21 Exercise Physiology Final Exam Packet Chapters 5 7 8 pp 186 190 RER lab and lecture notes Bioenergetics 1 Differentiate between aerobic and anaerobic metabolism This refer to the two systems that the body uses to make energy or ATP Aerobic respiration means with oxygen and anaerobic means without oxygen but those terms aren t technically correct ATP production starts with glycolysis in the cell s cytosol The six carbon molecule is cleaved over many steps into two three carbon molecules called pyruvate This is known as anaerobic respiration since oxygen is nowhere in the equation At this point the pyruvate can form lactate to keep glycolysis running if ATP is needed fast during intense exercise or it can enter the cell s mitochondria Once it enters the mitochondria it is committed to aerobic respiration and it is known as such This process is very lengthy but produces much more energy than glycolysis alone Oxygen is the final electron receptor for this A better term for anaerobic is fast glycolysis since it supplies energy fast and is used when we need energy right away Aerobic is commonly called slow glycolysis since it takes a long time to utilized but provides much more energy 2 What is ATP How does it function How is it formed This is the main energy currency in the body Think of ATP as money that can be used to power your muscles ATP is an adenosine molecule one of the bases of DNA attached to three phosphates When one phosphate is cleaved energy is released during the cleavage One thing you will notice is everything in the body is controlled via adding a phosphate to something or So the body takes chemical energy in the form of ATP and transforms it into mechanical energy taking a phosphate off in the form of muscle contraction Tony Berardi 21 3 Describe glycolysis Know net ATP yield depending on substrate used glycogen or glucose and know what other energetic molecules are formed e g NADH H How is lactate formed during glycolysis What are the conditions under which it is formed This is the catabolic pathway that glucose enters to yield energy Just know that you start with glucose go through a whole bunch of reactions and end up with pyruvate Pyruvate can then go to two paths that I will explain later This process occurs in the cells cytosol Anaerobically glucose will become lactate Anaerobic mean without oxygen Aerobically it will become acetyl CoA Glycolysis only occurs in the CELL S CYTOSOL capitalized because it s probably important Through many steps the net ATP is only 2 If you want to learn all the steps two steps at the beginning actually use 1 ATP each so you have to put in an input to get an output of ATP After you put in 2 ATP you then make 4 ATP in the next steps but you only end up with a net of 2 ATP Glycogen is the storage form of glucose in the body the muscles combine many glucose molecules together as storage Free glucose is also circulating in your blood The difference in the maximum amount of ATP formed between them is based on the first step of glycolysis In the first step glucose is phosphorylated into glucose 6 phosphate and this takes one ATP This is so the glucose does not leave the cell Free glucose must take this step so the glucose does not leave the cell Since glycogen is already in the muscle the glucose simply has to break its storage and thus it will skip that step free glucose takes What does this mean That the total amount of ATP formed from glycogen will always be one more than free glucose So glycolysis will form 3 ATP if glycogen is used The potential for glucose metabolism to form ATP is in the form of the high energy molecules NADH2 and FADH2 These molecules carry electrons from hydrogen atoms and this electrons are what creates the majority of ATP in aerobic respiration in the electron transport chain So glycolysis takes the six carbon glucose and cleaves it into two three carbon pyruvates Now what Depending on how fast our muscles need ATP will determine what happens now If we need energy fast as in during intense exercise pyruvate will form lactate The reason for this is simple to form pyruvate the body had to use a NAD to form NADH has a lot of potential to form ATP so this means that NAD is required in order to form pyruvate and form the 2 ATP that glycolysis forms When you need energy fast this glycolysis has to keep running but the cell will run out of NAD fast When pyruvate forms lactate NADH only makes all it s ATP in the electron Tony Berardi 21 transport chain will turn back into NAD This will allow glycolysis to keep happening and thus form the 2 ATP Another reason of why we form lactate is because we are producing pyruvates much faster than the TCA cycle can use them in aerobic respiration So the pyruvate builds up and the pyruvate instead forms lactate because it is much faster and yields energy faster 4 Describe the krebs cycle Know what happens to pyruvate before entering the Krebs cycle Know what important high energy molecules are formed e g FADH NADH H ATP Now if energy is not required right away as in endurance exercise the pyruvates will enter another route Instead of forming lactate they will enter the cell s mitochondria Once it enters the mitochondria known as the powerhouse of the cell it has committed to aerobic respiration Once inside it will form acetyl coA along with a NADH this is irreversible As acetyl coA it will go through many reactions which release Co2 this is what we exhale and they will also form NADH and FADH2 along with a GTP Each cycle of the Krebs Cycle or TCA Cycle form 3 NADH 1 FADH2 and one GTP The formation of pyruvate to acteyl CoA forms 1 NADH So if we add it all up we have formed 4 NADH 1 FADH2 and 1 GTP but remember that we have two pyruvates so we double everything to give 8 NADH 2 FADH and 2 GTP All these molecules will makes since after the next step 5 Describe the ETC Know what the role of NADH H and FADH in the ETS and the differences in energy yield Know the general mechanism by which energy is produced in the ETS The next stop for all those NADH and FADH2 is the electron transport chain the GTP forms an ATP through a different reaction A simple understanding is all that is needed There are four complexes that make up the chain and each complex takes away electrons from the NADH and FADH The very last complex takes all the electrons and uses them to form an ATP molecule Oxygen is the final electron acceptor and this is why we need to breathe oxygen to live Think of the
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