“Let’s Take a Breather”. Cellular Respiration “Let’s Take a Breather”.

Cellular Respiration C6H12O6 + 6O2 -----> 6CO2 + 6H20 + energy (heat and ATP) Energy Capacity to move or change matter Forms of energy are important to life include Chemical, radiant (heat & light), mechanical, and electrical

Energy can be transformed from one form to another Chemical energy is the energy contained in the chemical bonds of molecules Radiant energy travels in waves and is sometimes called electromagnetic energy. An example is visible light

Visible Spectrum of White Light

Other wavelengths

Photosynthesis converts light energy to chemical energy Energy that is stored is called potential energy

Adenosine triphosphate (ATP) Energy carrying molecule used by cells to fuel their cellular processes ATP is composed of an adenine base, ribose sugar, & 3 phosphate (PO4) groups The PO4 bonds are high-energy bonds that require energy to be made & release energy when broken

ATP is made & used continuously by cells Every minute all of an organism's ATP is recycled Phosphorylation refers to the chemical reactions that make ATP by adding Pi to ADP

Cellular Respiration Overview: C6H12O6 + 6O2 -----> 6CO2 + 6H20 + energy (heat and ATP) Controlled release of energy from organic molecules (most often glucose) Glucose is oxidized (loses e-) & oxygen is reduced (gains e-) The carbon atoms of glucose (C6H12O6) are released as CO2

Generates ATP (adenosine triphosphate) The energy in one glucose molecule may be used to produce 36 ATP Involves a series of 3 reactions --- Glycolysis, Kreb's Cycle, & Electron Transport Chain

Glycolysis: Occurs in the cytoplasm Summary of the steps of Glycolysis: a. 2 ATP added to glucose (6C) to energize it. b. Although glycolysis makes 4 ATP, the net ATP production by this step is 2 ATP (because 2 ATP were used to start glycolysis). The 2 net ATP are available for cell use.

c. If oxygen is available to the cell, the pyruvate will move into the mitochondria & aerobic respiration will begin. Net Yield from Glycolysis 4 NADH2 2 CO2 4 ATP ( 2 used to start reaction)

d. If no oxygen is available to the cell (anaerobic), the pyruvate will be fermented by addition of 2 H from the NADH (to alcohol + CO2 in yeast or lactic acid in muscle cells). This changes NADH back to NAD+ so it is available for step c above. This keeps glycolysis going!

Types of Fermentation: A. Alcoholic Fermentation—Alcohol (Wine, Beer) B. Lactic Acid Ferm.

Aerobic Respiration: Occurs in the mitochondria Includes the Krebs Cycle & the Electron Transport Chain (ETC) CO2 and NADH are also produced

Kreb's Cycle: Named for biochemist Hans Krebs Metabolic pathway that indirectly requires O2 Kreb's Cycle is also known as the Citric acid Cycle Requires 2 cycles to metabolize glucose CO2 is a waste product that diffuses out of cells

Kreb Cycle Produces: 6 NADH2 2 FADH2 4 CO2 2 ATP

Net Yield from Kreb's Cycle (2 turns) 6 NADH2 2 FADH2 4 CO2 2 ATP

Electron Transport Chain: Found in the inner mitochondrial membrane Contains 4 protein-based complexes that work in sequence moving H+ from the matrix across the inner membrane (proton pumps) Energized e- & H+ from the 10 NADH2 and 2 FADH2 (produced during glycolysis & Krebs cycle) are transferred to O2 to produce H2O (redox reaction) O2  +  4e-  +  4H+  2H2O

Electron Transport At the end of the electron transport chain, the electrons combine with H+ ions and oxygen to form water.

Energy Yield from Aerobic Respiration Glycolysis Kreb's Cycle Total 4 NADH2 6 NADH2 10 NADH2 x 3 = 30 ATP 0 FADH2 2 FADH2 2 FADH2 x 2 = 4 ATP 2 ATP 2 ATP 4 ATP Total: 38 ATP

Most cells produce 36- 38 molecules of ATP per glucose (66% efficient) Actual number of ATP's produced by aerobic respiration varies among cells