what does the first membrane mentioned consist of?
It contains large numbers of integral membrane proteins called porins.
Mitochondrion
It contains large numbers of integral membrane proteins called porins.
where is the mitochondria located in an animal cell UNANSWERABLE what is the main topic in discussion? Mitochondrion. what is it's structural composition? They contains outer and inner membranes composed of phospholipid bilayers and proteins, that have different properties. Because of this double-membraned organization, there are five distinct parts to a mitochondrion.
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Mitochondrion [SEP] Outer membrane
The outer mitochondrial membrane, which encloses the entire organelle, is 60 to 75 angstroms (Å) thick. It has a protein-to-phospholipid ratio similar to that of the cell membrane (about 1:1 by weight). It contains large numbers of integral membrane proteins called porins. A major trafficking protein is the pore-forming voltage-dependent anion channel (VDAC). The VDAC is the primary transporter of nucleotides, ions and metabolites between the cytosol and the intermembrane space. It is formed as a beta barrel that spans the outer membrane, similar to that in the gram-negative bacterial membrane. Larger proteins can enter the mitochondrion if a signaling sequence at their N-terminus binds to a large multisubunit protein called translocase in the outer membrane, which then actively moves them across the membrane.