Cellular Respiration How Cells Harvest Chemical Energy Cellular

Cellular Respiration How Cells Harvest Chemical Energy – Cellular Respiration

Cellular Respiration • C 6 H 12 O 6 + 602 6 CO 2 + 6 H 20 • 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

Chemical Structure of ATP

What Does ATP Do for You? l It supplies YOU with ENERGY!

How Do We Get Energy From ATP? l By breaking the high- energy bonds between the last two phosphates in ATP

NADH and FADH 2 l NAD+ traps electrons from glucose to make NADH (energy stored) l Similarly, FAD+ stores energy as FADH 2

Where Does Cellular Respiration Take Place? l It actually takes place in two parts of the cell: • Glycolysis occurs in the Cytoplasm • Krebs Cycle & ETC Take place in the Mitochondria

Review of Mitochondria Structure l l Smooth outer Membrane Folded inner membrane Folds called Cristae Space inside cristae called the Matrix

Diagram of the Process Occurs in Matrix Occurs in Cytoplasm Occurs across Cristae

Glycolysis 1. Means “splitting of sugar” 2. Occurs in the cytosol of the cell 3. Partially oxidizes glucose (6 C) into two pyruvate (3 C) 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 highenergy 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 Co. A 1. Junction between glycolysis and Krebs cycle 2. Oxidation of pyruvate to acetyl Co. A 3. Pyruvate molecules are translocated from the cytosol into the mitochondrion by a carrier protein in the mitochondrial membrane. 4. A CO 2 is removed from pyruvate – making a 2 C compound. 5. Coenzyme A is attached to the acetyl group.

Formation of Acetyl Co. A

Formation of Acetyl Co. A

Krebs Cycle l l l Requires Oxygen (Aerobic) Cyclical series of oxidation reactions that give off CO 2 and produce one ATP per cycle Turns twice per glucose molecule Produces two ATP Takes place in matrix of mitochondria

Krebs Cycle Summary l Each turn of the Krebs Cycle also produces 3 NADH, 1 FADH 2, and 2 CO 2 l Therefore, For each Glucose molecule, the Krebs Cycle produces 6 NADH, 2 FADH 2, 4 CO 2, and 2 ATP

Electron Transport Chain 1. Located in the inner membrane of the mitochondria. 2. Oxygen pulls the electrons from NADH and FADH 2 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 FADH 2 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 l A protein in the inner membrane in the mitochondria. l Uses energy of the ion gradient to power ATP synthesis. l 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 Co. A • 2 NADH 6 ATP

Cellular Respiration in Summary Krebs Cycle • 2 ATP • 6 NADH 18 ATP • 2 FADH 2 4 ATP Grand Total = 36 ATP

Fermentation l l Occurs when O 2 NOT present (anaerobic) Called Lactic Acid fermentation in muscle cells (makes muscles tired) Called Alcoholic fermentation in yeast (produces ethanol) Nets only 2 ATP