Krebs/Citric acid Cycle

Question 0

Where does Krebs cycle occur?

Answer 0

~All cells with mitochondria (matrix)

~Except succinate dehydrogenase (inner membrane)

Question 1

Functions of the krebs cycle?

Answer 1

~Provides majority of ATP for energy
~Gluconeogenesis from skeletons of AA
~Building blocks for AA and Heme

Question 2

What is the substrate for krebs cycle?

Answer 2

~Acetyl Coa

Question 3

What are the products of the kreb cycle?

Answer 3

3 NADH
1 FADH
1 GTP
CO2

Question 4

Rate limiting step in Krebs cycle?

Answer 4

isocitrate > a - ketoglutarate

isocitrate dehydrogenase

Question 5

Mnemonic for Krebs cycle

Answer 5

Officer (oxaloacetate)
Can (citrate)
I (isocitrate)
Keep (a-ketoglutarate)
Selling (succ coa)
Sex (succinate)
For (fumarate)
Money (malate)

Question 6

a-ketoglutarate dehydogenase is a co-enzyme of?

Answer 6

pyruvate dehydrogenase (maarte)
-they have the same cofactors

B1 - Thiamine pyrophosphate
B2 - FAD
B3 - NAD
B5 - Coenzyme A
Lipoic acid

*can be inhibited by arsenite

Question 7

Step in krebs cycle that can be inhibited by fluoroacetate (rat poison)?

Answer 7

citrate > isocitrate “isomerization”

aconitase

Question 8

Steps in Krebs cycle that produces NADH?

Answer 8

isocitrate > a-ketoglutarate
(isocitrate dehydrogenase)*CO2

a-ketoglutarate > Succ Coa
(a-ketoglutarate dehydrogenase)*CO2

malate > oxaloacetate
(malate dehydrogenase)

Question 9

Step in krebs cycle that produces FADH?

Answer 9

succinate > Fumarate

succinate dehydrogenase

Question 10

Step in krebs cycle that pruduces GTP?

Answer 10

succinyl coa > succinate

succinate thiokinase

Question 11

Net ATP produce with 1 acetyl coa?

Answer 11

NADH 3x3 = 9
FADH 2x1 = 2
GTP 1x1 = 1
TOTAL = 12

Question 12

ATP produce during Krebs cycle with 1 mol of glucose?

Answer 12

NADH 1x3 = 3 (pyruvate > acetyl coa produces 1NADH)

NADH 3x3 = 9
FADH  2x1 = 2
GTP      1x1 = 1
                  = 15
                  x 2
          ToTal = 30 (1 mol of glucose produces 2 pyruvate so krebs cycle happens twice)

Question 13

Net ATP’s produced during a complete oxidation of 1 mol of glucose?

Answer 13

NADH 1x3 = 3 (pyruvate > acetyl coa produces 1NADH)

NADH 3x3 = 9
FADH  2x1 = 2
GTP      1x1 = 1
                  = 15
                  x 2
                  = 30 (1 mol of glucose produces 2 pyruvate so krebs cycle happens twice)   
                  30 + 6 or 8 (ATP from glycolysis)
       TOTAL = 36 (GSP) or 38 (MAS)