BIOL1006 Lecture Notes - Lecture 18: Symbiogenesis, Cellular Respiration, Alphaproteobacteria
Document Summary
One of the major features distinguishing prokaryotes from eukaryotes is the presence of mitochondria. Mitochondria are double-membraned organelles that contain their own ribosomes and dna. Each membrane is a phospholipid bilayer embedded with proteins. Eukaryotic cells may contain anywhere from one to several thousand mitochondria, depending on the cell"s level of energy consumption. Each mitochondrion measures 1 to 10 micrometers in length and exists in the cell as an organelle that can be ovoid to worm-shaped to intricately branched. Most mitochondria are surrounded by two membranes, which would result when one membrane-bound organism was engulfed into a vacuole by another membrane-bound organism. The mitochondrial inner membrane is extensive and involves substantial infoldings called cristae that resemble the textured, outer surface of alpha- proteobacteria. The matrix and inner membrane are rich with the enzymes necessary for aerobic respiration. This electron micrograph shows a mitochondrion as viewed with a transmission electron microscope. This organelle has an outer membrane and an inner membrane.
