Copyright Pearson Prentice Hall Biology Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 9-1 Chemical Pathways Photo Credit: Duomo Photography, Inc. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 9-1 Chemical Pathways Food serves as a source of raw materials for the cells in the body and as a source of energy. Animal Cells Animal Mitochondrion Plant Photo Credits: left: ©Bob Gurr/DRK Photo; middle bottom: ©John Durham/Science Photo Library/Photo Researchers, Inc. ; middle top: ©Ron Boardman/Stone; right: ©Keith Porter/Photo Researchers, Inc. Plant Cells Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Both plant and animal cells carry out the final stages of cellular respiration in the mitochondria. Outer membrane Intermembrane space Mitochondrion Animal Cells Inner membrane Photo Credits: left: ©Bob Gurr/DRK Photo; middle bottom: ©John Durham/Science Photo Library/Photo Researchers, Inc. ; middle top: ©Ron Boardman/Stone; right: ©Keith Porter/Photo Researchers, Inc. Plant Cells Matrix Copyright Pearson Prentice Hall

Chemical Energy and Food One gram of the sugar glucose (C6H12O6), when burned in the presence of oxygen, releases 3811 calories of heat energy. A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. Copyright Pearson Prentice Hall

Chemical Energy and Food Cells don't “burn” glucose. Instead, they gradually release the energy from glucose and other food compounds. This process begins with a pathway called glycolysis. Glycolysis releases a small amount of energy. Copyright Pearson Prentice Hall

Overview of Cellular Respiration If oxygen is present, glycolysis is followed by the Krebs cycle and the electron transport chain. Glycolysis, the Krebs cycle, and the electron transport chain make up a process called cellular respiration. Copyright Pearson Prentice Hall

Overview of Cellular Respiration What is cellular respiration? Copyright Pearson Prentice Hall

Overview of Cellular Respiration Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvic acid Glucose Glycolysis Cytoplasm Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place inside the mitochondria. Mitochondrion Copyright Pearson Prentice Hall

Overview of Cellular Respiration Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen. Copyright Pearson Prentice Hall

Overview of Cellular Respiration The equation for cellular respiration is: 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy oxygen + glucose → carbon dioxide + water + Energy Copyright Pearson Prentice Hall

Overview of Cellular Respiration Each of the three stages of cellular respiration captures some of the chemical energy available in food molecules and uses it to produce ATP. Copyright Pearson Prentice Hall

Overview of Cellular Respiration Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place in the mitochondria. Glycolysis Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place inside the mitochondria. Cytoplasm Mitochondrion Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Glycolysis What happens during the process of glycolysis? Copyright Pearson Prentice Hall

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

Copyright Pearson Prentice Hall Glycolysis ATP Production At the beginning of glycolysis, the cell uses up 2 molecules of ATP to start the reaction….energize it!! 2 ATP 2 ADP 4 ADP 4 ATP Glycolysis is the first stage in cellular respiration. During glycolysis, glucose is broken down into 2 molecules of pyruvic acid. Glucose 2 Pyruvic Acid Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Glycolysis When glycolysis is complete, 4 ATP molecules have been produced from 4 ADP molecules using the energy released from the breakdown of the glucose molecule. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Glycolysis This gives the cell a net gain of 2 ATP molecules. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Glycolysis NADH Production – One of the reactions of glycolysis removes 4 high-energy electrons and passes then to an electron carrier NAD + (taxi)…..each NAD+ accepts a pair 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid Glucose is oxidized…loses electrons in chemical reactions Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Glycolysis The NADH is an energy carrying molecule that holds the electrons (pair) until they can be transferred to other molecules. 2 ATP 2 ADP 4 ADP 4 ATP 2NAD+ 2 Pyruvic acid 2 To the electron transport chain Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Science 122 Sneak Preview: In many of the chemical reactions that are part of cellular respiration, the molecules involved are gaining or losing electrons: either receiving electrons from another molecule, or giving electrons to another molecule. When a substance loses electrons, we say is oxidized, and when a substance gains electrons, it is reduced. LEO the lion says GER Where “LEO” stands for “loss of electrons is oxidation” and “GER” stands for “gain of electrons is reduction.” Typically, in this type of chemical reaction, both reduction and oxidation will happen simultaneously because one molecule is losing electrons as it gives them to another molecule which, therefore, is gaining them. Because of that, chemists and biologists call these kinds of reactions redox reactions (“red-” from “reduction” and “ox” from “oxidation”). Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Glycolysis The Advantages of Glycolysis The process of glycolysis is so fast that cells can produce thousands of ATP molecules in a few milliseconds. Glycolysis does not require oxygen. Copyright Pearson Prentice Hall

