CITRIC ACID CYCLE-BI25M7(1)

Question 1

What is the Citric Acid Cycle also known as?

Answer 1

Krebs cycle or tricarboxylic acid (TCA) cycle

Question 2

Where does the Citric Acid Cycle occur?

Answer 2

In the mitochondrial matrix

Question 3

What is the primary function of the Citric Acid Cycle?

Answer 3

It is the common metabolic pathway for carbohydrates, fatty acids, and amino acids

Question 4

How much energy does the Citric Acid Cycle yield compared to glycolysis?

Answer 4

Much more energy than glycolysis

Question 5

What does the Citric Acid Cycle primarily produce?

Answer 5

NADH and FADH2

Question 6

Does the Citric Acid Cycle produce ATP directly?

Answer 6

No, it does not produce ATP directly

Question 7

What percentage of aerobic cell energy is produced in collaboration with oxidative phosphorylation?

Answer 7

90%

Question 8

What type of cycle is the Citric Acid Cycle classified as?

Answer 8

Amphibolic cycle

Question 9

What is the role of Acetyl CoA in the Citric Acid Cycle?

Answer 9

It allows different intermediates into the main energy-producing pathway

Question 10

What enzyme converts pyruvate to Acetyl CoA?

Answer 10

Pyruvate dehydrogenase

Question 11

What is the size of the pyruvate dehydrogenase complex?

Answer 11

50 nm across

Question 12

What are the three enzyme sub-units of pyruvate dehydrogenase?

Answer 12

E1, E2, E3

Question 13

What reaction is catalyzed by E1 in pyruvate dehydrogenase?

Answer 13

Decarboxylation of pyruvate

Question 14

What does the decarboxylation step of pyruvate dehydrogenase release?

Answer 14

Two electrons in the form of 2 H ions

Question 15

What do primitive organisms use O2 for in metabolism?

Answer 15

To oxidize food molecules further than glycolysis

Question 16

What compound is produced by the complete breakdown of high-energy food molecules like glucose?

Answer 16

CO2 and H2O

Question 17

What is the primary method of energy extraction from hexoses in primitive organisms?

Answer 17

Glycolysis

Question 18

How is entry into the Citric Acid Cycle controlled?

Answer 18

By pyruvate dehydrogenase and its products

Question 19

What negatively regulates isocitrate dehydrogenase?

Answer 19

ATP and NADH

Question 20

What positively regulates isocitrate dehydrogenase?

Answer 20

ADP

Question 21

What does a build-up of α-ketoglutarate indicate?

Answer 21

Switch to production of amino acids

Question 22

What is an anaplerotic reaction?

Answer 22

A reaction that fills up intermediates in the Citric Acid Cycle

Question 23

What does the Citric Acid Cycle provide for biosynthetic processes?

Answer 23

Building blocks for nucleotide bases, heme groups, and proteins

Question 24

What triggers the activity of pyruvate carboxylase?

Answer 24

Presence of Acetyl CoA

Question 25

How much CO2 does the average human produce per day?

Answer 25

540 L/day

Question 26

What is the molar density of CO2?

Answer 26

~0.05 mol/L

Question 27

What is Avogadro's number?

Answer 27

6.022 × 10^23

Question 28

What is the function of the electron transport chain in relation to the Citric Acid Cycle?

Answer 28

It produces large amounts of ATP from the energy transferred

Question 29

True or False: The Citric Acid Cycle requires oxygen as a reactant.

Answer 29

False

Question 30

Fill in the blank: The Citric Acid Cycle is a '______' because it serves both catabolic and anabolic processes.

Answer 30

amphibolic pathway