulty after you have started an analysis, I will be happy to direct your thinking; in particular, I would prefer to not simply solve pedigrees for students, but I will be happy to assist in solving pedigrees that you have already started. If you don't understand how to analyze a pedigree, I'd highly recommend watching this video, in which a biology professor explains the basic concepts of pedigree analysis: http://www.youtube.com/watch?v=HbIHjsn5cHo
Experience
I have a BS in Bioengineering with a concentration in Chemical Engineering (which included a heavy focus on biology), and have taught biology, biochemistry, and related subjects for some time now.
Education/Credentials
BS Bioengineering, Penn State University
MCAT/DAT/OAT Instructor
©2012 About.com, a part of The New York Times Company. All rights reserved.