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How does the permeability differ between the outer and inner membrane of the mitochondrial membrane?

How does the permeability differ between the outer and inner membrane of the mitochondrial membrane?

The outer membrane has many protein-based pores that are big enough to allow the passage of ions and molecules as large as a small protein. In contrast, the inner membrane has much more restricted permeability, much like the plasma membrane of a cell.

Why is the inner membrane of mitochondria less permeable?

This is because it contains proteins called porins, which form channels that allow the free diffusion of molecules smaller than about 6000 daltons. The composition of the intermembrane space is therefore similar to the cytosol with respect to ions and small molecules.

Why does the mitochondrial inner membrane have a low passive permeability to most ions?

Foremost among these tasks is the continuous production of ATP through oxidative phosphorylation, which requires a large electrochemical driving force for protons across the mitochondrial inner membrane. This process requires a membrane with relatively low permeability to ions to minimize energy dissipation.

How permeable is the outer mitochondrial membrane?

The high permeability of the outer membrane is mediated by VDAC, which is the most common protein in the outer membrane and is permeable to molecules of up to 5000 daltons in its open configuration.

Is the inner mitochondrial membrane permeable?

Permeability. The inner membrane is freely permeable to oxygen, carbon dioxide, and water only. It is much less permeable to ions and small molecules than the outer membrane, creating compartments by separating the matrix from the cytosolic environment. This compartmentalization is a necessary feature for metabolism.

Why is the outer membrane of mitochondria porous?

Responsible for the extremely high permeability of the mitochondrial outer membrane is the presence of a pore-forming protein termed mitochondrial porin. Eukaryotic porins are slightly anion-selective in the open state but become cation-selective after voltage-dependent closure.

Is outer mitochondrial membrane permeable to protons?

The outer membrane is freely permeable to protons, which allows protons to move quickly into the intermembrane space, lowering the pH of this compartment. These conditions quickly set up a proton gradient across the inner mitochondrial membrane.

What are the inner and outer membranes of mitochondria made up of?

They are made of two membranes. The outer membrane covers the organelle and contains it like a skin. The inner membrane folds over many times and creates layered structures called cristae. The fluid contained in the mitochondria is called the matrix.

What does the outer membrane do in the mitochondria?

The mitochondrial outer membrane separates the intermembrane space from the cytosol. The whole exchange of metabolites, cations and information between mitochondria and the cell occurs through the outer membrane.

Is inner mitochondrial membrane permeable?

The mitochondrial inner and outer membranes have contrasting permeability characteristics. The outer membrane is non-specifically permeable to all low-molecular-weight solutes, whereas the inner membrane is impermeable except through specific transporters.

Why is the inner membrane larger than the outer membrane?

For typical liver mitochondria, the area of the inner membrane is about 5 times as large as the outer membrane due to cristae. This ratio is variable and mitochondria from cells that have a greater demand for ATP, such as muscle cells, contain even more cristae.

Is the inner mitochondrial membrane permeable to protons?

What makes the inner mitochondrial membrane permeable to biochemicals?

It is permeable to most biochemical. 1. It contains a number of particles. 2. It bears carrier and other transport proteins. 3. It contains a number of enzymes. 4. Inner mitochondrial membrane develops a large number of infolding’s called cristae. 5. Protein content is quite high (up to 80%) while lipid content is low.

How is calcium concentration related to mitochondrial permeability?

It is now known that increasing calcium concentration can largely relieve inhibition by CyA, while CyA-insensitive permeabilization of the mitochondrial membrane has been described ( Sultan and Sokolove, 2001 ).

What is the regulation of mitochondria in apoptosis?

D Regulation of Mitochondria in Apoptosis. Mitochondrial outer membrane permeabilization (MOMP) allows for selective release of molecules that participate in death. These molecules include cytochrome c, Smac/Diablo, HtrA2/Omi, and AIF.