Question

The respiratory enzymes are located in
A) Mitochondrial matrix
b) Peri Mitochondrial space
c) Cristae
d) Outer membrane

Answer 1

Respiration is a process in which organisms metabolize their food to produce energy. Respiration can be of two types- aerobic (occurs in presence of oxygen) and anaerobic (occurs in absence of oxygen) respiration. It has three steps- Glycolysis, Krebs cycle and electron transport chain. The enzymes of Krebs cycle are present in the mitochondrial matrix.

Complete answer: To answer this question, we must understand the structure of mitochondria:
Most eukaryotic cells contain mitochondria. The number of mitochondria varies with type of cell. They are membrane- enclosed cells and involved in energy production. It is hence called as the powerhouse of the cell.
It is believed that eukaryotic cells engulfed some prokaryotic cells which developed in mitochondria. This is called symbiotic theory.
Other functions of mitochondria are apoptosis, Calcium signaling and cellular differentiation.
Mitochondria has two phospholipid bilayers- the outer membrane and inner membrane. The inner membrane has infoldings called cristae. The space between the outer membrane and inner membrane is called peri mitochondrial space.
The outer membrane is phospholipid bilayer. It contains protein lipid composition which is similar to plasma membrane. It has a large integral membrane known as porins. These porins allow certain molecules to pass through facilitated diffusion.
The space between the outer membrane and inner membrane is called peri mitochondrial space, also known as intermembrane space .The outer membrane is permeable to small ions and molecules but not permeable to large molecules. Therefore the composition of proteins in cytosol is different than in intermembrane space.
The inner membrane contains a lot of proteins. It is impermeable to all ions and molecules, therefore it has integral proteins to allow them to pass through. It contains a series of proteins which form electron transport chains. These proteins are responsible for creating electrochemical gradients to produce ATP.
The mitochondrial matrix contains enzymes which are involved in Krebs’ cycle. The matrix also contains mitochondrial DNA. The enzymes present help in bringing about citric acid cycle, oxidative phosphorylation, oxidation of pyruvate and beta-oxidation of fatty acids. Since most of the enzymes are involved in citric acid cycle, oxidative phosphorylation which is a part of cellular respiration, hence they are respiratory enzymes
_>Thus the correct answer is option A) Mitochondrial matrix. _

Note: The process of cellular respiration begins with glycolysis. The process of glycolysis occurs in cytoplasm of the cell but the remaining half of the process takes place in mitochondria. ATP is synthesized in mitochondria.