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Copyright Pearson Prentice Hall Fermentation Fermentation When oxygen is not present, glycolysis is followed by a different pathway. The combined process of this pathway and glycolysis is called fermentation. Fermentation releases energy from food molecules by producing ATP in the absence of oxygen. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Fermentation Fermentation does not require oxygen—it is an anaerobic process. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Fermentation What are the two main types of fermentation? Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Fermentation The two main types of fermentation are lactic acid fermentation and alcoholic fermentation. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Fermentation Alcoholic Fermentation Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Fermentation Lactic Acid Fermentation In many cells, pyruvic acid that accumulates as a result of glycolysis can be converted to lactic acid. Copyright Pearson Prentice Hall

PYRUVIC ACID ___________ OXYGEN WITHOUT 2 kinds of fermentation ___________________ & _____________________ WITHOUT ANAEROBIC Alcoholic Lactic acid

ALCOHOLIC FERMENTATION Instead of going to ETC in cell respiration _______ +_____ →__________ + ______ + _____ PYRUVIC ACID ALCOHOL CO2 NAD+ Happens when yeast makes bread dough rise CO2 bubbles make _____________ in bread Alcohol _______________ during cooking air spaces evaporates http://www.deliciousdelicious.com/archives/herb%20bread%201.jpg

ALCOHOLIC FERMENTATION _______ +_____ →__________ + ______ + _____ PYRUVIC ACID ALCOHOL CO2 NAD+ Happens when ___________ make _______ or ____________ make ______ yeast beer bacteria wine http://www.firstpath.com/images/alcohol.jpg

LACTIC ACID FERMENTATION _______ +_____ →______________ + ________ PYRUVIC ACID LACTIC ACID NAD+ muscles Happens in _____________ during ____________when body can’t get oxygen to tissues fast enough. Lactic acid builds up in muscles causing soreness exercise http://www.miranda.com/library.en/Images/Pictures/girls-runners.jpg

LACTIC ACID FERMENTATION _______ +_____ →______________ + ________ PYRUVIC ACID LACTIC ACID NAD+ Happens when bacteria are used to make ___food_______and ____beverages____ like: Yogurt, buttermilk, sauerkraut, pickles, cheese sour cream, & kimchi http://chronicle.augusta.com/images/headlines/032200/DANNON_YOGURT.jpg http://www.reillydairy.com/natural_cheese.html

WHY DO FERMENTATION? WHY NOT JUST KEEP MAKING ATP USING GLYCOLYSIS? WITHOUT OXYGEN, PYRUVIC ACID ___________ and all the _______ carriers get full. Eventually glycolysis will builds up NAD+ NAD+

→ → FERMENTATION HAPPENS so cells can ____________________ PYRUVIC ACID _______ +_____ →__________ + ______ + _____ CO2 NAD+ ALCOHOL → NAD+ LACTIC ACID ______ → You get the NAD+ taxis back FERMENTATION HAPPENS so cells can ____________________ needed to keep glycolysis going REGENERATE the NAD+

Copyright Pearson Prentice Hall 9-1 Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 9-1 The raw materials required for cellular respiration are carbon dioxide and oxygen. glucose and water. glucose and oxygen. carbon dioxide and water. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 9-1 Glycolysis occurs in the mitochondria. cytoplasm. nucleus. chloroplasts. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 9-1 The net gain of ATP molecules after glycolysis is 3 ATP molecules. 2 ATP molecules. 3 pyruvic acid molecules. 4 pyruvic acid molecules Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 9-1 Fermentation releases energy from food molecules in the absence of oxygen. glucose. NADH. alcohol. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall 9-1 The first step in fermentation is always lactic acid production. the Krebs cycle. glycolysis. alcohol production. Copyright Pearson Prentice Hall

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