Mitochondria are known as powerhouses of the cell. Adenosine triphosphate, or ATP, the energy-rich substance that powers essential cell activities, is produced primarily by the mitochondria in all eukaryotes that do not rely on photosynthesis.
In addition to ATP synthesis and cellular respiration, the formation of GTP and NADH in the citric acid cycle, the synthesis of amino acids, iron-sulfur clusters, and heme groups, and the production of phospholipids are some of the essential functions that mitochondria perform.
The respiratory chain membrane protein complexes and the mitochondrial ATP synthase in the inner membrane cristae function together to convert biological energy in mitochondria.
Table of Contents
Definition
There is an inner membrane and an outer membrane in the mitochondria. The mitochondrial inner membrane (IMM) is the location for the electron transport chain, a crucial step in aerobic respiration. The intermembrane space or gap is found between the inner and outer membranes. A proton potential is generated by accumulating H+ ions, which helps in ATP formation.
ATP is referred to as the cell’s energy currency. It is produced by ATP synthase, an enzyme within the inner mitochondrial membrane. Cells require this ATP component to fuel all of their essential functions.
Structure
The inner mitochondrial membrane is intricately folded and segmented in structure. The multiple membrane invaginations are known as cristae. The crista junctions separate cristae by juxtaposing the inner boundary membrane to the outer membrane.
Compared to a smooth inner membrane, cristae considerably increase the entire membrane surface area, increasing the available site for oxidative phosphorylation.
The matrix is the more enclosed space inside the inner membrane. The intermembrane space between the inner and outer membranes is mainly continuous with the cytosol.
Cristae
Small, spherical protein complexes or F1 particles, the sites of proton gradient-driven ATP production, are embedded on the matrix side of cristae membranes. Cristae impact overall mitochondrial chemiosmotic function.
Due to cristae, the inner membrane of normal liver mitochondria has an area about five times larger than the outer membrane.
Cristae Junctions
Junctions separate cristae from the inner border membranes. Transmembrane protein complexes that connect opposite cristae membranes in a bottleneck-like pattern and link head to head close the end of cristae partially.
Composition
Like the cell membrane, the inner mitochondrial membrane mainly consists of a bilayer of phospholipids. Different proteins that function to carry out the electron transport chain are embedded in this bilayer. The membrane has cristae, which increase the membrane’s surface area.
The protein-to-lipid ratio in the inner mitochondrial membrane is 80:20, while that in the outer membrane is 50:50.
Function and Permeability
The inner mitochondrial membrane preserves the proton gradient that powers oxidative phosphorylation and serves as a functional barrier to the movement of smaller molecules between matrix and cytosol.
The inner mitochondrial membrane (IMM) functions as a chemical and electrical insulator. It creates compartments by dividing the matrix from the cytosolic environment because it is significantly less permeable to small molecules and ions than the outer membrane. IMM is freely permeable to carbon dioxide, oxygen, and water only.
Specific compounds can pass across this barrier due to specialised ion transporters. The inner membrane contains many antiport systems that enable anions to be exchanged between the mitochondrial matrix and the cytosol.
Related Links:
Main Page: BYJU’S NEET
Comments