Citric Acid Cycle (Krebs Cycle)

Step 1

Acetyl CoA joins with a four carbon molecule, oxaloacetate, releasing the CoA group and forming a six-carbon molecule (citrate)

Step 2

Citrate is converted into its isomer isocitrate - removing water and then adding a water molecule

Step 3

Isocitrate is oxidized and releases a molecule of carbon dioxide, leaving behind a five-carbon molecule—a-keotglutarate - NAD⁺ is reduced to form NADH

Step 4

a-ketoglutarate becomes oxidized, reducing NAD⁺ to NADH and releasing a molecule of carbon dioxide - the remaining four-carbon molecule picks up coenzyme A, forming CoA (a-ketoglutarate dehydrogenase

Step 5

CoA is replaced by a phosphate group, which is then transferred to ADP to make ATP

Step 6

Succinate is oxidized, forming another four-carbon molecule called fumarate - two hydrogen atoms (with electrons) are transferred to FAD, producing FADH₂ (process is embedded in the inner membrane of the mitochondrion)

Step 7

Water is added to the four-carbon molecule fumarate, converting it into another four-carbon molecule called malate

Step 8

Oxalaoacetate (starting four carbon compound) is regenerated by oxidation of malate - another molecule of NAD⁺ is reduced to NADH in the process

What goes into the Kreb Cycle, what comes out?

Acetyl CoA goes in, ATP, NADH, FADH2, and CO² come out

Where in the cell does the Kreb Cycle occur?

Mitochondria