End Show Slide 1 of 39 Copyright Pearson Prentice Hall Biology

End Show Slide 2 of 39 Copyright Pearson Prentice Hall 9-1 Chemical Pathways

End Show Slide 3 of Chemical Pathways 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 Plant Animal Cells Plant Cells Mitochondrion

End Show Slide 4 of Chemical Pathways Copyright Pearson Prentice Hall Both plant and animal cells carry out the final stages of cellular respiration in the mitochondria. Animal Cells Plant Cells Mitochondrion Outer membrane Intermembrane space Inner membrane Matrix

End Show Slide 5 of Chemical Pathways Copyright Pearson Prentice Hall Chemical Energy and Food One gram of the sugar glucose (C 6 H 12 O 6 ), 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.

End Show Slide 6 of Chemical Pathways 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.

End Show Slide 7 of Chemical Pathways 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.

End Show 9-1 Chemical Pathways Slide 8 of 39 Copyright Pearson Prentice Hall Overview of Cellular Respiration What is cellular respiration?

End Show Slide 9 of Chemical Pathways Copyright Pearson Prentice Hall Overview of Cellular Respiration Cytoplasm Pyruvic acid Mitochondrion Electrons carried in NADH Electrons carried in NADH and FADH 2 Glucose Glycolysis

End Show 9-1 Chemical Pathways Slide 10 of 39 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.

End Show Slide 11 of Chemical Pathways Copyright Pearson Prentice Hall Overview of Cellular Respiration The equation for cellular respiration is: 6O 2 + C 6 H 12 O 6 → 6CO 2 + 6H 2 O + Energy oxygen + glucose → carbon dioxide + water + Energy

End Show Slide 12 of Chemical Pathways 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.

End Show Slide 13 of Chemical Pathways 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. Cytoplasm Mitochondrion Glycolysis

End Show 9-1 Chemical Pathways Slide 14 of 39 Copyright Pearson Prentice Hall Glycolysis What happens during the process of glycolysis?

End Show Slide 15 of Chemical Pathways Copyright Pearson Prentice Hall 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.

End Show Slide 16 of Chemical Pathways 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 ADP 4 ADP 4 ATP 2 Pyruvic Acid 2 ATP Glucose

End Show Slide 17 of Chemical Pathways 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 ADP 4 ADP 4 ATP 2 ATP Glucose 2 Pyruvic acid

End Show Slide 18 of Chemical Pathways Copyright Pearson Prentice Hall Glycolysis This gives the cell a net gain of 2 ATP molecules. 4 ADP 4 ATP Glucose 2 ADP 2 ATP 2 Pyruvic acid

End Show Slide 19 of Chemical Pathways 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 Glucose 2 Pyruvic acid 4 ADP 4 ATP 2 ADP 2 ATP Glucose is oxidized…loses electrons in chemical reactions

End Show Slide 20 of Chemical Pathways 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. To the electron transport chain 2NAD + 2 Pyruvic acid 4 ADP 4 ATP 2 ADP 2 ATP 2

End Show Slide 21 of Chemical Pathways Copyright Pearson Prentice Hall 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”). Science 122 Sneak Preview:

End Show Slide 22 of Chemical Pathways 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.

End Show Slide 23 of Chemical Pathways Copyright Pearson Prentice Hall 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.

End Show Slide 24 of Chemical Pathways Copyright Pearson Prentice Hall Fermentation Fermentation does not require oxygen—it is an anaerobic process.

End Show 9-1 Chemical Pathways Slide 25 of 39 Copyright Pearson Prentice Hall Fermentation What are the two main types of fermentation?

End Show Slide 26 of Chemical Pathways Copyright Pearson Prentice Hall Fermentation The two main types of fermentation are lactic acid fermentation and alcoholic fermentation.

End Show Slide 27 of Chemical Pathways Copyright Pearson Prentice Hall Fermentation Alcoholic Fermentation Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes.

End Show Slide 28 of Chemical Pathways 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.

End Show Slide 29 of Chemical Pathways PYRUVIC ACID ___________ OXYGEN 2 kinds of fermentation ___________________ & _____________________ ANAEROBIC Alcoholic Lactic acid WITHOUT

End Show Slide 30 of Chemical Pathways _______ + _____ → __________ + ______ + _____ ALCOHOLIC FERMENTATION PYRUVIC ACID ALCOHOL Happens when yeast makes bread dough rise CO 2 bubbles make _____________ in bread Alcohol _______________ during cooking CO 2 NAD + air spaces evaporates Instead of going to ETC in cell respiration….b/c no Oxygen is present…sooo…

End Show Slide 31 of Chemical Pathways _______ + _____ → __________ + ______ + _____ ALCOHOLIC FERMENTATION PYRUVIC ACID ALCOHOL Happens when ___________ make _______ or ____________ make ______ CO 2 NAD + yeast beer bacteriawine

End Show Slide 32 of Chemical Pathways _______ + _____ → ______________ + ________ LACTIC ACID FERMENTATION PYRUVIC ACID LACTIC ACID Happens in _____________ during ____________when body can’t get oxygen to tissues fast enough. Lactic acid builds up in muscles causing soreness NAD + exercise muscles

End Show Slide 33 of Chemical Pathways _______ + _____ → ______________ + ________ LACTIC ACID FERMENTATION PYRUVIC ACID LACTIC ACID Happens when bacteria are used to make ___food_______and ____beverages____ like: Yogurt, buttermilk, sauerkraut, pickles, cheese sour cream, & kimchi NAD +

End Show Slide 34 of Chemical Pathways WITHOUT OXYGEN, PYRUVIC ACID ___________ and all the _______ carriers get full. Eventually glycolysis will WHY DO FERMENTATION? WHY NOT JUST KEEP MAKING ATP USING GLYCOLYSIS? builds up NAD +

End Show Slide 35 of Chemical Pathways _______ + _____ → __________ + ______ + _____ FERMENTATION HAPPENS so cells can ____________________ needed to keep glycolysis going PYRUVIC ACID ALCOHOL → CO 2 NAD + REGENERATE the NAD + LACTIC ACID NAD + → You get the NAD + taxis back ______

End Show - or - Continue to: Click to Launch: Slide 36 of 39 Copyright Pearson Prentice Hall 9-1

End Show Slide 37 of 39 Copyright Pearson Prentice Hall 9-1 The raw materials required for cellular respiration are a.carbon dioxide and oxygen. b.glucose and water. c.glucose and oxygen. d.carbon dioxide and water.

End Show Slide 38 of 39 Copyright Pearson Prentice Hall 9-1 Glycolysis occurs in the a.mitochondria. b.cytoplasm. c.nucleus. d.chloroplasts.

End Show Slide 39 of 39 Copyright Pearson Prentice Hall 9-1 The net gain of ATP molecules after glycolysis is a.3 ATP molecules. b.2 ATP molecules. c.3 pyruvic acid molecules. d.4 pyruvic acid molecules

End Show Slide 40 of 39 Copyright Pearson Prentice Hall 9-1 Fermentation releases energy from food molecules in the absence of a.oxygen. b.glucose. c.NADH. d.alcohol.

End Show Slide 41 of 39 Copyright Pearson Prentice Hall 9-1 The first step in fermentation is always a.lactic acid production. b.the Krebs cycle. c.glycolysis. d.alcohol production.

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