CELL RESPIRATION
STRUCTURE OF THE MITOCHONDRION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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freely permeable to molecules like ATP, NAD, and coenzyme A
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have large channels
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impermeable; all molecules and ions require special membrane transporters to gain entrance to the matrix.
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Detailed explanation-1: -The inner membrane of mitochondria is covered by numerous large protein complexes involved in cellular respiration. Thus, the protein to lipid ratio of the inner membrane is higher which makes it highly impermeable even for small ions.
Detailed explanation-2: -However, the inner mitochondrial membrane is not only impermeable to NADH and NAD+; it also contains no transport systems for these substances. Impermeability to NADH is overcome by indirect transfer of the reducing equivalents through shuttling substrates that undergo oxidation–reduction reactions.
Detailed explanation-3: -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.
Detailed explanation-4: -The inner mitochondrial membrane transduces energy through oxidative phosphorylation, the main process responsible for the production of energy in the form of ATP in eukaryotic cells (Saraste, 1999).