Experimental view of Respiration

1. Experimental view of Respiration It is really quite simple… Breath in.. And breath out.. And let your cells do the work

2. Once upon a time • Once in a classroom far far away.. students used to mutter… • Oh why me? • Why do I have to learn this stuff and forr what reason?

3. So what is the basic task? • Lets start off with the basics. The purpose of cellular respiration is to create a form of energy useable by the cell. • This energy is created in the form of ATP (adenosine triphosphate). • Cellular respiration can be split up into four sequences. • -Glycolysis • -Transition Reactions • -Krebs Cycle or Citric Cycle • -Electron Transport Chain

4. Structure of mitochondria • The inner membrane is folded, each fold is called a crista (plural cristae) to increase its surface area for proteins that make-up the electron-transport chain (ETC) and ATP synthase. • Electrons (electricity!) flowing through the ETC powers the ATP synthase. • Cristae may have the appearance of plate-like folds, or tubular/finger-like projections with a round or angular cross-section, depending on cell-type and organism species.

5. Chemical pieces of the puzzle • To make a puzzle start with the corners. • Start to see the pattern… • How many ways are there to convert sugar into atp?

6. Global view of respiration • So..is respiration just about converting sugar to atp? • What is a common element in all of the reactions?

7. Another view • So..lets keep track of some key players… • Glucose • ATP • Carbon Dioxide • Oxygen • And processes..aerobic and anaerobic

8. Magic Number three • Number One • Glycolysis • Number Two • TCA cycle • Number Three • Oxidative Phosporylation

9. Glycolysis • Note: the net production of glycolysis from one molecule of glucose is:2 molecules of ATP (4 produced, 2 consumed) • 2 molecules of reduced NADH ( more accurately 2NADH + 2H+ )

10. Why Glycolysis • Glycolysis- • All in all the purpose of glycolysis is to break down one molecule glucose into two molecules of pyruvate. • The pyruvate molecules are than individually sent to the transition reactions. • Glycolysis has two Products, H20 and NADH. • Overall Glycolysis makes four ATP but its net gain is two ATP due to the fact that it uses two ATP in the process. • How can you break sugar down into small pieces without losing a lot of • Water • Energy

11. Glycolysis 1..or perhaps a simplified explaination • Glycolysis is a series of endothermic reactions (requires an input of energy).  • For glycolysis to start you need ATP. • This ATP gives one of its Phosphates (from the three is has) to Glucose. Now the ATP is ADP (di-phosphate). • Now the molecule of glucose is Fructose-6-phosphate.(a molecule of glucose with a phosphate on its 6th carbon). • Another ATP gives one of its phosphates to fructose-6-phosphate. the fructose is now fructose-1,6-phosphate. (it now has a phosphate on its first carbon as well). • Now this molecule is unstable so it splits into two smaller molecules of PGAL.

12. Glycolysis 2 …the next steps • Glycolysis 2- Glycolysis 2 is just the rest of glycolysis. • Glycolysis 2 is a series of exothermic reactions( give of thermal energy). The PGAL from glycolysis 1 is now broken down and NAD+ comes in to get the H+ ions. NAD is now reduced or stabilized in the form of NADH. PGAL can now take a phosphate from the cytosol to form PGAP (1,3 diphosphoglicerate). Two of these are formed for each molecule of glucose that enters glycolysis. • Now with the help of enzymes 2 ADP can come in and take 2 phosphates from the 2 PGAP. This makes the PGAP turn into PGA (3-phosphoglicerate). Now since two molecules of ATP were broken down and two molecules of ATP were made the net gain is zero ATP. • The Two molecules of PGA are now broken down releasing two water molecules making the PGA now PEP (phospheonolpyruvate). Finally another substrate level phosphorylation occurs. Two molecules of ADP come and each take a phosphate from PEP releasing two ATP and turning the PEP into Pyruvate. • The overall amount of ATP made was four, but since two of them were used the net gain was two ATP.      

13. Link from Glycolysis to TCA • Transition Reactions- The purpose of the transition reactions is to take two hydrogen electrons and one carbon dioxide away from the pyruvate and add a coenzyme called Coenzyme A. The new acetyl Co-A is ready to be sent to the Krebs Cycle. • All matter is held together by.. • “electron glue”

14. Mitochondria detailed • Why all these structure?

15. Aerobic Respiration • Aerobic respiration is preferred as it yields more ATP and hence more energy. When an athlete sprints fast or lifts a heavy weight, the muscles are working to hard and too quickly for the usual aerobic respiration involving the mitochondria to produce ATP fast enough.

16. Forms of Anaerobic Respiration • Creatine phosphate system:Instead the muscles rely upon glycolysis WITHOUT the TCA cycle and oxidative phosphorylation, as glycolysis alone does NOT require oxygen! • This results in a low ATP yield, however muscles have another store of energy which replenishes ATP – creatine phosphate. • There is enough creatine phosphate to replenish ATP levels for about 5 to10 seconds of intense anaerobic exercise. • Lactic acid system:If a sprinter is to run further, say 400 metres in about one minute, then both the ATP and the creatine phosphate stores in the muscles will be depleted – • the muscle must make more ATP! However, aerobic respiration is too slow, as it relies on the transport of oxygen from the air into the lungs and into the bloodstream to the cells! • Most of the energy required is still obtained by anaerobic respiration by the lactic acid pathway

17. Big wheel keeps on turning • Krebs Cycle- • The purpose of the Krebs Cycle is basically to produce NADH+H and FADH2. • Pyruvate enters the Krebs Cycle than goes through a series of reactions • The final product is six NADH+H and two FADH2. • These energy carriers are than sent to the electron transport chain. • The Krebs cycle  Goes around twice for every molecule of acetyl Co-A.

