2 Nutrients + oxygen water+ ATP+ CO2 Cellular respiration – process in which mitochondria break down food molecules to produce ATP in plants & animals; occurs in the presence of oxygenNutrients + oxygen water+ ATP+ CO2The equation for cellular respiration is:6O2 + C6H12O6 → 6CO2 + 6H2O + Energyoxygen + glucose → carbon dioxide + water + energyProcess changes organic chemical energy (glucose) into inorganic chemical energy ATP
3 Overview of Cellular Respiration 3 Stages:Glycolysis – anaerobic process; does not require oxygen - cytoplasmCitric Acid (Krebs) Cycle – aerobic; does require oxygen – mitochondriaElectron Transport Chain – aerobic; does require oxygen - mitochondria
4 GlycolysisGlycolysis – breaks down glucose into two molecules of pyruvic acid (colorless acid)This reaction uses enzymes and takes place in the cytoplasm of the cell (anaerobic reaction)Produces:2 Pyruvic acid molecules (used in Step 2 of cellular respiration)2 ATP molecules (energy cell can use)2 NADH molecules (electron carrier)
5 At the beginning of glycolysis, the cell uses up 2 molecules of ATP to start the reaction. 4 ADP2 ATP4 ATP2 ADP2 ATP2NAD+2 Pyruvicacid2To the electron transport chain
6 FermentationFermentation releases energy from food molecules by producing ATP in the absence of oxygen; anaerobic processDuring fermentation, cells convert NADH to NAD+ by passing high- energy electrons back to pyruvic acid.This action converts NADH back into NAD+, and allows glycolysis to continue producing a steady supply of ATP.
7 2 Types of Fermentation1. Lactic acid fermentation – process that supplies energy when O2 is scarceEx.) released during vigorous exercise; “feel the burn”2. Alcoholic fermentation – used to produce CO2 and ethyl alcoholEx.) Yeast Cells
8 The Krebs CycleNamed after Hans Krebs – British biochemist; won Nobel Prize in 1953 for discovery of this cycleAerobic processPyruvic acid produced from glycolysis along w/O2 start the 2nd stage of cellular respirationPyruvic acid is broken down into CO2 in a series of endergonic reactions
9 2 Parts of the Krebs Cycle Part A Step 1: Cycle begins when pyruvic acid enters the mitochondrion
10 The Krebs Cycle2. Carbon molecule is removed, forming CO2, & electrons are removed, changing NAD+ to NADH.3. Coenzyme A joins the 2-carbon molecule, forming acetyl-CoA.
11 The Krebs Cycle Citric acid 4. Acetyl-CoA then adds the 2-carbon acetyl group to a 4-carbon compound, forming citric acid.Citric acid
12 The Krebs CyclePart BStep 1: Citric acid is broken down into a 5-carbon compound, then into a 4-carbon compound.
13 The Krebs CycleStep 2: Two more molecules of CO2 are released and electrons join NAD+ and FAD, forming NADH and FADH2.
14 The Krebs CycleResult: 1 molecule of ATP is produced
15 Energy totals from 1 molecule of pyruvic acid is : 4 NADH1 FADH21 ATPElectron Transport Chain = 3rd step in cellular respiration, aerobic process, uses the high-energy electron carriers from the Krebs Cycle to convert ADP into ATP.Carrier molecules produced are used to generate ATP via the Electron Transport Chain
16 Electron Transport Chain High-energy electrons from NADH and FADH2 are passed along the electron transport chain from one carrier protein to the next.
17 The TotalsGlycolysis produces just 2 ATP molecules per molecule of glucose.The complete breakdown of glucose through cellular respiration, including glycolysis, results in the production of 36 molecules of ATP.
19 Comparing Photosynthesis and Cellular Respiration The energy flows in photosynthesis and cellular respiration take place in opposite directions.
20 On a global level, photosynthesis and cellular respiration are also opposites. Photosynthesis removes carbon dioxide from the atmosphere and cellular respiration puts it back.Photosynthesis releases oxygen into the atmosphere and cellular respiration uses that oxygen to release energy from food.