Respiration

• Respiration


  Respiration is the controlled release of energy from food.
• Anaerobic


  Absence of oxygen
• Aerobic


  Requires oxygen
• The word equation for respiration is Glucose + Oxygen --> Carbon Dioxide + Water + ATP. What is the chemical equation?


  C6H1206 + H20 --> 6CO2 + H20 + ATP
• Mitrochondria


  The mitochondria are rod-shaped structures found in both plant and animal cells. They are the site of respiration in the cell.
• Where is mitochondria often found?

  Active cells, such as muscle cells in animals and meristem tissues in plants, contain lots of mitochondria because they require a lot of energy.
• Why is mitochondria called the powerhouse of the cell?

  Because aerobic respiration takes place within the mitochondria which produces a lot of ATP.
• Structure of a mitochondrion

  Mitochondrion has a double membrane structure. The outer membrane is smooth and the inner membrane is highly folded. The space inside the mitochondrion is called the lumen.
• How is ATP formed?

  When a phosphate group is added to ADP. This reaction also forms a water molecule
• What composes ATP?


  Adenine, one ribose unit, and three phosphates
• How is ATP broken down?

  ATP gets converted to ADP when the bond between the second and third phosphate groups breaks.
• Role of ATP in respiration

  Glucose is broken down and the energy released is used to form ATP.
• Advantages of ATP


  Available for immediate use

  Energy from ATP can be reused and recycled easily
• NAD+


  NAD+ stands for nicotinamide adenine dinucleotide, andit is a low-energy molecule used during respiration.
• NADP+


  NADP+ stands for nicotinamide adenine dinucleotide phosphate, and it is a low-energy molecule used during photosynthesis.
• What are NAD+ and NADP+ converted to?

  NAD+ and NADP+ gain two electrons and are converted to the negatively charged molecules, NAD- and NADP-.
• How is NADH created?

  NAD- can combine with two protons to become the high-energy molecule NADH which is used in respiration.
• How is NADPH created?

  NADP- can combine with two protons to become the high-energy molecule NADPH which is used in photosynthesis.
• Glycolysis


  Glycolysis is the breakdown of the 6-carbon sugar, glucose, into two 3-carbon molecules known as pyruvic acid.
• Where does glycolysis occur?

  Cytosol of the cell
• Products of glycolysis


  2 x ATP molecules,

  2 x NADH molecules,

  2 x pyruvic acid molecules
• What happens in the Krebs cycle?

  Krebs cycle involves the breakdown of a 2-carbon molecule, known as Acetyl coenzyme A into NADH, CO2, and ATP.
• Where does Krebs Cycle occur?

  Lumen of mitochondria
• What must occur before the Krebs Cycle can begin?

  Pyruvic acid loses a molecule of carbon dioxide, two electrons and one proton. This results in the formation of the 2-carbon molecule Acetyl Coenzyme A
• Events in the Krebs Cycle

  Acetyl CoA enters the Krebs cycle and is broken down in several steps to release high energy electrons and protons

  NAD+ traps these electrons and protons to produce the high energy molecule NADH

  Two molecules of carbon dioxide and one molecule of ATP are also formed from the breakdown of ATP
• Fate of ATP, Carbon Dioxide, and NADH following Krebs Cycle

  ATP later broken down to provide energy for cellular activities

  Carbon dioxide released into atmosphere, can be used for photosynthesis by plants

  NADH transfers electrons and protons to the electron transport system
• Products of Krebs cycle

  2 carbon dioxide molecules

  3 NADH molecules

  1 ATP molecule
• Electron Transport System


  A series of electron acceptor carries. Involves the transfer of electrons along a series of electron acceptor carriers to produce a vast amount of ATP.
• Events in the electron transport system

  NADH molecules formed during glycolysis and the Krebs Cycle are transported to the inner membrane of the mitochondria

  The high-energy electrons are passed from the NADH molecule to the first of the electron acceptor carriers

  As electrons are passed from carrier to carrier, they release energy into the intermembrane space, and this energy is used to make ATP from ADP and a phosphate

  The rest of the energy not used to create ATP is lost as heat
• Role of oxygen in aerobic respiration

  Electrons lose their energy at the end of the cycle. These low-energy electrons combine with the protons (trapped by NADH) and oxygen to form a water molecule (H2O). Oxygen is needed to remove the low-energy electrons at the end of the transport system.