Some Announcements Monday October 6 UW Evening Degree Program Information Table 4-6:00 pm, Hallway, 1st floor, College Center Tuesday, October 7 Eastern WA@ BCC Information Table 10am-1:00pm, Hallway, 1st floor, College Center Wednesday, October 8 Washington State University Advising Appointments Biology and Society: Feeling the Burn When you exercise, Muscles need in order to perform work. Your cells use oxygen to release from the sugar glucose. Appointments are still available! Students interested in WSU should be sure to call 527-3658 or drop by Advising to make an appointment. Wednesday, October 8 Choosing a Major Workshop Students who are beginning the process exploring major options be sure to join Judy Gage and Jenny Mao for this interactive workshop. 1-2:00pm, Club Room Aerobic metabolism Occurs when enough oxygen reaches cells to support needs. Anaerobic metabolism Occurs when the demand for oxygen outstrips the body s ability to deliver it. Aerobic metabolism Occurs when enough oxygen reaches cells to support needs. Anaerobic metabolism Occurs when the demand for oxygen outstrips the body s ability to deliver it. Aerobic metabolism Occurs when enough oxygen reaches cells to support needs. Anaerobic metabolism Occurs when the demand for oxygen outstrips the body s ability to deliver it. Anaerobic metabolism Without enough oxygen, muscle cells break down glucose to produce lactic acid. Lactic acid is associated with the burn associated with heavy exercise. If too much lactic acid builds up, your muscles give out. 1
Energy Flow and Chemical Cycling in the Biosphere Physical conditioning allows your body to adapt to increased activity. Inflow light The body can increase its ability to deliver oxygen to muscles. Loss heat Chemical (food) Long-distance runners wait until the final sprint to exceed their aerobic capacity. Producers Cycling nutrients (plants and other photosynthetic organisms) Fuel molecules in food represent solar. Energy stored in food can be traced back to the sun. Animals depend on plants to convert solar to chemical Consumers. (such as animals) This chemical is in the form sugars and other organic molecules. Decomposers Copyright 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Producers and Consumers Inflow light Loss heat Chemical (food) Producers Cycling nutrients (plants and other photosynthetic organisms) Consumers (such as animals) Decomposers Photosynthesis Uses light from the sun to power a chemical process that makes organic molecules. Occurs in the leaves terrestrial plants. Producers Inflow light Loss heat Chemical (food) Producers (plants and other photosynthetic organisms) Cycling nutrients Biologists refer to plants and other autotrophs as the producers in an ecosystem. Consumers Consumers (such as animals) Decomposers Heterotrophs are consumers, because they eat plants or other animals. Autotrophs Inflow light Are self-feeders. Include plants and other organisms that make all their own organic matter from inorganic nutrients. Loss heat Chemical (food) Producers (plants and other photosynthetic organisms) Cycling nutrients Heterotrophs Consumers (such as animals) Decomposers Are other-feeders. Include humans and other animals that cannot make organic molecules from inorganic ones. Chemical Cycling between Photosynthesis and Cellular Respiration The ingredients for photosynthesis are carbon dioxide and water. CO2 is obtained from the air by a plant s leaves. H2O is obtained from the damp soil by a plant s roots. Chloroplasts rearrange the atoms these ingredients to produce sugars (glucose) and other organic molecules. Oxygen gas is a by-product photosynthesis. 2
Both plants and animals perform cellular respiration. Cellular respiration is a chemical process that harvests from organic molecules. Cellular respiration occurs in mitochondria. Combustion The waste products cellular respiration, CO 2 and H 2 O, are used in photosynthesis. Cellular Respiration Cellular Respiration: Aerobic Harvest Food Energy Cellular respiration Is the main way that chemical is harvested from food and converted to ATP. Is an aerobic process it requires oxygen. Copyright 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Relationship between Cellular Respiration and Breathing Cellular respiration and breathing are closely related. Cellular respiration requires a cell to exchange gases with its surroundings. Breathing exchanges these gases between the blood and outside air. The Overall Equation for Cellular Respiration A common fuel molecule for cellular respiration is glucose. The overall equation for what happens to glucose during cellular respiration Copyright 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings 3
