Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Cell Respiration How Cells Harvest Energy Copyright © McGraw-Hill Companies Permission required for reproduction or display

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Using Chemical Energy to Drive Metabolism Autotrophs (producers) - Convert light energy into chemical energy.  Plants, some bacteria Heterotrophs (consumers) - Live on food (glucose) autotrophs produce.  All cells do this  Digestion - Breaking down large molecules with enzymes.  Catabolism (breaking molecules) - Releasing energy from C-H.

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies ATP and High Energy Electrons (NAD+) Glucose cannot be used directly  It is too much energy (like a $36 bill)  ATP and NAD+ are the change Glucose is broken down in two main steps  1 st step is anaerobic (no oxygen needed) - Glycolysis - 2 ATP - Occurs in the cytoplasm (outside the mitochondria) Glucose  2 Pyruvate + 2 ATP + electrons

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Cell Respiration  2 nd step is aerobic (needs oxygen) - Krebs Cycle/Citric Acid Cycle (in the matrix of mitochondria)  2 ATP - Electron Transport Chain (ETC)  In the folded membranes of the mitochondria (cristae)  Up to 32 more ATP  Oxygen gas accepts the low energy electrons at the end of the ETC  H 2 O is produced C 6 H 12 O O 2  6 CO H energy

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Aerobic Respiration Overview Copyright © McGraw-Hill Companies Permission required for reproduction or display

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Electron Transport Chain & Chemiosmosis The high energy electrons harvested from glucose are used to pump H+ (protons) out of the matrix to the inter membrane space by the electron transport chain.  Return of protons onto the matrix generates ATP. (chemiosmosis)

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Using Chemical Energy to Drive Metabolism Aerobic Respiration - Oxygen gas accepts the hydrogen atom and water forms. Anaerobic Respiration - Occurs when an inorganic molecule other than oxygen accepts the hydrogen.  Fermentation - Occurs when an organic molecule accepts the hydrogen atom, instead of oxygen gas

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Glycolysis All Cells Use Glycolysis  Every living creature is capable of carrying out glycolysis. - Most present-day organisms can extract considerably more energy from glucose through aerobic respiration. 1 glucose = 36 ATP If no oxygen is present, NAD must be recycled by some other means:  Fermentation - Lactic Acid Fermentation - Bacteria that make cheese, pickles, sour cream - Alcoholic Fermentation  Yeast, bacteria

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Energy Storage Proteins, fats, and other organic molecules are also metabolized for energy.  Amino acids of proteins are first deaminated while fats undergo  -oxidation.

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Copyright © McGraw-Hill Companies Permission required for reproduction or display