Cellular Respiration Do these before the Mastering Assignment Guided Reading Qs Reading 6 7 6 14 Note this chapter 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 animation in the Study Area of Mastering in this chapter Then put it on mute and see if you 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 1 Stage 1 Glycolysis We will be sticking to overviews i e I am interested in you knowing fig 6 7 A and B but NOT 6 7C Fig 6 7A is a simplification because there are actually nine reactions all performed by various enzymes represented by the arrow What is substrate level phosphorylation and how many ATP form in glycolysis by this Substrate level phosphorylation is the process of forming ATP by direct transfer of a phosphate group by an enzyme to and ADP from an organic molecule 2 ATP are formed in this process How many pyruvates form in glycolysis Two molecules 4 but 2 are used in the process Each pyruvate has how many carbons 3 Electrons are passed to pyruvate from glucose which is reduced to become NADH How many NADH form from glycolysis Two These will hold shuttle electrons to the third stage 2 Stage 2 Pyruvate Oxidation and Citric Acid Cycle What three mini steps occur as each pyruvate is groomed before the citric acid cycle 1 Pyruvate loses a carbon which is released in the form of CO2 2 Electrons reduce NAD to form NADH 3 A coenzyme called coenzyme A joins the two carbon compound to form Acetyl coenzyme A Acetyl CoA 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 CO2 Electrons from the intermediate reactions are reduced NAD to form how many NADH three FAD is also reduced to form one FADH2 Substrate level phosphorylation forms 2 ATP Remember that we split glucose into two pyruvates so everything you see in Fig 6 8 and 6 9A would be doubled Don t worry about Figure 6 9B 3 Stage 3 Oxidative Phosphorylation 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 Electron transport proteins electron carriers and ATP synthase are located where Inner membrane of the mitochandria 1 Follow the electrons in Fig 6 9 as they are oxidized from NADH and FADH2 What ultimately happens to those electrons They are ultimately reduced once again by NADH and FADH2 Besides passing electrons to each other through an electron transport chain what else do these proteins do Follow green arrows They pump H across the membrane 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 In the process of chemiosmosis the concentration gradient drives H through ATP synthase which is the enzyme complex that phosphorylates ADP to ATP This is crucial for forming ATP 4 Scientific Thinking 6 12 What is the difference in terms of metabolic activity and organelles between white fat and brown fat White fat has little metabolic activity while brown fat has high metabolic activity The mitochondria of brown fat have ion channels throughout the inner mitochondrial membrane that allow H to flow freely while white fat cells do not Brown fat burns fuel and produces heat but does not produce ATP As we would expect during cellular respiration Up until recently we thought only human infants had brown fat What did the PET scans tell the scientists about the presence of brown fat in adult males In adult females 7 5 of women and 3 of men have deposits of brown fat True or false Explain your answers Brown fat is activated to become metabolically active in hot weather False brown fat is activated by cold temperatures Lean people BMI less than 25 have more brown fat than overweight people True the brown fat activity of the lean group was greater than the overweight obese group How might this new information be applied to weight loss It indicates that for people with brown fat present in their bodies and it is activated by the cold more calories can be burned leading to more weight loss 5 How much ATP is gained from one glucose molecule during a Glycolysis 2 b Citric Acid Cycle 2 c Oxidative phosphorylation about 28 presence of these poisons Explain Some poisons block oxidative phosphorylation yet a small amount of ATP can be made in the Some cells can oxidize organic fuel and generate ATP without oxygen through fermentation which uses the pathway of glycolysis similar to the first stage of cellular respiration 2 6 Fill in the blanks Fermentation Pathways Anaerobic Anaerobic pathways operate when oxygen is absent or limited Glycolysis is the first stage to yield 2 ATP 2 pyruvate and 2 NADH In the absence of oxygen the reduced coenzyme used in glycolysis NAD cannot donate its electrons to the electron transfer chain Once it is oxidized we call it NADH 7 Why do our muscle cells sometimes use lactic acid fermentation To regenerate NAD when the need for ATP is greater than the amount of O2 inn the bloodstream What is regenerated during the process that can then be used again for glycolysis NAD 8 Examine fig 6 14A and B What are the differences between lactic acid fermentation and alcohol fermentation Lactic Acid fermentation produces 2 lactates while alcohol fermentation produces 2 ethanol and 2 CO2 What do you think you would need to make beer wine Alcohol fermentation 9 Without digging into any details of Modules 6 16 use figure 6 16 to explain why food with components other than glucose can be resources for making ATP For example how do proteins and fats make ATP Fats can become glycerol and fatty acids used in the process of glycolysis and the citric acid cycle Fats have many hydrogen atoms with many energy rich electrons Proteins can become amino acids that are also used in these processes For example glycogen from the liver and muscle cells can be hydrolyzed to glucose 3
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