Cellular Respiration & Fermentation

Aerobic Cellular Respiration The process that involves oxygen and breaks down food molecules to release useable energy…. ATP !!! Cellular Respiration happens in 3 steps 1. Glycolysis 2. Krebs Cycle 3. Electron Transport Chain

Cellular Respiration Creates molecules of ATP

The Chemical Pathways Cellular Respiration Flow Glucose GlycolysisKrebs cycle Electron transport Fermentation (without oxygen) Alcohol or lactic acid O 2 Present No O 2 Present

What is Cellular Respiration? Respiration Equation C 6 H 12 O O 2 6CO 2 + 6H 2 0 ***NoTiCe: This is the reverse equation for photosynthesis MUST HAVE OXYGEN PRESENT!

Where does Cellular Respiration Happen? Glucose Glycolysis Cytoplasm Electrons carried in NADH Pyruvic acid Krebs Cycle Electrons carried in NADH and FADH 2 Mitochondria Electron Transport Chain

Photosynthesis and Cellular Respiration The products of one reaction are the reactants of the other reaction. Photosynthesis Cellular Respiration

Sunlight energy Ecosystem Photosynthesis (in chloroplasts) Cellular respiration (in mitochondria) Useable energy Heat energy

Krebs Cycle & Electron Transport Chain

Under Anaerobic Conditions Fermentation Fermentation occurs in cells where oxygen can be a toxic element or is not present. NO O 2 present! “No O – No go!” (into Krebs Cycle/ETC)

2 Types of Fermentation If there is no oxygen, the pyruvate formed during glycolysis will be broken down again to either lactic acid or ethanol

Lactic Acid Fermentation Lactic acid Fermentation – fermentation that produces lactic acid Pyruvic acid + NADH  lactic acid and NAD+ The NAD+ helps provide energy to keep glycolysis going. Occurs mostly in animals muscle cells & some bacteria Lactic acid burns! Muscles hurt!

Lactic Acid Fermentation IN: Pyruvic Acid NADH OUT: Lactic Acid NAD+

(a) Lactic acid fermentation 2 ADP+ 2 Glycolysis Glucose 2 Pyruvic acid 2 NAD  + 2 H  2 NAD  2 Lactic acid

Alcoholic Fermentation Alcoholic fermentation – fermentation that produces alcohol Pyruvic acid + NADH  alcohol + CO2 + NAD+ Occurs in yeast and a few other microorganisms

Alcoholic Fermentation IN Pyruvic acid NADH OUT Alcohol CO2 NAD+ What form does CO2 take? That’s right…gas! & when there is gas in liquids we see…. BUBBLES

(b) Alcoholic fermentation 2 ADP+ 2 2 ATP Glucose 2 NAD  Glycolysis 2 Pyruvic acid + 2 H  2 CO 2 released 2 NAD  2 Ethyl alcohol

Fermentation Process of energy production in the absence of oxygen Glycolysis and fermentation together only produces 2 ATP. This is not efficient!!

Why Fermentation? It does not produce usable energy…ATP so why bother? NADH is converted to NAD+ NAD+ is needed for glycolysis