5.7.4 the link reaction & Krebs cycle Flashcards
decarboxylation
removal of carboxyl group from substrate molecule
dehydrogenation
removal of hydrogen atoms from substrate molecule
substrate-level phosphorylation
production of ATP from ADP & Pi during glycolysis & Krebs cycle
where is pyruvate from glycolysis transported to
across outer & inner mitochondrial membranes via specific pyruvate-H+ symport into the matrix
symport
transport protein that transports 2 ions or molecules in same direction
what happens to pyruvate in the links reaction & Krebs cycle
- pyruvate converted into 2C acetyl group during link reaction
- acetyl group oxidised during Krebs cycle
where does the link reaction occur
mitochondrial matrix
what happens to pyruvate in the link reaction
becomes decarboxylated & dehydrogenated, catalysed by pyruvate dehydrogenase
is ATP produced in the link reaction
no
describe the steps involved within link reaction
- carboxyl group removed from pyruvate - decarboxylation
- decarboxylation & dehydrogenation of pyruvate (to produce NADH) produces acetyl group
- acetyl group combines with coenzyme A producing acetyl coenzyme A
how many times does the link reaction occur for 1 glucose molecule
2x (2 pyruvate produced in glycolysis)
products of the link reaction for 1 molecule of glucose
- 2 acetyl CoA
- 2 carbon dioxide (CO2)
- 2 NADH
link reaction for 2 molecules of pyruvate (1 glucose molecule) as an equation
2 pyruvate + 2NAD + 2CoA —> 2CO2 + 2NADH + 2 acetyl CoA
where does the Krebs cycle occur
mitochondrial matrix
role of reduced coenzymes produced in Krebs cycle
carry hydrogen atoms to electron transport chain on cristae (oxidative phosphorylation)
describe the 6 steps of the Krebs cycle
- acetyl group (2C) from acetyl CoA combines with 4C oxaloacetate = citrate (6C)
- citrate decarboxylated & dehydrogenated producing 5C compound & one molecule of carbon dioxide, as well as NADH
- 5C compound decarboxylated & dehydrogenated producing 4C compound & one molecule of carbon dioxide, as well as NADH
- substrate-level phosphorylation producing 1 molecule of ATP
- 4C compound dehydrogenated producing different 4C compound & FADH
- rearrangement of atoms in 4C compound (catalysed by isomerase enzyme) followed by dehydrogenation, regenerate a molecule of oxaloacetate & cycle continue
how many turns of Krebs cycle for 1 molecule of glucose
2
products of Krebs cycle for 1 glucose
for 1 glucose:
- 4 carbon dioxide
- 6 NADH
- 2 FADH
- 2 ATP
name 4 different coenzymes
- FAD
- NAD
- ATP
- acetyl coenzymes A
