A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

In what stage of cellular respiration is most of the carbon dioxide produced? A. glycolysis B. fermentation C. citric-acid cycle D. electron transport chain

  • This Question is Closed
  1. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Respiration occurs in three stages. The first stage is glycolysis, which is a series of enzyme-controlled reactions that degrades glucose (a 6-carbon molecule) to pyruvate (a 3-carbon molecule) which is further oxidized to acetylcoenzyme A (acetyl CoA). Amino acids and fatty acids may also be oxidized to acetyl CoA as well as glucose. In the second stage, acetyl CoA enters the citric acid (Krebs) cycle, where it is degraded to yield energy-rich hydrogen atoms which reduce the oxidized form of the coenzyme nicotinamide adenine dinucleotide (NAD+) to NADH, and reduce the coenzyme flavin adenine dinucleotide (FAD) to FADH2. (Reduction is the addition of electrons to a molecule, or the gain of hydrogen atoms, while oxidation is the loss of electrons or the addition of oxygen to a molecule.) Also in the second stage of cellular respiration, the carbon atoms of the intermediate metabolic products in the Krebs cycle are converted to carbon dioxide. The third stage of cellular respiration occurs when the energy-rich hydrogen atoms are separated into protons [H+] and energy-rich electrons in the electron transport chain. At the beginning of the electron transport chain, the energy-rich hydrogen on NADH is removed from NADH, producing the oxidized coenzyme, NAD+ and a proton (H+) and two electrons (e-). The electrons are transferred along a chain of more than 15 different electron carrier molecules (known as the electron transport chain). These proteins are grouped into three large respiratory enzyme complexes, each of which contains proteins that span the mitochondrial membrane, securing the complexes into the inner membrane. Furthermore, each complex in the chain has a greater affinity for electrons than the complex before it. This increasing affinity drives the electrons down the chain until they are transferred all the way to the end where they meet the oxygen molecule, which has the greatest affinity of all for the electrons. The oxygen thus becomes reduced to H2O in the presence of hydrogen ions (protons), which were originally obtained from nutrient molecules through the process of oxidation. During electron transport, much of the energy represented by the electrons is conserved during a process called oxidative phosphorylation. This process uses the energy of the electrons to phosphorylate (add a phosphate group) adenosine diphosphate (ADP), to form the energy-rich molecule ATP.

  2. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Source: http://science.jrank.org/pages/1331/Cellular-Respiration.html

  3. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Thank you!

  4. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    No problem! What did you get?

  5. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.