1. Chapter 9

2.  Cellular respiration Cellular respiration  Anaerobic respiration Anaerobic respiration  Importance of oxygen Importance of oxygen

3.  The foods we, and other animals eat, provide the raw materials needed for cells to synthesize new molecules.  These molecules will serve as the building blocks needed for growth and development of new cells.  Foods also provide energy for the cells in living things.

4.  An essential roll of foods is to provide the living thing with the energy to carry out the daily activities of life.  Foods provide the chemical energy needed by the cells of living things.

5.  The energy in foods is measured in calories.  A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius.

6.  The Calorie (capital “C”) that is used on food labels is a kilocalorie, or 1000 calories.

7.  Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presences of oxygen.

8.  Glycolysis  Krebs cycle  Electron transport phosphorylation (occurs in electron transport chain)

9.  6O 2 + C 6 H 12 O 6 -------  6CO 2 + H 2 O + energy Oxygen + glucose produces carbon + water + energy dioxide  Cellular respiration  Requires food and oxygen  Produces carbon dioxide and energy

10.  Glycolysis  Krebs cycle  Electron transport chain

11.  Glycolysis is the process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid, a 3-carbon compound.

12.  Requires 2 molecules of ATP  Produces:  4 ATP for a net gain of 2 ATP  NADH  Pyruvic acid  Takes place in the cytoplasm.  Very fast process that produces thousands of ATP in a few milliseconds.  Does not require oxygen.  Problem – the available NAD+ molecules become filled with ATP and the cell cannot keep glycolysis going.

13.  Process of producing ATP in the absence of oxygen.  cells convert NADH to NAD + by passing high- energy electrons back to pyruvic acid.  Process is said to be anaerobic, “not in air.”  Two types of fermentation:  Alcohol fermentation  Lactic acid fermentation

14.  Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes.  Produces carbon dioxide as well as alcohol.  Alcoholic fermentation causes bread dough to rise.

15.  the pyruvic acid that accumulates as a result of glycolysis can be converted to lactic acid.  This process regenerates NAD + so that glycolysis can continue.

16.  Vigorous exercise can cause the accumulation of lactic acid in large muscles, leading to muscle soreness.

17.  Unicellular organisms also produce lactic acid as a waste product during fermentation.  Prokaryotes are used in the production of a wide variety of foods and beverages, such as cheese, yogurt, buttermilk, and sour cream.

18.  In the presence of oxygen, pyruvic acid produced in glycolysis passes to the second stage of cellular respiration, the Krebs cycle.  Named after Hanes Krebs.

19.  Pyruvic acid is broken down into carbon dioxide in a series of energy- extracting reactions.  Citric acid is the first compound formed in this series of reactions,

20.  The term cellular respiration refers to energy- releasing pathways within the cell  Oxygen is required for the final steps of cellular respiration. Because the pathways of cellular respiration require oxygen, they are said to be aerobic (with oxygen).  Takes place inside the mitochondria.

21.  Begins when pyruvic acid produced by glycolysis enters the mitochondrion.  The other two carbon atoms from pyruvic acid are joined to a compound called coenzyme A to form acetyl-CoA.  Acetyl-CoA adds the 2- carbon acetyl group to a 4-carbon molecule, producing a 6-carbon molecule called citric acid.

22.  Citric acid (6-carbon molecule) is broken down into a 5-carbon compound.  A second carbon is removed forming a 4- carbon compound.  With each change carbon dioxide is released, and electrons are transferred to energy carriers (NAD+ and FAD).

23.  With each cycle a molecule similar to ADP is turned into ATP.  CO 2 is removed from the body as the animal exhales.  The ATP produced directly in the Krebs cycle can be used for cellular activities.

24.  The 4-carbon molecule is ready to accept another 2-carbon acetyle group, starting the cycle over again.  The cell will use the high- energy electrons in NADH to generate large amounts of ATP in the electron transport chain.

25.  The electron transport chain uses the high- energy electrons from the Krebs cycle to convert ADP into ATP.  The beauty of this system is the way in which it couples the movement of high- energy electrons with the production of ATP.

26.  High-energy electrons from NADH and FADH 2 are passed along the electron transport chain.  At the end of the electron transport chain is an enzyme that combines these electrons with hydrogen ions and oxygen to form water.  Oxygen serves as the final electron acceptor of the electron transport chain.

27.  Every time 2 high-energy electrons transport down the electron transport chain, their energy is used to transport hydrogen ions (H + ) across the membrane.  During electron transport, H + ions build up in the intermembrane space, making it positively charged.  The other side of the membrane, from which those H + ions have been taken, is now negatively charged

28.  The inner membranes of the mitochondria contain protein spheres called ATP synthases.  As H + ions escape through channels into these proteins, the ATP synthases spin.  Each time it rotates, the enzyme grabs a low- energy ADP and attaches a phosphate, forming high-energy ATP

29.  The Krebs cycle and electron transport enable the cell to produce 34 more ATP molecules per glucose molecule, in addition to the 2 ATP molecules obtained from glycolysis.  Total ATP - 36

30.  Begin the race using ATP stored in the muscle cells.  After 10 sec. ATP produced by lactic acid fermentation.  After 90 sec. ATP is produce by cellular respiration, using O2.  Fuel source  15 – 20 min. – CHO  Longer 20 min – fats

31.  Photosynthesis is the process that “deposits” energy.  Cellular respiration is the process that “withdraws” energy.  Photosynthesis removes carbon dioxide from the atmosphere, and cellular respiration puts it back.  Photosynthesis releases oxygen into the atmosphere, and cellular respiration uses that oxygen to release energy from food.  The release of energy by cellular respiration takes place in all eukaryotes and some prokaryotes.  Energy capture by photosynthesis, however, occurs only in plants, algae, and some bacteria.