Cellular Respiration

CELLULAR RESPIRATION C6H12O6 + 6O2  6CO2 + 6H2O + energy Catabolic (breaking down molecules), Exergonic (energy producing), oxygen (O2) requiring process that uses energy extracted from macromolecules (glucose) to produce energy (ATP) and water (H2O). In other words, cells transfer energy from food molecules to STP, the byproduct is water and carbon dioxide C6H12O6 + 6O2  6CO2 + 6H2O + energy glucose ATP

In what kinds organisms does cellular respiration take place? Question: In what kinds organisms does cellular respiration take place?

Plants and Animals Plants - Autotrophs: self-producers. Animals - Heterotrophs: consumers.

Mitochondria Organelle where cellular respiration takes place. Inner membrane space Matrix Cristae Outer membrane Inner membrane

THE BIG PICTURE The Big Picture

BREAKDOWN OF CELLULAR RESPIRATION Four main parts (reactions). 1. Glycolysis (splitting of sugar) a. Cytosol (cytoplasm), just outside of mitochondria. 2. Grooming Phase a. migration from cytosol to matrix.

BREAKDOWN OF CELLULAR RESPIRATION 3. Krebs Cycle (Citric Acid Cycle) a. mitochondrial matrix 4. Electron Transport Chain (ETC) and Oxidative Phosphorylation a. Also called Chemiosmosis b. inner mitochondrial membrane.

1. GLYCOLYSIS Means “splitting glucose”. Glucose is broken down into 2 pyruvate molecules. Occurs in the cytoplasm (cytosol) just outside of mitochondria. It is anaerobic which means it does NOT require oxygen. YEILDS: 2 ATP, 2 NADPH, 2 pyruvate

1. GLYCOLYSIS TAKE NOTE: In all cells, all of the main energy releasing pathways start with the same reactions in the cytoplasm/cytosol.

1. GLYCOLYSIS Two phases (10 steps): A. Energy investment phase a. Preparatory phase (first 5 steps). B. Energy yielding phase a. Energy payoff phase (second 5 steps).

1. GLYCOLYSIS A. Energy Investment Phase: C-C-C-C-C-C C-C-C Glucose (6C) Glyceraldehyde phosphate (2 - 3C) (G3P or GAP) 2 ATP - used 0 ATP - produced 0 NADH - produced 2ATP 2ADP + P

1. GLYCOLYSIS B. Energy Yielding Phase Glyceraldehyde phosphate (2 - 3C) (G3P or GAP) Pyruvate (2 - 3C) (PYR) 0 ATP - used 4 ATP - produced 2 NADH - produced 4ATP 4ADP + P C-C-C C-C-C GAP (PYR)

1. GLYCOLYSIS Total Net Yield 2 - 3C-Pyruvate (PYR) 2 - ATP (Substrate-level Phosphorylation) 2 – NADH (4 ATP are made, but two are used to get the process started so the net ATP is 2.)

SUBSTRATE-LEVEL PHOSPHORYLATION ATP is formed when an enzyme transfers a phosphate group from a substrate to ADP. Enzyme Substrate O- C=O C-O- CH2 P Adenosine ADP (PEP) Example: PEP to PYR P ATP O- C=O CH2 Product (Pyruvate) Adenosine

1. GLYCOLYSIS Glycolysis

FERMENTATION Called anaerobic. Occurs in cytoplasm when cells are deprived of oxygen. Lactic acid forms during increased muscle activity. Cramps result from increased acidity level. Alcohol fermentation occurs in fungi such as yeast and some bacteria produce ethanol and CO2.

FERMENTATION Remember: glycolysis is part of fermentation. Two Types: 1. Alcohol Fermentation 2. Lactic Acid Fermentation

ALCOHOL FERMENTATION Plants and Fungi  beer and wine 2ATP C P 2NADH C glucose Glycolysis C C C 2 Pyruvic acid 2ATP 2ADP + 2 2NADH P 2 NAD+ C 2 Ethanol 2CO2 released 2NADH 2 NAD+

ALCOHOL FERMENTATION End Products: Alcohol fermentation 2 - ATP (substrate-level phosphorylation) 2 - CO2 2 - Ethanols

LACTIC ACID FERMENTATION Animals (pain in muscle after a workout). Glucose Glycolysis C 2 Pyruvic acid 2ATP 2ADP + 2 2NADH P 2 NAD+ C C 2 Lactic acid 2NADH 2 NAD+ C

LACTIC ACID FERMENTATION End Products: Lactic acid fermentation 2 - ATP (substrate-level phosphorylation) 2 - Lactic Acids

2. GROOMING PHASE Occurs when Oxygen is present (aerobic). 2 Pyruvate (3C) molecules are transported through the mitochondria membrane to the matrix and is converted to 2 Acetyl CoA (2C) molecules. Cytosol C 2 Pyruvate 2 CO2 2 Acetyl CoA C-C 2NADH 2 NAD+ Matrix

2. GROOMING PHASE End Products: grooming phase 2 - NADH 2 - CO2 2- Acetyl CoA (2C)

3. KREBS CYCLE (CITRIC ACID CYCLE) Aerobic which means it requires O2. Each Acetyl-CoA enters the Krebs Cycle resulting in two complete cycles to get yield.

