Mitochondria

Structure

• Various shapes, often cylinders 1 to 10µm long.
• Two membrane layers, each a phospholipid bilayer.
• Many special proteins embedded in membranes.
• Outer membrane smooth, inner membrane convoluted and folded.
• Creates two internal compartments, one between the membranes, the other inside inner membrane.
• Often 100's or 1000's of mitochondria per cell.
• More in cells with high metabolic demands (muscle cells).

Function

• Site of cellular respiration (creates energy for cell).
• Respiration is extracting energy with oxygen from sugars, fats, etc.
• Energy made available to cells in the form of ATP.

History (endosymbiont theory)

• Mitochondria have their own DNA !?
• Replicate independent of the cell.
• Cell membrane, nucleus and ribosomes come from an ancestral archaeon.
• Mitochondria and chloroplasts are bacteria whose ancestors were absorbed in the Precambrian.
• Over time, the endosymbionts (internal dwellers) lost the ability for an independent life.
• Mitochondrial genome arose from a purple bacterium.
• Plastid genome arose from a cyanobacterium.