18. Within the Mitochondria

19. Transition reaction..simplified • Transition Reactions Simplified- • Ok. Now were in the inside of the mitochondria or more specifically the matrix. This stage of aerobic respiration only takes place if there is oxygen present. • If there is no oxygen present than fermentation takes place and you end up getting a build up of lactic acid.  • Pyruvate has to enter the matrix and does so with the help of a protein. Once inside of the matrix an enzyme prepares the pyruvate to be broken down and a molecule of NAD+ takes two electrons from it. • When this happens it releases a CO2.(which is why we exhale CO2) starting to get the picture yet? • The pyruvate is now a 2 carbon molecule called Acetyl. Acetyl immediately bonds with a coenzyme called Acetyl Co-A. Acetyl Co-A is than sent to the krebs Cycle.

20. Citric Acid Cycle • Once upon a time..all this had to remain in your brain…

21. Kreb Cycle Simplified • Krebs Cycle simplified - The Krebs Cycle is named after its founder Hans Krebs. • The first reaction uses an enzyme to remove the acetyl from Acetyl from Acetyl Co-A. This new two carbon molecule can now bond with a four carbon molecule called oxalacetate. • This new molecule has six carbons and is called citrate. An isometric conversion takes place and isocitrate forms. From there CO2 is released and NAD picks of a H+ ion. • Now the isocitrate has become ketoglutarate. Another CO2 is released from the ketoglutarate, this frees an H+ ion which bonds with a NAD ion making another NADH. • The Co-A is now replaced with a phosphate from the matrix now forming Succinyl Co-A and an ADP is bonded with a phosphate to make ATP creating succinate. Fad comes in and takes a H+ ion and becomes FADH2. • In doing so succinate turns into Fumarate. Now H20 is added to Fumarate to form Malate. Now another NAD is reduced and Oxalacetate if reformed! Now your ready to start the Krebs Cycle all over again.

22. ETC…or the “A” train • Electron Transport Chain- • The purpose of the electron transport chain is to make the majority of ATP created in cellular respiration. • The NADH and FADH2 from the Krebs Cycle drop their electrons at the starting of the electron transport chain. • As the electrons move along the electron transport chain they give it power to pump hydrogen across the membrane from the matrix into the intermediate space. • This creates a concentration gradient forcing the hydrogen through ATP synthase bounding ADP with Pi ( inorganic Phosphate). • As the electrons move along the transport chain they lose their energy and at the end are picked up by oxygen and bonding with hydrogen making the bi-product H20.

23. Electron Transport Chain • So ..how many limiting factors can you see? • What is the role of a concentrations gradient?

24. ETC…simplified • Chimiosmosis Electron Transport Chain Simplified- • Chimiosmosis is simply the movement of hydrogen across the membrane. • This is probably the most easy part of cellular respiration (to understand that is). The NADH and FADH2 from the Krebs Cycle transport their H+ electrons to the electron transport chain. • The electron transport chain oxidizes or breaks down the NADH and FADH2 giving the chain electrons and in doing so release their H+ ions. The electrons given to the chain travel through and energize the proton pumps so that they can pump the H+ ions across from the matrix into the space between the inner and outer membrane of the mitochondria. • By the time the electrons get to the end of the chain the are very low on energy so an oxygen picks them up and two hydrogens are attached to it making a water molecule (H2O). Mean while the electrons being pumped across the membrane are creating a concentration gradient in the enclosed space. • This is  like air in a balloon, it wants to escape and soon as it finds a hole it will. In this situation the hole is ATP synthase. • As the hydrogen ions flow back into the matrix through ATP synthase they charge ATP synthase giving it the energy to bond ADP with a Phosphate making ATP. This is where the majority of ATP is made in cellular respiration. (32/34 ATP are made in the electron transport chain) 

25. Oxidative Phosporylation • ATP synthase (stalked particles) are proteins that release energy from glucose/fats using energy from flowing electric charges – glucose is oxidised to release electrons and H+. The flow of the electrons through the ETC pumps H+ into the inter-membrane space. The H+ then flow through the ATP synthase, back into the matrix, releasing energy that is used to make ATP. This is aerobic respiration.

26. So..making a comparison • From the three processes what are factors that increase the rate of respiration • What is the role of Oxygen? • What is the role of Water? • What is the role of membranes? • From the three processes, what are factors that could decrease the rate of respiration • What is the role of Carbon dioxide • What regulated Phosporylation? • What is the role of Calcium phospate?

27. Measuring Respiration • Now… • We need to create an experimental design to show how this all works!

28. References • http://shortie894.tripod.com/index.html • http://www.google.com/imgres?q=cell+respiration&um=1&hl=en&biw=1889&bih=968&tbm=isch&tbnid=sLeYplg-l4DmrM:&imgrefurl=http://lc.brooklyn.cuny.edu/smarttutor/corc1321/energy.html&docid=RIwGhw9cjxnDTM&imgurl=http://lc.brooklyn.cuny.edu/smarttutor/corc1321/images/energy/b.aerobic.jpg&w=449&h=434&ei=p1GTUKXME6GyigL2q4DQCA&zoom=1&iact=hc&vpx=710&vpy=248&dur=8461&hovh=221&hovw=228&tx=114&ty=92&sig=113956239353981504449&page=2&tbnh=147&tbnw=153&start=46&ndsp=56&ved=1t:429,i:341 • Music and videos! • http://www.youtube.com/watch?v=VCpNk92uswY • http://www.youtube.com/watch?v=1TGg6KyOwc0