3. KREBS CYCLE (CITRIC ACID CYCLE) Location: mitochondrial matrix. Acetyl CoA (2C) bonds to Oxalacetic acid (4C - OAA) to make Citrate (6C). It takes 2 turns of the krebs cycle to oxidize 1 glucose molecule. Mitochondrial Matrix

3. KREBS CYCLE (CITRIC ACID CYCLE) 1 Acetyl CoA (2C) 3 NAD+ 3 NADH FAD FADH2 ATP ADP + P (one turn) OAA (4C) Citrate (6C) 2 CO2

3. KREBS CYCLE (CITRIC ACID CYCLE) 2 Acetyl CoA (2C) 6 NAD+ 6 NADH 2 FAD 2 FADH2 2 ATP 2 ADP + P (second turn) OAA (4C) Citrate (6C) 4 CO2

3. KREBS CYCLE (CITRIC ACID CYCLE) Total net yield (2 turns of krebs cycle) 1. 2 - ATP (substrate-level phosphorylation) 2. 6 – NADH  3. 2 - FADH2 4. 4 - CO2 **Your notes say 8 because they are counting the two from the Grooming phase.

3. KREBS CYCLE Krebs Cycle

4. Electron Transport Chain (ETC) and Oxidative Phosphorylation (Chemiosmosis) Aerobic Occurs in the cristae of the mitochondria. Electron acceptors in the chain accept NADH/FADH2 electrons. As electrons pass down a series of molecules to O2 – the O2 combines with H atoms to form H2O and ATP.

4. Electron Transport Chain (ETC) and Oxidative Phosphorylation (Chemiosmosis) Location: inner mitochondrial membrane. Uses ETC (cytochrome proteins) and ATP Synthase (enzyme) to make ATP. ETC pumps H+ (protons) across inner membrane (lowers pH in inner membrane space). Inner Mitochondrial Membrane

4. Electron Transport Chain (ETC) and Oxidative Phosphorylation (Chemiosmosis) The H+ then move via diffusion (Proton Motive Force) through ATP Synthase to make ATP. All NADH and FADH2 converted to ATP during this stage of cellular respiration. Each NADH converts to 3 ATP. Each FADH2 converts to 2 ATP (enters the ETC at a lower level than NADH).

4. Electron Transport Chain (ETC) and Oxidative Phosphorylation (Chemiosmosis) Inner membrane space Matrix Cristae Outer membrane Inner membrane

4. ETC and Oxidative Phosphorylation (Chemiosmosis for NADH) ATP Synthase 1H+ 2H+ 3H+ higher H+ concentration H+ ADP + lower H+ (Proton Pumping) P E T C NAD+ 2H+ + 1/2O2 H2O Intermembrane Space Matrix Inner Mitochondrial Membrane

4. ETC and Oxidative Phosphorylation (Chemiosmosis for FADH2) ATP Synthase 1H+ 2H+ higher H+ concentration H+ ADP + lower H+ (Proton Pumping) P E T C FAD+ 2H+ + 1/2O2 H2O Intermembrane Space Matrix Inner Mitochondrial Membrane

Electron Transport Chain 4. Electron Transport Chain (ETC) and Oxidative Phosphorylation (Chemiosmosis) YEILD: 10 NADH converts to 30 ATP 2 FADH2 converts to 4 ATP Remember FADH produces 2 ATP and NADH produces 3 ATP. Electron Transport Chain

ATP NET ATP YIELD 04 ATP - substrate-level phosphorylation 02 ATP – Krebs Cycle 32 ATP - ETC & oxidative phosphorylation 38 ATP – TOTAL -02 ATP used in glycolysis 36 ATP – NET TOTAL YIELD ATP

EUKARYOTES Total ATP Yield 02 ATP - glycolysis (substrate-level phosphorylation) 04 ATP - converted from 2 NADH - glycolysis 06 ATP - converted from 2 NADH - grooming phase 02 ATP - Krebs cycle (substrate-level phosphorylation) 18 ATP - converted from 6 NADH - Krebs cycle 04 ATP - converted from 2 FADH2 - Krebs cycle 36 ATP - TOTAL All from one glucose molecule!

MAX ATP YIELD FOR CELLULAR RESPIRATION (EUKARYOTES) Glucose Glycolysis 2ATP 4ATP 6ATP 18ATP 4ATP 2ATP 2 ATP (substrate-level phosphorylation) 2NADH 6NADH Krebs Cycle 2FADH2 2 Pyruvate 2 Acetyl CoA ETC and Oxidative Phosphorylation Cytosol Mitochondria 36 ATP (maximum per glucose)

PROKARYOTES Total ATP Yield 02 ATP - glycolysis (substrate-level phosphorylation) 06 ATP - converted from 2 NADH - glycolysis 06 ATP - converted from 2 NADH - grooming phase 02 ATP - Krebs cycle (substrate-level phosphorylation) 18 ATP - converted from 6 NADH - Krebs cycle 04 ATP - converted from 2 FADH2 - Krebs cycle 38 ATP - TOTAL

QUESTION: In addition to glucose, what other various food molecules are use in Cellular Respiration?

CATABOLISM OF VARIOUS FOOD MOLECULES Other organic molecules used for fuel. Carbohydrates: polysaccharides Fats: glycerol’s and fatty acids (during starvation, fasting, untreated diabetes) Proteins: amino acids (if there are excess proteins or not fats or sugars.)