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Biology-Life Sciences

Standard G: Mitochondria
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Standard A: Plasma Membranes
Standard B: Enzymes
Standard C: Prokaryotic Cells, Eukaryotic Cells, and Viruses
Standard D: Central Dogma of Molecular Biology
Standard E : The endoplasmic reticulum and golgi apparatus
Standard F: Chloroplasts
Standard G: Mitochondria
Standard H: Macromolecules
Standard J : The Cytoskeleton and Cell Wall
Standard I : ATP production
Exemplar Chart
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Mitochondria

 

Mitochondria are membrane-bound organelles in both plant and animal cells that transform and break down the energy that the chloroplasts trap.  The process where mitochondria breaks down food molecules to make ATP(adenosine triphosphate) is called cellular respiration.  Mitochondria have an outer membrane and a multiply folded inner membrane called the cristae.  The walls of the cristae are the site of the cell's energy production.  The membranes are similar to the membranes of the golgi apparatus and endoplasmic reticulum.  In the inner fold, energy-storing molecules are made.  Mitochondria occur in a variety of numbers, depending on what the function of the cell

 

mitochondriafigure1.jpg

Cellular Respiration

Cellular respiration is the chemical process where mitochondria break down food molecules to produce ATP.  The chemical equation for cellular respiration is

 

C6H12O6 + O2  CO2    + H2O + energy 

or 

Glucose + oxygen = carbon dioxide + water + ATP

There are three stages of cellular respiration: glycosis, the citric acid cycle, and the electron transport chain. 

  • Glycosis is the series of chemical reactions that occur in the cytoplasm.  This process breaks down glucose into simpler substances. In glycosis, six carbon molecules make two sets of three carbon molecules.  This process uses two molecules of ATP.  The product of glycosis is four molecules of ATP and one of NADH. Cytosol helps to control the cell's metabolism because of the proteins found in it.
  • The citric acid cycle (Krebs cycle) is a series of chemical reactions that break down glucose and produce ATP.  It occurs in the mitochondria.  One of the sets of the three-carbon molecules travel over to the mitochondria.  On the way there, one carbon molecule breaks off and detaches.   The now two-carbon molecule joins up with four carbons to make citric acid.   One molecule of ATP is released (one per turn), followed by one molecule of NADH and one molecule of carbon dioxide.  After, two more molecules of NADH are released, one molecule of FADH2, and on molecule of carbon dioxide.    NADH and FADH2 are both energy carriers in the form of Hydrogen and electrons. Therefore, the products of this chemical reaction is three molecules of NADH, one molecule of ATP, and one molecule of FADH2. 
  • The third step of respiration is the electron transport chain.  The electron transport chain is located in the mitochondrial matrix.  The electron transport chain has a pathway for all the electrons to travel.  The NADH and FADH2 go into the mitochondrial matrix and drop off the energy they were carrying. When they lose their energy, they become NAD and FAD, respectively.  Each time the electron moves, it loses one hydrogen ion.  When the electrons reach their destination, the final equation is O2 + H2 > H2O.

The process of cellular respiration results in 36 ATP molecules made