can someone explain Cellular Respiration/Glycolysis/Krebs Cycle to me?

Question

I've been staring at my textbook for a long time at the same pages and I still really really reallyyy don't get it. Any help is appreciated, thanks! :)

Answer 1

Cellular respiration is the way all kinds of cells break down glucose molecules to make ATP molecules. The main stages are:

GLYCOLYSIS:
1. Happens in the cytoplasm.
2. Breaks one glucose into two molecules of pyruvate or pyruvic acid.
3. Needs 2 ATP to get started, and makes 4 ATP all together, so there is a net gain of 2 ATP. This means that the cell is "ahead" 2 ATP after glycolysis.
4. Puts some electrons on the carrier NAD+ to make a couple of NADH molecules for later.

There's a little transition phase after glycolysis and before the Krebs Cycle. The gain here is two more NADH.

KREBS CYCLE or Citric Acid Cycle
1. Main plan is to keep picking away at the pieces that are left at the glucose, getting rid of carbon dioxide molecules.
2. 2 ATP are made.
3. Electron carriers (6 NADH and 2 FADH2) are sent to electron transport chain.
4. This happens in the matrix or gel-like part of the mitochondria.

ELECTRON TRANSPORT CHAIN
1. Main idea is that the electrons from NADH and FADH2 from the preceding steps are passed along the electron transport chain. They give up energy to make ATP. At the end of the electron transport chain, the electrons join with H+ ions and oxygen to form water molecules. The oxygen is the electron acceptor that lets this process keep going. It's like the garbage man that takes away the garbage so the restaurant can stay in business. If a city has a garbage strike, things pretty much come to a halt. The oxygen has to take away the electrons after they finish going through the electron transport chain, or it will all just back up and screech to a halt. How far will it back up? Glycolysis can continue (if there's fermentation), but the transition phase, Krebs cycle, and electron transport chain will stop.
2. This happens in the inner membrane of the mitochondria.

Answer 2

Remember that electrons are negative ( - ) and protons are positive ( + )...H+ is a hydrogen minus an electron. My 1st year chem prof taught me this mnemonic for RedOx (reduction/oxidation)..."LEO says GER"...or Loss of an electron = oxidation and Gain of an electron = reduction. It's all about the electrons...the protons H+ are only acting as the transfer media for the electron transfer. Don't get caught up in what happens to the protons/H+...the important part is the electrons and the production of ATP through the redox reactions within the cycle.

Answer 3

thank you