Transcript Slide 1
Cellular Respiration Overview 1. Process by which cells break down foods such as glucose, fats, proteins to release their stored E 2. Two types: 1. Anaerobic – NO O2 needed 2. Aerobic – O2 needed 3. Both produce E-storage molecules: ATP or Adenosine Triphosphate http://www.chemistry.wustl.edu/~courses/genchem/ LabTutorials/Cytochromes/images/flowchart1.jpg Anaerobic Respiration • 1. No O2 required to drive this • 2. Includes: – a) Glycolysis – breakdown of glucose – b) Fermentation • Examples of anaerobes: yeast (fungus), some bacteria (Clostridrium, Bacillus) Glycolysis 1. Occurs in cytoplasm 2. Breaks 1 glucose into 2 pyruvic acids (3-C structures) 3. 2 ATPs formed 4. 2 NADH E-shuttle molecules formed 5. Pyruvic acid metabolized during fermentation http://www.emc.maricopa.edu/fac ulty/farabee/BIOBK/enyld1.gif Fermentation • Pyruvic acid metabolized by either: – Lactic Acid pathway – Alcoholic Fermentation pathway • Lactic acid pathway metabolizes pyruvic acid into lactic acid & NAD+ – NAD+ recycled back into glycolysis – Lactic acid build-up: • Useful: cheese making industry • Not beneficial: build up of lactic acid in exercising muscles causing pain, fatigue • Alcoholic fermentation pathway metabolizes pyruvic acid into ethyl alcholo & NAD+ – NAD+ recycled back into glycolysis – Ethyl alcohol build-up: • Useful: beverage & baking industries Efficiency of Glycolysis • Efficiency = E needed to make ATP x 100 E released by oxid. of glucose • Eff = (2) (12kCal) x 100 = 3.5% • 686 kCal • Is glycolysis very efficient in making ATP? Aerobic Respiration • Requires O2 ; occurs in mitochondria • Aerobic respiration the Kreb’s cycle & electron transport chain • Most organisms are aerobic • Equation: – 6C6H12O6 + 6O2 6CO2 + 6H2O + ATP • Why do humans and most other organisms breathe? • Mitochondria If O2 present following glyolysis, pyruvic acid modified & enters mitochondria of eukaryotes (or cytosol of prokaryotes) • In eukaryotes: pyruvic acid diffuses into mitochrondria matrix; it reacts forming acetyl CoA + NADH+ – Kreb’s cycle begins: acetyl CoAs break down into CO2 + H+ + ATP (takes ~5 steps) • Ultimately making glucose which further breaks down into 6NADH + 2 FADH2 + 2ATP + 4 CO2 – Electron Transport Chain finishes: (lines inner mitochondira membrane) chemiosynthesis occurs making up to 34 ATPs! Efficiency of Aerobic Respiration • Efficiency = E needed to make ATP x 100 E released by oxid. of glucose • Eff = (38) (12kCal) x 100 = 66% • 686 kCal • Are the Kreb’s cycle & ETC very efficient in making ATP? Role of O2 in Respiration • Energy carrier, NADH, drops off e- that enter the ETC, as e- move down chain toward O2, ATPs formed (our E payload molecules!) • At the end of the ETC, O2 picks up those fallen e- & H+ making water (H2O); which is a by product of respiration along with CO2 Adenosine Triphosphate 1. Energy molecule of cell 2. All cell activities powered by ATP 3. Structure: 1. 3 phosphates 2. Ribose sugar 3. N-base (adenine) ATP/ADP Cycle in Cell 1. ATP is constantly used and remade within cells to power the cell’s activities 2. E is released by breaking or stored by making phosphate bonds Respiration Overview Process Where it occurs Anaerobic: Cytoplasm Glycolysis & fermentation (LAF & AF) Aerobic: Kreb’s Mitochondria cycle & ETC Net gain of ATP/ glucose 2 ATPs 36 ATPs