Cellular Respiration ( Aerobic/Anaerobic)

Background So far we have seen that energy enters a food chain through producers – Photosynthesis At the end of photosynthesis, the energy from the sun is now found in the bonds of glucose 6H 2 O + 6CO 2 + Light Energy  C 6 H 12 O 6 + 6O 2 (photosynthesis)

What is Cellular Respiration? Transformation of chemical energy in food into chemical energy cells can use: ATP These reactions proceed the same way in plants and animals. Process is called cellular respiration Overall Reaction: – C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + ATP

What are the Stages of Cellular Respiration? Glycolysis Glycolysis – Bacteria and yeast stop here The Krebs Cycle The Krebs Cycle The Electron Transport Chain The Electron Transport Chain

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

Glycolysis Occurs in the cytoplasm (gel bathing the interior of a cell). Glucose is split into two pyruvate (pyruvic acid) molecules.

All organisms go through glycolysis After glycolysis an organism will continue with aerobic cellular respiration if – The organism has a mitochondria and oxygen is present. If the organism does not have a mitochondria or oxygen is not present it will go through fermentation.

Fermentation Occurs when O 2 NOT present (anaerobic process)  Occurs when O 2 NOT present (anaerobic process)  Called Lactic Acid fermentation in muscle cells (makes muscles tired)  Called Alcoholic fermentation in yeast (produces ethanol, makes breads and alcoholic beverages)  Nets only 2 ATP

Kreb’s Cycle Completes the breakdown of glucose – Takes the pyruvate (3-carbons) and breaks it down, the carbon and oxygen atoms end up in CO 2 and H 2 O – Hydrogens and electrons are stripped and loaded onto NAD + and FAD to produce NADH and FADH2 Production of only 2 more ATP but loads up the coenzymes with H + and electrons which move to the 3 rd stage

Electron Transport Chain Electron carriers loaded with electrons and protons (H+) from the Kreb’s cycle move to this chain-like a series of steps (staircase). As electrons drop down stairs, energy is released to form a total of 32 ATP Oxygen waits at bottom of staircase, picks up electrons and protons and in doing so becomes water

Energy Tally 36 ATP for aerobic vs. 2 ATP for anaerobic – Glycolysis 2 ATP – Kreb’s 2 ATP – Electron Transport32 ATP 36 ATP Anaerobic organisms can’t be too energetic but are important for global recycling of carbon