Chapter 9-2 Out Line for Biology

9–2 The Krebs Cycle and Electron Transport (p. 226-232)

How much of the energy that is available in glucose, has been used/released by the end of glycolysis? Only about 10%. To get the rest of the energy released, what powerful electron acceptor does a cell use? oxygen Define aerobic: refers to a process that requires oxygen

Look up and define anerobic: refers to a process that is ‘not in air’ or does not require oxygen Cellular respiration specifically refers to : energy-releasing pathways that occur within a cells mitochondria ….while respiration usually just means: the act of breathing A. The Krebs Cycle - What is it? The second stage of cellular respiration that occurs if oxygen is present What happens during the Krebs Cycle? (Key Concept): During Krebs Cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions. What is its other name? citric acid cycle Why? Because citric acid (citrate) is the first compound formed in this series of reactions Where does it take place? In the mitochondrial matrix On Figure 9-6 below, show the three places where carbon dioxide is produced, by circling them in red. How does the carbon dioxide produced leave an organism? When the organism exhales

What 2 electron carriers receive electrons, and most of the chemical energy in Krebs Cycle? NAD+ and FAD+ Show where they are on Fig. 9-6 by boxing them in yellow. What do they become? 4 NADHs and 1 FADH2 How may ATP are generated from every turn of the Krebs Cycle? just one

B. Electron Transport – What is it? The movement of the high energy electrons generated in the Krebs Cycle that move in a series of proteins embedded in the inner mito. membrane How are high-energy electrons used by the Electron Transport Chain?(Key Concept): The electron transport chain uses high energy electrons from the Krebs Cycle to convert ADP into ATP. Where does it take place? in the inner mitochondrial membrane What happens that causes NADH to change to NAD+, and FADH2 to change to FAD? The electron carriers give up their high-energy electrons to the carrier proteins on the electron transport chain What happens to those electrons? They are passed from one carrier protein to the next Where does the energy come from that moves hydrogen ions into the intermembrane space? The energy comes from the electrons moving down the electron transport chain. What is the role of ATP synthase in cellular respiration? ATP synthase (an enzyme) uses energy from H+ ions to convert ADP into ATP. Include how the difference in charge on either side of the membrane is used to produce ATP molecules. During electron transport, H+ ions build up in the intermembrane space, making it + charged. The other side of the membrane, from which those H+ ions have been taken, is now – charged.

C. The Totals How much chemical energy does cellular respiration yield from one molecule of glucose? 36 ATP molecules Compare how much is generated with or without oxygen present. Without oxygen, during glycolysis, only 2 ATP, but 34 more, for a total of 36, if oxygen is present and the pyruvic acid travels into the Krebs Cycle. What happens to the energy from glucose that your body doesn’t make into ATP? It is released as heat….like when you exercise, or leave behind heat on the surfaces that you touch. D. Energy and Exercise- When runners/swimmers begin a race, how do their bodies obtain energy? They first use the energy in their muscles, then the ATP made by lactic acid then by cellular respiration 1.Quick Energy –from where do your cells get quick energy? By lactic acid fermentation 2.Long-Term Energy- write about the role of glycogen. Glycogen is a carbohydrate that can store energy for 15-20 minutes of activity, after that you body will use other stored energy, such as that in fat. Why do runners breathe heavily after a race? To get oxygen to make up for all they lost- it is how they get rid of the lactic acid that builds up in their muscles.

a. Comparing Photosynthesis Cellular Respiration
|Function |energy capture |Energy release |
|Location |chloroplasts |mitochondria |

(use chart on pg. 232) The energy flows in photosynthesis and cellular respiration take place in opposite directions. Label the equations below, and write ‘product’ and ‘reactant’ underneath the respective components. PHOTOSYNTHESIS [pic] CELLULAR RESPIRATION

Reactants products [pic]

Figure 9-6 The Krebs Cycle (pg 227). Write the Key Concept here: During the Krebs Cycle, pyruvic acid (3 carbon) from glycolysis is used to make carbon dioxide (1 carbon) , NADH, ATP, and FADH2.

[pic]

Figure 9-7 Electron Transport Chain (pg 228), Write the Key Concept here: The electron transport chain (ETC) uses high energy electrons from the Krebs Cycle to convert ADP into ATP. Label the figure below to include A, B, and C, as well as the location indicated by the brackets.

[pic]

Inter membrane Space InnerMemrane Matrix