Question

Understand oxidative energy production diagram beginning from glucose through the Krebs Cycle. How is energy producing molecules produced, and how energy is extracted from them? What are the key intermediate compounds, ie. key points at which protein and fats can enter into the energy producing cycle?

Answer 1

Krebs cycle/ citric acid cycle :

Def : The citric acid cycle also known as the TCA cycle or the Krebs cycle is a series of chemical reactions used by all aerobic organisms to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins, into adenosine triphosphate and carbon dioxide.

Production of ATP and NADPH :

  the first step of the cycle, acetyl co A combines with a four-carbon acceptor molecule, oxaloacetate, to form a six-carbon molecule called citrate. After a quick rearrangement, this six-carbon molecule releases two of its carbons as carbon dioxide molecules in a pair of similar reactions, producing a molecule of NADH The enzymes that catalyze these reactions are key regulators of the citric acid cycle, speeding it up or slowing it down based on the cell’s energy need

The remaining four-carbon molecule undergoes a series of additional reactions, first making an molecule—or, in some cells, a similar molecule called then reducing the electron carrier FADstart text, This set of reactions regenerates the starting molecule, oxaloacetate, so the cycle can repeat.

Overall, one turn of the citric acid cycle releases two carbon dioxide molecules and produces three NADH, FADH,2FADH ATP, GTP

Intermediate compounds are :

citrate, iso-citrate, alpha-ketoglutarate, succinate, fumarate, malate, and oxaloacetate