The Role Oxygen in Cellular Respiration During cellular respiration, hydrogen and its bonding electrons change partners. Hydrogen and its electrons go from sugar to oxygen, forming water. Redox Reactions Chemical reactions that transfer electrons from one substance to another are called oxidation-reduction (redox) reactions. Image from Purves et al., Life: The Science Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com) The loss electrons during a redox reaction is called oxidation. The acceptance electrons during a redox reaction is called reduction. Redox Reactions Chemical reactions that transfer electrons from one substance to another are called oxidation-reduction (redox) reactions. Redox Reactions a transfer electrons The loss electrons during a redox reaction is called oxidation. Image from Purves et al., Life: The Science Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com) The acceptance electrons during a redox reaction is called reduction. Why does electron transfer to oxygen release? When electrons move from glucose to oxygen, it is as though they were falling, thus, releasing their potential. NADH and Electron Transport Chains The path that electrons take on their way down from glucose to oxygen involves many steps. This fall electrons releases during cellular respiration. 4
The first step is an electron acceptor called NAD +. The transfer electrons from organic fuel to NAD + reduces it to NADH. The rest the path consists an electron transport chain. This chain involves a series redox reactions. These lead ultimately to the production large amounts ATP. The Metabolic Pathway Cellular Respiration Cellular respiration is an example a metabolic pathway, A series chemical reactions in cells. All the reactions involved in cellular respiration can be grouped into three main stages: Glycolysis The citric acid cycle Electron transport Stage 1: Glycolysis A molecule glucose is split into two molecules pyruvic acid. Glycolysis breaks a six-carbon glucose into two three-carbon molecules. These molecules then donate high electrons to NAD +, forming NADH. Glycolysis makes some ATP directly when enzymes transfer phosphate groups from fuel molecules to ADP. Stage 2: The Citric Acid Cycle The citric acid cycle completes the breakdown sugar. 5
In the citric acid cycle, pyruvic acid from glycolysis is first prepped into a usable form, Acetyl CoA. In the citric acid cycle, pyruvic acid from glycolysis is first prepped into a usable form, Acetyl CoA. The citric acid cycle extracts the sugar by breaking the acetic acid molecules all the way down to CO 2. Stage 3: Electron Transport Electron transport releases the your cells need to make most their ATP. The cycle uses some this to make ATP. The cycle also forms NADH and FADH 2. The molecules electron transport chains are built into the inner membranes mitochondria. The chain functions as a chemical machine that uses released by the fall electrons to pump hydrogen ions across the inner mitochondrial membrane. These ions store potential. When the hydrogen ions flow back through the membrane, they release. The ions flow through ATP synthase. ATP synthase takes the from this flow, and synthesizes ATP. 6
The first step is an electron acceptor called NAD +. The transfer electrons from organic fuel to NAD + reduces it to NADH. The Versatility Cellular Respiration Cellular respiration can burn other kinds molecules besides glucose: The rest the path consists an electron transport chain. This chain involves a series redox reactions. These lead ultimately to the production large amounts ATP. Adding Up the ATP from Cellular Respiration Fermentation: Anaerobic Harvest Food Energy Some your cells can actually work for short periods without oxygen. Fermentation Is the anaerobic harvest food. Fermentation in Human Muscle Cells After functioning anaerobically for about 15 seconds, Muscle cells will begin to generate ATP by the process fermentation. Glycolysis breaks a six-carbon glucose into two three-carbon molecules. These molecules then donate high electrons to NAD +, forming NADH. Fermentation relies on glycolysis to produce ATP. 7
Glycolysis is the metabolic pathway that provides ATP during fermentation. Pyruvic acid is reduced by NADH, producing NAD +, which keeps glycolysis going. In human muscle cells, lactic acid is a by-product. Fermentation in Microorganisms Various types microorganisms perform fermentation. Yeast cells carry out a slightly different type fermentation pathway. This pathway produces CO 2 and ethyl alcohol. The food industry uses yeast to produce various food products. Evolution Connection: Life on an Anaerobic Earth Ancient bacteria probably used glycolysis to make ATP long before oxygen was present in Earth s atmosphere. Glycolysis is a metabolic heirloom from the earliest cells that continues to function today in the harvest food. Copyright 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings 8