Mitochondrion Mitochondria Structural Features The inner membrane is protein rich (4:1 protein:lipid).not permeable Inner > Membrane and contains within it the Outer electron transporter,ATP Membrane synthase,membrane transport proteins. NThe outer membrane is readily permeable to molecules with Cristae molecular weights below 10,000 Da. Matrix Figure 1Mitochondrion The inner membrane is protein rich (4:1 protein:lipid). not permeable and contains within it the electron transporter, ATP synthase, membrane transport proteins. The outer membrane is readily permeable to molecules with molecular weights below 10,000 Da.