Transcript Chapter 6
Respiration-- AKA “breathing” Most associate respiration with the intake of Oxygen and exhaling of Carbon Dioxide. It is much more complicated than that!! After Oxygen enters your bloodstream it combines with sugar from your food intake to make ATP for energy. A by-product of all this activity is Carbon Dioxide. Respiration is called an AEROBIC process since it requires Oxygen to take place. ATP In order for sugar to provide energy, it requires 3 steps: 1. Glycolysis– “splitting the sugar” -happens in the cytoplasm of the cell -6 Carbon glucose molecule is split into 2, 3 Carbon molecules called “pyruvates” -NAD+, an enzyme, picks up high energy electrons of hydrogen to take to the next stage. This forms NADH. - some ATP is also made in this step -The “pyruvates” continue into step 2. 2. The Krebs Cycle—happens inside the mitochondria --”fuel” in the form of pyruvic acid is modified for use and becomes Acetyl CoA. --the Acetyl CoA is completely broken down into Carbon Dioxide, ATP and enzymes NAD+ and FAD++ that become NADH and FADH2 --Carbon Dioxide becomes a by-product that you breath out during respiration. --The enzymes carry the high energy H+ into the next and final step. 3. The Electron Transport System or ETS– in the mitochondria cristae. -Enzymes drop off Hydrogen at the beginning of the ETS and then return to Glycolysis or Krebs for another H ion. -Oxygen is key ingredient in ETS FADH2 -it pulls the H down the cristae to the end of the chain. -H releases energy each time it jumps down the pump -end result is water and Lots of ATP energy Total energy output from Aerobic Respiration: Glycolysis…………………..2 ATP Kreb’s Cycle………………..2 ATP Electron Transport Chain…32 ATP Total...36 ATP (38) These numbers are only true of respiration when oxygen is present in the reaction. If no oxygen is present, the cell must use an alternate form of respiration: ANAEROBIC RESPIRATION or FERMENTATION Anaerobic Respiration cannot use the same 3 steps that aerobic respiration uses because no oxygen is present to run the ETS. Instead, anaerobic respiration relies on the first step, Glycolysis, to supply the cell with energy. Recall how many ATP are produced by the glycolysis process. Glycolysis…………………..2 ATP This is the Total Energy output for fermentation. Although energy production isn’t great, it is better than the alternative…nothing at all!!! Although fermentation seems like a simple process, it must be able to recycle the NADH in order to keep the process going. This is done by the pyruvic acid accepting the H+ ion to make by-products allowing the NAD+ to return for more H+. http://www.uic.edu/classes/bios/bios100/lectures/09_25a_fermentation-L.jpg Two types of by-products are produced, depending on the organism using the fermentation process: Lactic Acid—found in human muscles and microorganisms Ethyl Alcohol—found in yeast These by-products may provide benefits to society in the form of alcohol products, canning process benefits and production of yeasty bread products. http://1.bp.blogspot.com/KwCaCv69Gsk/T0vbrrfXQRI/AAAAAAAA Byk/S41salirjto/s1600/alcoholic_fermenta tion.jpg Lactic Acid build-up in human muscle cells causes muscle soreness after strenuous exercise. Think about what you do when you exercise (die is not a good answer here!!) You start out pretty good, then begin to breathe faster, then start to feel muscle fatigue, then run out of energy. Muscle cells are forced to revert to anaerobic respiration when Oxygen supplies cannot meet energy demand. This is what results in fatigue and soreness after exercise is attributed to lactic acid (a poison) build-up in muscle cells. How most of you would look! ---How your instructor would look!! --- Lactic acid is also produced by microorganisms in Oxygen free environments. --canning process produces anaerobic conditions --necessary to get “good” seal on cans or must eat food right away --correctly canned, food can last a long time --best canned foods are the oldest…lactic acid becomes a flavoring agent --build-up will eventually create high acid environment and Cheese is continually microorganisms cannot survive pressed and sealed to here create the anaerobic process necessary to --cheese and yogurt, olives and produce the different Kraut, soy sauce all employ flavors of cheese. The aging process also same process contributes to flavor. Soy sauce is fermented juice from the soybean. It cannot even be placed on the market shelf until it is at least one year old!! Kraut lovers of the world… Unite!!! Kraut is NOT rotten cabbage!! It is fermented cabbage and we love it!! Ethyl Alcohol is a by-product released during fermentation of sugar products by yeast cells. This process is economically important for several reasons: Bread relies on this process. Yeast “breaks down” the sugar and flour carbohydrates. The by-products released during the “rising” period help create fluffy bread. Which by-product besides ethyl alcohol is produced? What does it do? How can you eat bread and not become inebriated? The brewing industry also relies on yeast fermentation of carbohydrates. They use the sugar in grains and fruits to produce ethyl alcohol and carbon dioxide. Instead of “driving off” the alcohol, it is bottled and marketed. Beer is the result of yeast fermenting hops and different grain products. Different grains produce different flavors of light and dark brews. Wine and champagne are the result of fruit fermentation. Aging contributes greatly to the flavor of wines. Champagne bubbles come from the addition of Carbon dioxide. It is easy when talking about bread and brew making to forget the concept behind the process relies on no oxygen being present. What happens if oxygen is present in wine or brewing processes? How can you check and make sure sufficient anaerobic conditions are being met? What ingredients would you consider essential if you wanted to make your own brew or wine? Saccromyeces cerivasae “brewers yeast”, an facultative anaerobe Humans tend to be obligate aerobes because we depend so much on oxygen. E. aerogenes, a obligate anerobe.