TCA cycle

Question 1

step 1

Answer 1

pyruvate (3C) is decarboxylated to acetyl CoA (2C)
 Release of 1 CO2
 Production of 1 NADH

Question 2

step 2

Answer 2

 The acetyl (2C) of Acetyl CoA is combined with oxaloacetate (4C) to produce citrate (6C)
 Deacetylated CoA recycled redy fro next acetyl “load” from pyruvate

Question 3

step 3

Answer 3

• citrate is isomerised to isocitrate

Question 4

step 4

Answer 4

 Iso citrate (6C) is oxidized to a-ketogluterate (5C)
 Coupled to reduction of 1 NAD+ to NADH
 Release of 1 CO2

Question 5

step 5

Answer 5

 A- ketoglutarate (5C) is oxidized to succunyl CoA (4C)
 Coupled to reduction of another NAD to NADH
 Release of 1 CO2
*last of 3 carbons in original pyruvate oxidized to CO” and 3 NADH produced by the end of step 5

Question 6

after step 5 what happens

Answer 6

the rest of the TCA cycle is to convert succinyl CoA back to oxaloacetate

Question 7

step 6

Answer 7

 Succinyl CoA is converted to succinate
 Production of 1 GTP (equivalent to 1 ATP)
 Only substrate- level phosphorylation of TCA cycle

Question 8

step 7

Answer 8

 Succinate is oxiaded to fumarate
 Coupled to reduction of FAD to FADH
only step where reduced product FADH and product (fumarate) start with an F

Question 9

step 8

Answer 9

furmarate is converted to malate

Question 10

step 9

Answer 10

• Malate is oxidized to oxaloacetate
• Production of 1 NADH (last of 4/pyruvate)
• Oxaloacetate can now be combined with acetyl CoA to form citrate
• The cycle begins again