Cellular Respiration. How Cells Harvest Chemical Energy – Cellular Respiration. Cellular Respiration. C 6 H 12 O 6 + 60 2 6CO 2 + 6H 2 0 A catabolic pathway Oxygen is consumed as a reactant along with organic compounds. Involves three stages: Glycolysis Krebs Cycle
Cellular Respiration How Cells Harvest Chemical Energy – Cellular Respiration
Cellular Respiration • C6H12O6 + 602 6CO2 + 6H20 • A catabolic pathway • Oxygen is consumed as a reactant along with organic compounds. • Involves three stages: • Glycolysis • Krebs Cycle • Electron Transport Chain
What Is ATP? • Adenosine Triphosphate • Energy used by all Cells • Organic molecule containing high-energy Phosphate bonds
What Does ATP Do for You? • It supplies YOU withENERGY!
By breaking the high- energy bonds between the last two phosphates in ATP How Do We Get Energy From ATP?
NAD+ traps electrons from glucose to make NADH (energy stored) Similarly, FAD+ stores energy as FADH2 NADH and FADH2
Where Does Cellular Respiration Take Place? • It actually takes place in two parts of the cell: • Glycolysis occurs in the Cytoplasm • Krebs Cycle & ETC Takeplace in the Mitochondria
Smooth outer Membrane Folded inner membrane Folds called Cristae Space inside cristae called the Matrix Review of Mitochondria Structure
Diagram of the Process Occurs in Matrix Occurs across Cristae Occurs in Cytoplasm
Glycolysis 1. Means “splitting of sugar” 2. Occurs in the cytosol of the cell 3. Partially oxidizes glucose (6C) into two pyruvate (3C) molecules. 4. Occurs whether or not oxygen is present.
5. An exergonic process, (meaning energy is released) most of the energy harnessed is conserved in the high-energy electrons of NADH and in the phosphate bonds of ATP
Glycolysis Summary • Takes place in the Cytoplasm • Anaerobic (Doesn’t Use Oxygen) • Requires input of 2 ATP • Glucose split into two molecules of Pyruvate • Also produces 2 NADH and 4 ATP
Formation of Acetyl CoA 1. Junction between glycolysis and Krebs cycle 2. Oxidation of pyruvate to acetyl CoA 3. Pyruvate molecules are translocated from the cytosol into the mitochondrion by a carrier protein in the mitochondrial membrane. 4. A CO2is removed from pyruvate – making a 2C compound. 5. Coenzyme A is attached to the acetyl group.
Krebs Cycle • Requires Oxygen (Aerobic) • Cyclical series of oxidation reactions that give off CO2 and produce one ATP per cycle • Turns twice per glucose molecule • Produces two ATP • Takes place in matrix of mitochondria
Krebs Cycle Summary • Each turn of the Krebs Cycle also produces 3NADH, 1FADH2, and 2CO2 • Therefore, For each Glucose molecule, the Krebs Cycle produces 6NADH, 2FADH2, 4CO2, and 2ATP
Electron Transport Chain 1. Located in the inner membrane of the mitochondria. 2. Oxygen pulls the electrons from NADH and FADH2 down the electron transport chain to a lower energy state . 3. Process produces 34 ATP or 90% of the ATP in the body.
Electron Transport Chain 4. Requires oxygen, the final electron acceptor. 5. For every FADH2 molecule – 2 ATP’s are produced. 6. For every NADH molecule – 3 ATP’s are produced. 7. Chemiosmosis – the production of ATP using the energy of H+ gradients across membranes to phosphorylate ADP.
ATP Synthase • A protein in the inner membrane in the mitochondria. • Uses energy of the ion gradient to power ATP synthesis. • For every H+ ion that flows through ATP synthase, one ATP can be formed from ADP
Cellular Respiration in Summary Glycolysis • 2 ATP • 2 NADH 4-6 ATP (Depends on how this NADH molecule gets to the ETC. To make things simple we will say that these two NADH’s make 4 ATP ) Formation of Acetyl CoA • 2 NADH 6 ATP
Cellular Respiration in Summary Krebs Cycle • 2 ATP • 6 NADH 18 ATP • 2 FADH2 4 ATP Grand Total = 36 ATP
Fermentation • Occurs when O2 NOT present (anaerobic) • Called Lactic Acid fermentation in muscle cells (makes muscles tired) • Called Alcoholic fermentation in yeast (produces ethanol) • Nets only 2 ATP