Cell Respiration and Fermentation

Cell Respiration Cell Respiration is the process of breaking down organic compounds (glucose) to produce ATP Requires the use of mitochondria Both autotrophs and heterotrophs use cell respiration Cell respiration is divided into 2 stages: Glycolysis Aerobic Respiration

Circle of Life Cell Respiration mirrors photosynthesis: Light + 6H2O + 6CO2  C6H12O6 + 6O2 Cell Respiration: C6H12O6 + 6O2  6H2O + 6CO2 + ATP

Cell Respiration Cell Respiration is divided into 2 stages: 1st Step: Glycolysis 2nd Step: Aerobic Respiration

1st Step: Glycolysis Glycolysis occurs in the cytoplasm where glucose is broken down. 2 pyruvic acid molecules & net of 2 ATP molecules are formed Pyruvic acid must be broken down further through the process of aerobic respiration or anaerobic respiration (depending on the availability of O2)

2nd Step: Aerobic Respiration Pathway Aerobic Respiration takes place in the mitochondria in all eukaryotes only if oxygen is present in the cell. There are 2 steps to Aerobic Respiration: Krebs Cycle Electron Transport Chain (ETC)

Krebs Cycle: 1st Part of Aerobic Respiration The Krebs cycle takes place in the mitochondrial matrix Breaks down Pyruvic acid from glycolysis to produce CO2 and net 2 ATP Produces NADH and FADH2 molecules (energy molecules) to power the Electron Transport Chain (ETC)

ETC: 2nd Part of Aerobic Respiration The Electron transport chain (ETC) takes place on the inner membrane of the mitochondria. Electrons from NADH and FADH2 are passed molecule-to-molecule in the ETC allowing for ATP Synthase to produce ATP End Products for ETC are H2O and 34 ATP molecules

Fermentation Pathway Anaerobic Respiration is also known as Fermentation Fermentation is an additional biochemical pathway if oxygen is not present in the cell Anaerobic Respiration occurs only in the cytoplasm There are 2 steps to fermentation: Glycolysis – breaking down glucose into pyruvic acid Anaerobic Respiration (Fermentation) – breaking down pyruvic acid in one of the 2 pathways: alcoholic fermentation or lactic acid fermentation

Lactic Acid Fermentation Lactic acid fermentation is the biochemical pathway converting pyruvic acid into lactic acid without producing additional ATP Lactic acid fermentation occurs with muscle fatigue Can be used to make dairy products

Alcoholic Fermentation Alcoholic fermentation is the biochemical pathway converting pyruvic acid into ethyl alcohol and CO2 producing no additional ATP Can be used to make alcohol such as beer, wine, and bread.

Energy Produced by Cellular Respiration Cell Respiration can produce up to 38 ATP molecules from a single molecule of glucose Glycolysis produced 2 ATP molecules Aerobic respiration produced 36 ATP molecules Anaerobic Respiration produced – ATP Thus, cell respiration produced is nearly 20 times more efficient than glycolysis alone.