Energy Converting Organelles

• Mitochondria and chloroplasts change energy from one form to another.
• Mitochondria are the sites of cellular respiration, a metabolic process that uses oxygen to generate ATP.
• Chloroplasts, found in plants and algae, are the sites of photosynthesis.
• Mitochondria and chloroplasts have similarities with bacteria

  • Enveloped by a double membrane
  • Contain free ribosomes and circular DNA molecules
  • Grow and reproduce somewhat independently in cells
• The Endosymbiont Theory is the idea that the mitochondria and chloroplasts are the remains of a symbiotic relationship between a prokaryotic cell and an eukaryotic cell.
• The word endo means within while symbiont means an organism living in symbiosis with another organism.
• Mitochondria are in nearly all eukaryotic cells.
• Mitochondria have a smooth outer membrane and an inner membrane folded into cristae.
• The inner membrane creates two compartments: intermembrane space and mitochondrial matrix.
• Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix.
• Cristae present a large surface of enzymes that synthesize ATP.
• The intermembrane space is the narrow region between the inner and outer membranes.
• The mitochondrial matrix contains

  • the mitochondrial DNA
  • ribosomes
  • and many enzymes that catalyze some of the reactions of cellular respiration.
• Chloroplasts contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis.
• Chloroplasts are found in leaves and other green organs of plants and in algae.
• The chloroplasts is one of a group of plant organelles called plastids.
• Between the outer and inner membrane is a thin intermembrane space.
• Inside the inner membrane is:

  • stroma
  • thylakoids
  • granum
• A thick fluid called stroma that contains the chloroplasts, DNA, ribosomes, and many enzymes.
• A network of interconnected sacs called thylakoids - contain chlorophyll.
• In some regions, thylakoids are stacked like poker chips. Each stack is called a granum, where green chlorophyll molecules trap solar energy.
• Mitochondria supply energy to the cell. They are round-to-oval shaped organelles and have two membranes.
• Unlike other organelles, mitochondria have their own ribosomes and DNA.
• human - mitochondria (to produce ATP (energy))

  plants and algae - chloroplast (photosynthesis) and mitochondria (cell respiration)