Converting Energy Chapter 5 Part 1: Cellular Respiration

Prior Knowledge Metabolism (p.7) Glucose (p.34) Energy and Chemical Reactions (p.38) Enzymes (p. 40 & 41) Mitochondria (p.65) Chloroplast (p.66) Energy flow in Ecosystems (p.345-347) Water and Carbon Cycles (p.351-352) Autotroph & Heterotrophs

Energy and Living Things Energy is the ability to move or change matter (light, heat, chemical, electrical, etc.) Energy can be stored or released by chemical reactions. Energy from the sunlight flows through living systems, from autotrophs to heterotrophs. Cellular respiration and photosynthesis form a cycle because one process uses the products of the other. ATP supplies cells with energy needed for metabolism.

ATP (adenosine triphosphate) Cells need a steady supply of ATP to function ATP is produced through the process of cellular respiration produced in the mitochondria

ATP It is a nucleotide (nitrogen containing base: adenine, a 5 carbon sugar:ribose, phosphate group) with two extra energy-storing phosphate groups

ATP The phosphate groups store energy like a compressed spring does. This energy is released when the bonds that hold the phosphate groups together are broken. The removal of a phosphate group from ATP produces adenosine diphosphate, or ADP. This reaction releases energy in a way that enables the cell to use energy. Cells use the energy released by this reaction to power metabolism.

Tour de France: How do they do it? 5,900 - 9,000 : Calories consumed by a rider per day 2,241 miles: the total distance 42,000: water bottles used by teams in race 3: number of weeks the tour lasts http://www.tourdefrancenews.com/tourdefrance/daily

Major Parts of the Machine Based on: Starr, C. Biology: Concepts and Applications, Brooks/Cole food, water intake oxygen intake elimination of carbon dioxide Digestive System Respiratory System Absorption nutrients, water, salts oxygen carbon dioxide Circulatory System elimination of food residues rapid transport to and from all living cells

Systems involved: Digestive system – nutrient absorption from food Circulatory system – gas exchange Respiratory system – gas exchange

Cellular Respiration : *Process by which cells produce energy (ATP) from breaking down glucose *Reactants: oxygen & glucose *Products: carbon dioxide, water, ATP Enzymes are specialized proteins that catalyse, affect the rate, of metabolic processes Cellular Respiration Equation: enzymes C6H12O6 + 6O2  6CO2 + 6H2O + ATP glucose + oxygen  carbon dioxide + water + ATP (energy)

Stage 1: Glycolysis Can take place with or without oxygen Converts glucose to 2 molecules of pyruvic acid Uses 2 ATP molecules but produces 4 ATP molecules = net gain of 2ATP molecules Occurs in cytoplasm of cell on mitochondrial outer membrane

Cellular Respiration Stage 1:Gycolysis glucose 2 ATP 2 pyruvic acid Oxygen Independent (can take place with without O2)

Stage 2: Oxygen Required Production of ATP Kreb’s Cycle Aerobic reaction oxygen must be present to start cycle 2 pyruvic acids enter mitochondria Pyruvic acid binds with acetyl-CoA Produces CO2 as a waste product

Stage 2: Production of ATP Oxygen required The Electron Transport Chain Aerobic Inner membrane of the mitochondria

Cellular Respiration Stage 2: With Oxygen pyruvic acid +O2 CO2 Krebs cycle, H2O electron transport chain (in mitochondria) 36 ATP (energy) molecules formed

Total ATP production from one molecule of glucose Result of Aerobic Respiration Process Net ATP Glycolysis 2 Kreb’s Cycle 36 Electron Transport Chain Total ATP production from one molecule of glucose 38

Fermentation: Respiration in the absence of Oxygen Breakdown of carbohydrates in the absence of oxygen When there is no O2 available for Kreb’s cycle, cells undergo fermentation Anaerobic process (no oxygen used) ATP is still produced until oxygen returns to cells

Cellular respiration Stage 2: No oxygen present pyruvic acid CO2 alcohol (in yeasts or some bacteria) or lactic acid

Types of Fermentation: Lactic acid fermentation – produces lactic acid as byproduct Lactic acid fermentation by some prokaryotes and fungi is used in the production of foods – cheese and yogurt Alcoholic fermentation – produces ethanol Carbon dioxide released by yeast causes the rising of bread dough and the carbonation of some alcoholic beverages.

More on lactic acid Some cells such as muscle cells revert to fermentation when oxygen is in short supply (exercise). Blood cannot supply O2 fast enough, therefore, they produce ATP without using O2. The product is lactic acid. In high concentrations, lactic acid causes fatigue & muscle failure (sore muscles). Muscle cells will return to normal when O2 is supplied to chemically change lactic acid. There is current research that says that muscle soreness could be more related to actually tears in the muscle tissues and that lactic acid quickly leaves the muscles.

Comparing Anaerobic vs. Aerobic Lactic Acid Fermentation Alcoholic Fermentation Aerobic Respiration Glucose Glycolysis Lactic acid and 2 ATP Carbon dioxide, ethanol, 2 ATP Carbon dioxide, water, and 38 ATP Production of ATP is more efficient in the presence of oxygen!

Electron Transport Chain Glucose making 2 molecules of pyruvic acid in an anaerobic environment Stage 1 GLYCOLYSIS Pyruvic acid is converted to carbon dioxide and water and 36 molecules of ATP are produced Stage 2: O2 present KREB’S CYCLE (CITRIC ACID CYCLE) Electron Transport Chain Pyruvic acid is converted to carbon dioxide and either alcohol or lactic acid Stage 2: No O2 present Fermentation

It is taken to the lungs and exhaled out of the body What happens to the excess CO2 produced in the cell as a waste product of respiration? C6H12O6 + 6O2  6CO2 + 6H2O + ATP It is taken to the lungs and exhaled out of the body

What would happen to a cell if it had no mitochondria? It would not be able to produce energy and would die.