6.5-mitochondria + chloroplasts change energy

• in eukaryotic cells, what organelles convert energy to forms that cells can use for work (energy)?

  mitochondria + chloroplasts
• define mitochondria

  sites of cellular respiration, the metabolic process that uses oxygen to drive generation of ATP by extracting energy from sugars, fats, and other fuels.
• define chloroplasts; include location and process

  found in plants and algae; sites of photosynthesis. converts solar energy to chemical energy by absorbing sunlight and using it to drive the synthesis of organic compounds such as sugars from carbon dioxide and water.
• Endosymbiont theory

  An early ancestor of eukaryotic cells (a host cell) engulfed an oxygen-using nonphotosynthetic prokaryotic cell. Eventually, the engulfed cell formed a relationship with the host cell in which it was enclosed, becoming an endosymbiont (a cell living within another cell). Indeed, throughout evolution, the host cell and its endosymbiont merged into a single organism, a eukaryotic cell with the endosymbiont having become a mitochondrion. At least one of these cells may have then taken up a photosynthetic prokaryote, becoming the ancestor of eukaryotic cells that contain chloroplasts.
• chloroplasts have what inside?

  internal system of membranous sacs
• like something, what do the mitochondria and chloroplasts contain?

  ribosomes and circular DNA molecules (like bacterial chromosomes) associated with their inner membranes
• DNA in organelles programs synthesis of what on what


  some organelle proteins on ribosomes that have been synthesized and assembled
• are chromosomes + mitochondria autonomous or non-autonomous?

  autonomous (somewhat independent) organelles that grow and reproduce within the cell
• the number of mitochondria correlates with the cell's what?

  level of metabolic activity - some cells have single large mitochondrion, others have hundreds
• cells that move or contract have proportionally more mitochondria per volume than less active cells
• what are each of the two membranes enclosing the mitochondrion?

  phospholipid layer with unique collection of embedded proteins
• mitochondria's outer membrane- texture

  smooth
• mitochondrion's inner membrane

  convoluted (complex); contains infoldings called cristae
• the inner membranes divide the mitochondrion into two internal compartments. what is the first intermembrane space like?

  narrow region between the inner and outer membrane
• what does the second compartment of the inner membrane of mitochondrion contain? what is the name?

  mitochondrial matrix - enclosed by the inner membrane; matrix contains many different enzymes & mitochondrial DNA and ribosomes.
• within the second compartment of inner membrane of mitochondrion, what do the enzymes and other proteins do? how about the cristae?

  Enzymes in matrix catalyze some of the steps of cellular respiration. Other proteins that function in respiration, including the enzyme that makes ATP, are built into the inner membrane. As highly folded surfaces, the cristae (outer membrane) give the inner mitochondrial membrane a large surface area, thus enhancing the productivity of cellular respiration. This is another example of structure fitting function
• Chloroplasts contain the green pigment chlorophyll, along with enzymes and other molecules that function in the photosynthetic production of sugar. These lens-shaped organelles, about 3–6 μm in length, are found in leaves and other green organs of plants and in algae
• contents of chloroplast are partitioned (divided) from the cytosol by an envelope consisting of two membranes separated by a very narrow intermembrane space
• Inside the chloroplast is another membranous system in the form of flattened, interconnected sacs called thylakoids
• what are each stack of thylakoids called?

  granum (plural - grana)

  in some regions, thylakoids stacked like poker chips
• what is the fluid outside thylakoids? what does it contain?

  stroma - contains the chloroplast DNA, ribosomes, and many enzymes.
• membranes of the chloroplast divide the chloroplast space into how many compartments? list them. why do the compartments exist?

  3 compartments: the intermembrane space, the stroma, and the thylakoid space. This compartmental organization enables the chloroplast to convert light energy to chemical energy during photosynthesis.
• can chloroplast and mitochondria move around within the cell?

  Yes: move around the cell along the tracks of the cytoskeleton
• chloroplast is a specialized member of a family closely related to what?

  plant organelles called plastids
• what are the types of plastids?

  1: amyloplast - colorless organelle that stores starch (amylose), particularly in roots and tubers.

  2. chromoplast - has pigments that give fruits & flowers their orange and yellow hues.
• what is a peroxisome? what does it contain?

  a specialized metabolic compartment bounded by a single membrane containing enzymes that remove hydrogen atoms from various substrates and transfer them to oxygen (O2 ), producing hydrogen peroxide (H2 O2 ) as a by-product (from which the organelle derives its name)
• Some peroxisomes use oxygen to break fatty acids down into smaller molecules that are transported to mitochondria and used as fuel for cellular respiration
• Peroxisomes in liver detoxify alcohol by transferring hydrogen from poisonous compounds to oxygen. The H2O2 formed by peroxisomes is itself toxic, but the organelle also contains an enzyme that converts H2O2 to water. The enzymes that produce H2 O2 and those that dispose of this toxic compound are sequestered away from other cellular components that could be damaged.
• what are the specialized peroxisomes and where are they found?

  glyoxysomes - found in the fat-storing tissues of plant seeds.
• what do the glyoxysomes contain?

  enzymes that initiate conversion of fatty acids to sugar, which the emerging seedling uses as a source of energy and carbon until it can produce its own sugar by photosynthesis.
• how do peroxisomes grow larger?

  by incorporating proteins made in the cytosol and ER (endoplasmic reticulum), as well as lipids made in the ER and within the peroxisome itself.