BIOL 101 Guided Reading Questions GRQs Complete and submit this GRQ as a PDF before lecture and before your online Mastering Assignment L7 GRQs Cellular Respiration Reading 6 6 6 14 Note this content can be dense at times Follow the questions as you usually do to see my expectations for where you should be spending your time Tip Watch the BioFlix in the Study Area of Mastering Put it on mute can narrate it Reading Objectives Describe the inputs and outputs of each three stages of aerobic respiration and compare each stage for amount of ATP made and location in the cell Explain why oxygen is necessary and what happens when oxygen is not available Explain why lactic acid or ethyl alcohol is sometimes an output of cellular respiration REVIEW Module 6 6 Overview Cellular Respiration occurs in three main stages What are the names of the three stages and where does each stage take place Quick description of what happens Name Stage 1 Glycolysis Location in cell it occurs Cytosol Breaks glucose down into two molecules of a three carbon compound called pyruvate The complete breakdown of glucose to carbon dioxide Stage 2 Pyruvate Mitochondria oxidation and Citric acid cycle Stage 3 Oxidative phosphorylation Inner mitochondrial membrane Electron transport and chemiosmosis Look at image 6 6 in your book and describe it THEN see if you can fill it in Test yourself as you complete it don t just copy directly stress learning over memorization What the little blue circles where do they come from and where do they go What are the yellow starbursts Module 6 7 Stage 1 Glycolysis harvests chemical energy by oxidizing glucose to pyruvate 1 What is substrate level phosphorylation and how many ATP form in glycolysis by this Substrate level phosphorylation is the process where an enzyme transfers a phosphate group from a substrate molecule to ADP forming ATP 2 How many pyruvates form in glycolysis 2 Each pyruvate has how many carbons 3 3 Electrons are passed to NAD which is reduced to become NADH 4 How many NADH form from glycolysis 2 These will hold shuttle electrons to the third stage Module 6 9 Stage 2 The Citric Acid Cycle completes the energy yielding oxidation of organic molecules 1 What three mini steps occur as each pyruvate is groomed before the citric acid cycle CO2 NADH Acetyl CoA 2 Pyruvate loses a carbon which is released in the form of carbon dioxide 3 Electrons reduce NAD to form NADH 4 A coenzyme called Coenzyme A joins the two carbon compound to form Acetyl CoA 5 As a two carbon acetyl coA enters the citric acid cycle a series of reactions begin Ultimately the two carbons are released in the form of carbon dioxide 6 Electrons from the intermediate reactions are reduced NAD to form how many NADH 3 7 FAD is also reduced to form one FADH2 Substrate level phosphorylation forms 1 ATP Remember that we split glucose into two pyruvates so everything you see in Fig 6 9 would be doubled Skip Module 6 10 feel free to look at it if you are interested Module 6 11 Stage 3 Most ATP production occurs by Oxidative Phosphorylation 1 Stages 1 and 2 only produced a total net gain of 4 ATP per glucose molecule so far A total of 32 can be made 2 Electron transport proteins electron carriers and ATP synthase are located where The inner membrane of the mitochondrion 3 Follow the electrons in the figure in Module 6 11 as NADH and FADH2 are oxidized What ultimately happens to those electrons Follow the yellow arrows The electron carrying molecules become oxidized and the electrons travel to meet O2 the final oxygen receptor to form water 4 Besides passing electrons to each other through an electron transport chain what else do these proteins do Follow green arrows These proteins pump hydrogen ions into the inter membrane space The electron carried in the chain releases energy which enables the active transport of the hydrogen ions 5 Describe the significance of the gradient of H How do the H relate to ATP formation Be sure to use the words chemiosmosis and ATP synthase in your answer Hydrogen ions are transported from the mitochondrial matrix to the inter membrane space through transport proteins The electron carriers become oxidized at the same time which supplies the energy needed to perform the active transport The resulting concentration gradients drive hydrogen ions through the enzyme complex ATP synthase through a process called chemiosmosis The molecular structure of ATP synthase enables the synthesis of large amounts of ATP Module 6 12 Scientists have discovered heat producing calorie burning brown fat in adults 1 Cellular respiration captures about 34 of the energy in glucose in ATP What happens to the rest of the energy not captured The rest of the energy is lost as heat 2 Brown fat burns fuel and produces heat but does not produce ATP As we would expect during cellular respiration 3 Explain why brown fat does not make ATP by explaining what part of stage 3 hint oxidative phosphorylation is different in brown fat Ion channels spanning the inner mitochondrial membrane that allow H to flow freely across the membrane Such channels would dissipate the H gradient that the electron transport chain had produced Without the gradient ATP synthase could not make ATP and all the energy from the burning of fuel molecules would be released as heat The mitochondria of brown fat cells have such channels 4 Up until recently we thought only human infants had brown fat 5 What did the PET scans tell the scientists about the presence of brown fat in adult males In adult females 7 5 in women and 3 in men 6 Practice analyzing data True or false Lean people BMI less than 25 have more brown fat than overweight people after exposure to cold weather True Module 6 13 Each molecules of glucose yields many molecules of ATP 1 How much ATP is gained from one glucose molecule during a Glycolysis 2 b Citric Acid Cycle 2 c Oxidative phosphorylation approximately 2 2 What stage produces carbon dioxide 2 3 What stage requires oxygen 3 4 What stage produces water 3 5 Glucose is oxidized during this process oxidized or reduced 6 Why do our muscle cells sometimes use lactic acid fermentation They cannot get O2 to your muscle cells 7 What is regenerated during the process that can then be used again for glycolysis NAD Module 6 14 Fermentation enables cells to produce ATP without oxygen 1 Fill in the blanks Fermentation Pathways Anaerobic Anaerobic pathways operate when oxygen is absent or limited Glycolysis is the first stage to yield 2
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