Transcript Slide 1
Cellular Respiration • Cellular respiration is the process by which all organisms break down the food they consume or create. • The mitochondria break down food to produce ATP in the cellular respiration process. (Powerhouse) Chemical Rxn of Respiration 6O2 + C6H12O6 6H2O + 6CO2 + Energy (36 ATP) Notice it is the opposite rxn of photosynthesis!!! • 3 Stages of Cellular Respiration – 1. Glycolysis – Anaerobic – No oxygen needed – If there is oxygen, continues to the step 2 & 3. – If there is no oxygen, fermentation. – 2. Citric Acid Cycle – Aerobic – Need Oxygen – 3. Electron Transport Chain – Aerobic – Need Oxygen 1st Step: Glycolysis • “the splitting of glucose” • All respiration processes begin here. • Takes place in the cytoplasm. • 2 molecules of ATP break glucose down into Pyruvic Acid and release 4 molecules of ATP. (Have to put in ATP to get more out.) • If no O fermentation Final products of Glycolysis (per one glucose) • 2 Pyruvic acids – Krebs Cycle • 2 NADH – holds e- until Electron Tran Chain • 2 ATP • Aerobic Res. produces a much larger amount of ATP than fermentation, up to 20 times more ATP produced Fermentation: Anaerobic Respiration • This is the next step, ONLY if no oxygen is present. • Fermentation does produce ATP, but only a small amount. (2) • Pyruvic Acid produces Lactic Acid or ethynol. 2 Types of Fermentation • 1. Lactic Acid Fermentation: (muscle pain) – Happens in fatigues muscle cells during periods of strenuous exercise. The build up of lactic acid causes a burning pain. • 2. Alcoholic Fermentation – Yeast and some bacteria can break down sugar to produce ethanol, carbon dioxide, and energy – Makes bread rise, alcoholic beverages, gasoline, yogurt, cheese. http://biology.clc.uc.edu/fankhauser /cheese/CHEESE.HTML • Dr. Fankhauser has a number of fermentation-related recipes online, complete with photographs: • His main cheese page http://biology.clc.uc.edu/fankhauser/cheese/CHEESE.HTML Step 2: Krebs Cycle or Citric Acid Cycle • Similar to the Calvin Cycle. • After Glycolysis, the Pyruvic acid molecules move into the mito for further breakdown. • Krebs is a biochemical pathway that breaks down pyruvic acid, to make acetyl Co A, then making 1 ATP, H ions, and 3CO2, 4 NADH, 1FADH2. Continue Krebs Cycle • In Prokaryotes – Krebs occurs in cell membrane. • In Eukaryotes – Krebs occurs in the inner membrane of mitochondria. (matrix, more surface area) Final Products of 2 turns of the Krebs Cycle from 2 pyruvic acids So goes around 2 times!! • • • • 2 ATP 8 NADH 2 FADH2 6 CO2 Step 3: Electron Transport Chain • Takes place in the inner membrane of the mitochondria. • Carrier proteins (blue) • The ETC creates a high vs. low concentration allowing the ATP Synthase to begin working. Creating tons of ATP. • For every pair of e- in the ETC = 3 ATP Why do we need the Oxygen • Oxygen serves as the final e- acceptor on the ETC. • Oxygen gets rid of low energy e- and H+ ions, the wastes of cellular res. ETC Final Product • 32 ATP • Much more than any other cycle or system Final Products of Cellular Respiration (Aerobic) • Through Aerobic Respiration a yield of 36 ATP can be produced from 1 glucose. – 2 – Glycolysis – 2 - Krebs cycle – 32 - Electron Transport Chain • Quick energy – lactic acid fermentation – anaerobic • Long lasting energy – aerobic cellular respiration 3 steps. • When beginning a race, our bodies will use all 3 sources of ATP; ATP already in the muscles, new ATP made by lactic acid fermentation, and ATP made in Cellular Respiration. 35-39% efficient. The rest is lost as heat. • Plants need to make ATP as well!! • Other compounds come from the Krebs Cycle. Example: amino acids, proteins, ions. • • • • • • • Plants Use Oxygen Too You know that plants give off oxygen. But, there is a problem with knowing that fact. Sometimes knowledge of one thing can interfere with knowing something else. That's what happens in this case. People who know that plants give off oxygen often assume that plants must not also take it in. But this assumption is wrong. All living things--plants included-- take in oxygen from the air. Plant cells have special structures called chloroplasts--named for the chlorophyll they contain. Plants use chlorophyll to capture energy from the sun, then they use that energy to make food in a process called photosynthesis. The food is made by combining small molecules of water with small molecules of carbon dioxide to make larger molecules of starch and sugar. (Oxygen is released as a byproduct of photosynthesis.) The starch and sugar are stored by the plant then used by us when we eat plants. But feeding us is not why a plant goes to all the trouble of making starch and sugar. Plants use the food they make to fuel their own growth and activities. And that's where oxygen comes in again. To "burn" fuel requires oxygen. Animals breathe in oxygen and use it to extract energy from food. This process of using oxygen to release energy from food is called respiration. Plants use oxygen in exactly the same way! But when you have lots of phytoplankton growing in water that's too warm to hold much oxygen, there is little o no oxygen for fish. Algae Bloom.