Lecture 5 - Krebs Flashcards
Site and purpose of Krebs
Still in the liver, but now in the mitochondrial matrix
- large pores in the outer membrane let pyruvate diffuse through but crossing the inner membrane requires a pyruvate-specific membrane carrier (this active transport is powered by entropy created by liberating CO2 and extra energy is avaliable to reduce NAD+)
Step 1 of Krebs
2 Pyruvate (3C) enter from glycolysis
- NAD+ to NADH
- losses a Carbon (as CO2) and add coA to form acetyl-coA
enzyme: pyruvate dehydrogenase
purpose of acetyl-coA
so that the pyruvate can enter the mitochondrial membrane and then the matrix
Step 2 of Krebs
Acetyl-coA binds to Oxaloacetate (oaa) to form citrate
- removal of coA
enzyme: citrate synthase
Step 3 of Krebs
- Rearranged 6C citrate into isocitrate through removal and addition of water
enzyme: aconitase
Step 4 of Krebs
lose C (in the form of CO2) to form alpha-ketogluturate (5C)
- NAD+ to form NADH
enzyme: iso-citrate dehydrogenase
Step 5 of Krebs
Lose a C (in the form of CO2) and gain coA to form succinyl coA (4c)
NADH formation
enzyme: alpha-ketoglutarate dehydrogenase
Step 6 of Krebs
remove coA to form succinate (4C)
- GDP turns into GTP from the energy released via coA removal and Pi
- GTP can be converted to ATP
- Pi remains, hangs out
enzyme: succinyl coA synthase
Step 7 of Krebs
Succinate forms Fumuarate (4C)
- formation of FADH2 and FAD
enzyme: succinate dehydrogenase
Step 8 of Krebs
Fumarate turns into malate and + H2O
enzyme: Fumuarase
Step 9 of Krebs
Malate forms OAA via oxidation
- NAD+ to form NADH
enzyme: malate dehydrogenase
Step 10 of Krebs
OAA is available to combine with acetyl-coA so that it regenerates the cycle
Without glucose what would happen to OAA
the body will turn it into glucose
Products
4 CO2
6 NADH
2 FADH2
2 ATP
Mnemonic for Krebs
Can I Keep Selling Substances For Money, Officer?
Citrate
Isocitrate
Alpha-ketoglutarate
Succinyl-CoA
Succinate
Fumarate
Malate
OAA
