• Mitochondria & chloroplasts → Transform energy • Mitochondria (singular: mitochondrion) are the sites of cellular respiration → Use oxygen to make ATP from sugars, fats, and other fuels • Chloroplasts (In plants and algae): Sites of photosynthesis, solar energy converted to chemical energy

Mitochondria • Occur in most eukaryotic cells – Some cells have one big mitochondrion, more often cells have 100s-1000s • Correlates with cell’s level of metabolic activity • 2 membranes enclosing it → Each is a phospholipid bilayer with embedded proteins • Outer membrane is smooth • Inner membrane is convoluted – Infoldings are called CRISTAE • 2 inner compartments – Between the 2 membranes is the intermembrane space – Enclosed by inner membrane is mitochondrial matrix • Contains enzymes, mtDNA, ribosomes