Cellular Energy Production Plant, Bacteria, & Animal Cells

Cellular Comparison: Plants, Animals, Bacteria

Plant Cells & Photosynthesis Process of plants where sunlight energy, water, and carbon dioxide (CO2) create glucose & O2 Contrast with Cellular Respiration (what animal cells do in the mitochondria) where glucose is broken down and oxygen is used as a catalyst to produce energy molecules with water and CO2 as byproducts Chlorophyll in the chloroplasts absorbs red and blue light, but reflects green light—this is why plants appear as green to us

Plant Cells & Photosynthesis Two Stages Light Dependent Reactions per handout Light Independent Reactions per handout Chemical Reaction of Photosynthesis: 6CO2 + Sunlight Energy + 6H2O > C6H12O6 (glucose) + 6O2

Fermentation: Energy Creation Without Oxygen Completed by many levels of organisms: anaerobic bacteria, animal muscle cells, some protozoa Oxygen is not involved in the process, but may be present in some molecules Fermentation happens in animals when the body is depleted of oxygen, but still needs energy for basic body functions: i.e. heart, lungs, brain

Fermentation: 2 parts Part 1: Glycolysis Takes place outside the mitochondria in the cell cytoplasm, most likely by lysosomes Forms 2 molecules of pyruvic acid and 2 molecules of ATP, the molecule of energy

Part 2: Fermentation Action 2 types depending on Organism Alcohol Ferment: Yeasts do this in production of liquor and bread Reaction: Glucose broken down into pyruvic acid which is converted to alcohol, carbon dioxide and ATP (See handout for actual reaction formula) Lactic Acid Ferment: Used in production of cheese, milk, yogurt, Product of many bacterial processes Occurs in muscle cells when body is oxygen depleted; results in cramps Reaction: Glucose broken down into pyruvic acid, which is converted to lactic acid and ATP Lactic acid is processed in liver and converted back to glucose and used as energy (see handout)

Fermentation vs. Cellular Respiration In Fermentation, one glucose molecule is used to create 4 total ATP molecules, but 2 ATP are used to break down glucose, so the net gain is just 2 ATP molecules In Cellular Respiration (with oxygen), one glucose molecule is used to create 40 total ATP molecules, but 2 ATP are used to break down glucose, so the net gain is 38 ATP molecules Obviously, Cellular Respiration is much more efficient for production of ATP energy

Cellular Respiration Completed in several stages in several locations within the cell: within the cytoplasm of the cell, within the spaces of the mitochondria across the walls of the mitochondria

Cellular Respiration: Part 1: Glycolysis Takes place in cytoplasm of cell, most likely within the lysosomes Energy required in this step—2 ATP molecules for each glucose molecule This diagram is more detailed than needed for our study, but provides a good summation of the complexity of the process

Cellular Respiration: Glycolysis continued ADP molecules are reused to produce ATP energy molecules From original single molecule of glucose; 4 ATP energy molecules produced (2 ATP used); net gain 2 ATP molecules Final products: 2 ATP net molecules 2 Pyruvate molecules

Cellular Respiration: Part 2: Prep for Krebs Cycle Takes place in inner compartment of mitochondria—not across the folds, but between the folds of the mitochondria Each pyruvate molecule is converted to a molecule called acetyl-CoA with the other products: 1 molecule of carbon dioxide and 1 NADH molecule (again, don’t get bogged down with the abbreviations of NAD, NADH, etc)

Cellular Respiration: Part 2—Krebs Cycle Takes place between folds of mitochondria Each acetyl-CoA molecule goes through many changes with water infused, many molecules converted, carbon dioxide released Final product is one molecule of ATP per each molecule of acetyl-CoA converted

Cellular Respiration: Part 3 Electron Transport Chain The final step of Cellular respiration takes place throughout and across the walls of the mitochondria This step utilizes the electrons that have been freed during the several previous steps of cell respiration These electrons are used to drive the final oxidation rxn (use of oxygen molecules) that drives the sodium-potassium pump across the mitochondrion walls Final products of the electron transport chain are an additional 34 molecules of ATP energy

Final Totals of ATP Produced per each molecule of Glucose Cellular Respiration Final Totals of ATP Produced per each molecule of Glucose Cycle ATP produced ATP used Glycolysis 4 2 Krebs Cycle 2 Electron Chain 34________________ Totals 40 minus 2 used equals net gain of 38 ATP molecules

Cellular Respiration: Overall diagram of Process

Energy Pathways in Animal Cells See p. 301 Animals use Carbos, Fats, or Proteins as their main source of energy. All nutrients enter the Cellular Resp. process at different stages, but all used in Mitochondria within cells.