Aerobic Respiration Chapter 9-2

Cellular Respiration Aerobic  requires oxygen –It’s the final step 90% of the energy from the original glucose is still present in the 2 pyruvic acids 3 steps: Glycolysis, Krebs cycle, ETC Takes place in the mitochondria

MITOCHONDRION –Highly folded inner membrane = cristae –Liquid space inside = matrix -Krebs cycle occurs in the matrix -ETC proteins are in inner membrane. -H+ ions are pumped out of the matrix into inner membrane space -H+ ions then diffuse back into matrix through ATPsynthase

Pyruvic acid is broken down into CO 2 in a series of energy-extracting reactions. The Krebs Cycle

Steps of the Krebs Cycle A 1. Pyruvic acid (3C from glycolysis) enters mitochondrion – across 2 membranes 2. 3C (pyruvic acid) splits: 1 C becomes CO 2 and is released. The remaining 2C combine with coenzyme A  now called acetyl CoA 3. acetyl group (2C) combines with 4C molecule (already in mitochondrion) to form citric acid (6C)

Pyruvic acid + Coenzyme A  CO 2 + acetyl CoA First step after glycolysis Link between glycolysis and the cycle part

Krebs Cycle cont. B 1. Citric acid (6C) loses 1carbon as CO 2 and makes a 5-C molecule and NADH 2. The 5-C loses another carbon as CO 2 and makes a 4-C molecule, NADH and ATP* 3. This 4-C molecule rearranges again & again, giving off Hydrogens as FADH 2 and NADH

Krebs Cycle Cycle continues : this 4C molecule combines with acetyl CoA to start cycle again. Cycle goes around once per molecule of pyruvic acid Therefore, it goes around twice per molecule of glucose

Krebs Cycle Outcome PER GLUCOSE: (2 turns of cycle) 6 CO 2 2 ATP electron8 NADH carriers to2 FADH 2 ETC  10 pair of e-

Video 3 Click the image to play the video segment. Video 3 Krebs Cycle, Part 1

Video 4 Click the image to play the video segment. Video 4 Krebs Cycle, Part 2

Electron Transport Chain Section 9-2 Electron Transport Hydrogen Ion Movement ATP Production ATP synthase Channel Inner Membrane Matrix Intermembrane Space Mitochondrion

Electron Transport Chain High-energy electrons from the Krebs cycle (carried by NADH and FADH2) are used to convert ADP to ATP The high-energy electrons are passed along a series of proteins embedded in the inner membrane of the mitochondria –This is in eukaryotes –Prokaryotes don’t have organelles, so this process occurs directly in the cell membrane

Electron Transport Chain 1. NADH and FADH2 from Krebs cycle (in matrix) transfer high energy e- to proteins of membrane. 2. e- are passed from one protein to the next in the chain. For each pair of e-, H+ ions are pumped out of matrix, across membrane, into intermembrane space. 3. When e- get to the end, an enzyme joins them with H+ ions and O 2 to form water

This is why it’s aerobic! In order for the chain to work, there must be a molecule at the end to accept the electrons. Oxygen is this final electron acceptor. The electrons combine with free hydrogens to form water

Electron Transport Chain 5. The H+ that were pumped into intermembrane space begin building up, creating a positive charge -- (likewise, the matrix is negative now) 6. This high concentration of positive charge wants to even out. The H+ ions will diffuse back across the inner membrane, through ATP synthetase. 7. As H+ move through the ATP synthetase protein, it spins, combining ADP and P to form ATP

Video 5 Click the image to play the video segment. Video 5 Electron Transport Chain, Part 1

Video 6 Click the image to play the video segment. Video 6 Electron Transport Chain, Part 2

TOTALS On Average: each pair of e- along the ETC provides enough energy to convert 3 ADP to 3 ATP 1 NADH  3 ATP 1 FADH2  2 ATP Totals will depend on whether you’re talking about 1 turn of the Krebs cycle or 2 turns: 1 pyruvic acid or 2 pyruvic acid (1 glucose)

TOTAL ATP Remember: Cellular respiration includes 3 steps: glycolysis, Krebs, ETC Per Glucose molecule: 2 ATP from glycolysis 34 ATP from Krebs/ETC= 18X more! ATP total = 38% of total original energy in a glucose molecule. 62% is lost as heat  why you get warmer exercising

Exercising Stores 1 st  stores of ATP already in cell - enough for a few seconds 2 nd  lactic acid fermentation - enough for ~90seconds - builds up lactic acid & oxygen debt 3 rd  cellular respiration (Krebs & ETC) - long-term energy - slow release as glycogen stores are broken down (15-20 min) - after 20 min, body starts breaking down other stores (like fat)

Which forms use aerobic? anaerobic? Weight-lifting Marathon running 50 meter dash Playing soccer Playing basketball AEROBIC Long-term, slow release Cellular respiration –Marathon –Soccer (80%) –Basketball (80%) ANAEROBIC Quick stores, used up Lactic acid fermentation –Weight-lifting –50 meter dash

Tricky part… 6CO 2 + 6H light  C 6 H 12 O 6 + 6O 2 C 6 H 12 O 6 + 6O 2  6CO 2 + 6H energy Plants do both processes! Plants have chloroplasts & mitochondria

Energy In vs. Energy Out PhotosynthesisRespiration FunctionEnergy StorageEnergy Release LocationChloroplastsMitochondria Reactant s Carbon dioxide & waterSugar & oxygen ProductsSugar & oxygenCarbon dioxide & water Equation6CO 2 + 6H λ  C 6 H 12 O 6 + 6O 2 C 6 H 12 O 6 + 6O 2  6CO 2 + 6H energy

GlycolysisKrebs CycleETCFermentation Lactic acid fermentation Alcoholic fermentation If Oxygen If no Oxygen

ProcessATPmadeNADHmadeFADHmadeCO2madeO2usedNADHusedFADHused Glycolysis Kreb’s cycle ETC

ProcessATPmadeNADHmade FADH 2 made CO 2 made O 2 usedNADHused FADH 2 used Glycolysis2 (4)2 Kreb’s cycle 2826 ETC Net number (Gross number)

Extra slides Pyruvate (C 3 H 4 O 3 ) Lactic Acid (C 3 H 6 O 3 )C H O

Mighty-Tighty Mitochondria 1. Obtain two sheets of paper and a metric ruler. What is the surface area of the paper? 2.Roll one sheet of paper into a tube lengthwise. What is the surface area of the rolled paper? 3.Fold the second sheet of paper into a fan. Then, roll the first sheet of paper around the folded paper so it is inside the rolled paper. What has happened to the surface area of the inside of the rolled paper? 4.What would be the value of increasing the surface area of the membrane inside a mitochondrion