Question

The site of Krebs Cycle is
A) Cytoplasm
B) Mitochondrial matrix
C) Intermembrane space of mitochondria
D) Rackers particles

Answer 1

Hint: The Krebs Cycle is also known as tricarboxylic acid cycle (TCA) or Citric Acid Cycle (CAC).

Complete Answer:
Initiation of the Krebs Cycle starts with the glycolysis production in presence of the two 3-C molecules known as pyruvate. This 3-C molecule being acidic assigns an alternative name to the process of Krebs Cycle – Tricarboxylic Acid (TCA) Cycle.

1) Option a: In prokaryotes, Krebs cycle takes place in cytoplasm but not in the case of eukaryotes. Therefore, this is the incorrect option.

2) Option b: The entire process of the Krebs Cycle is governed by the powerhouse of the cell – mitochondria. Inside the mitochondrial matrix, the Krebs cycle reactions add on more numbers of electrons and protons to a possible number of electron carriers. These electrons and protons later find their fate into the process of ETC or Electron Transport Chain which ultimately gives rise to ATP production. It is then that our cell uses this ATP generated to power various cellular and inter-cellular reactions such as enzyme activation or protein transfer. This is the sole reason why mitochondria are often acknowledged as the powerhouse of the cell. Therefore, this is the correct option.

3) Option c: The intermembrane space of mitochondria holds the electrons which are to be pumped out of the matrix during electron transport. But it is not the site for Kreb’s cycle. Therefore, this is the incorrect option.

4) Option d: Rockets particles or F1 particles are globular shaped particles which have a stalk like structure. They act as ATP synthetases and they help in transport of electrons. But it is not the site for Kreb’s cycle. Therefore, this is the incorrect option.

Thus, the correct option is b) Mitochondrial matrix.

Note: For every 1 molecule of 3-C pyruvate added into the Krebs Cycle, the output generated are – 3 molecules of NADH, 1 molecule of GTP, 2 molecules of Carbon dioxide and 1 molecule of FADH.