Monday October 6 UW Evening Degree Program Information Table 4-6:00 pm, Hallway, 1st floor, College Center Tuesday, October 7 Eastern BCC Information Table 10am-1:00pm, Hallway, 1st floor, College Center Wednesday, October 8 Washington State University Advising Appointments Appointments are still available! Students interested in WSU should be sure to call or drop by Advising to make an appointment. Wednesday, October 8 Choosing a Major Workshop Students who are beginning the process of exploring major options…be sure to join Judy Gage and Jenny Mao for this interactive workshop. 1-2:00pm, Club Room Some Announcements

Biology and Society: Feeling the Burn –When you exercise, Muscles need energy in order to perform work. Your cells use oxygen to release energy from the sugar glucose.

–Aerobic metabolism Occurs when enough oxygen reaches cells to support energy 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 energy 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 energy 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.

–Physical conditioning allows your body to adapt to increased activity. The body can increase its ability to deliver oxygen to muscles. –Long-distance runners wait until the final sprint to exceed their aerobic capacity.

Producers (plants and other photosynthetic organisms) Cycling of nutrients Consumers (such as animals) Decomposers Chemical energy (food) Inflow of light energy Loss of heat energy Energy Flow and Chemical Cycling in the Biosphere –Fuel molecules in food represent solar energy. Energy stored in food can be traced back to the sun. –Animals depend on plants to convert solar energy to chemical energy. This chemical energy is in the form of sugars and other organic molecules. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

Producers (plants and other photosynthetic organisms) Cycling of nutrients Consumers (such as animals) Decomposers Chemical energy (food) Inflow of light energy Loss of heat energy Producers and Consumers –Photosynthesis Uses light energy from the sun to power a chemical process that makes organic molecules. Occurs in the leaves of terrestrial plants.

Producers (plants and other photosynthetic organisms) Cycling of nutrients Consumers (such as animals) Decomposers Chemical energy (food) Inflow of light energy Loss of heat energy –Autotrophs Are “self-feeders.” Include plants and other organisms that make all their own organic matter from inorganic nutrients. –Heterotrophs Are “other-feeders.” Include humans and other animals that cannot make organic molecules from inorganic ones.

Producers (plants and other photosynthetic organisms) Cycling of nutrients Consumers (such as animals) Decomposers Chemical energy (food) Inflow of light energy Loss of heat energy –Producers Biologists refer to plants and other autotrophs as the producers in an ecosystem. –Consumers Heterotrophs are consumers, because they eat plants or other animals.

Chemical Cycling between Photosynthesis and Cellular Respiration –The ingredients for photosynthesis are carbon dioxide and water. CO 2 is obtained from the air by a plant’s leaves. H 2 O is obtained from the damp soil by a plant’s roots. –Chloroplasts rearrange the atoms of these ingredients to produce sugars (glucose) and other organic molecules. Oxygen gas is a by-product of photosynthesis.

–Both plants and animals perform cellular respiration. Cellular respiration is a chemical process that harvests energy from organic molecules. Cellular respiration occurs in mitochondria. –The waste products of cellular respiration, CO 2 and H 2 O, are used in photosynthesis.

Combustion

Cellular Respiration

Cellular Respiration: Aerobic Harvest of Food Energy –Cellular respiration Is the main way that chemical energy 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. Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings

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

The Role of 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. –The loss of electrons during a redox reaction is called oxidation. –The acceptance of electrons during a redox reaction is called reduction. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates ( and WH Freeman (

Redox Reactions –Chemical reactions that transfer electrons from one substance to another are called oxidation-reduction (redox) reactions. –The loss of electrons during a redox reaction is called oxidation. –The acceptance of electrons during a redox reaction is called reduction. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates ( and WH Freeman (

Redox Reactions a transfer of electrons

–Why does electron transfer to oxygen release energy? When electrons move from glucose to oxygen, it is as though they were falling, thus, releasing their potential energy. This “fall” of electrons releases energy during cellular respiration.

NADH and Electron Transport Chains –The path that electrons take on their way down from glucose to oxygen involves many steps.

–The first step is an electron acceptor called NAD +. The transfer of electrons from organic fuel to NAD + reduces it to NADH. –The rest of the path consists of an electron transport chain. This chain involves a series of redox reactions. These lead ultimately to the production of large amounts of ATP.

The Metabolic Pathway of Cellular Respiration –Cellular respiration is an example of a metabolic pathway, A series of chemical reactions in cells. –All of 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 of glucose is split into two molecules of pyruvic acid.

–Glycolysis breaks a six-carbon glucose into two three-carbon molecules. These molecules then donate high energy 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 of sugar.

–In the citric acid cycle, pyruvic acid from glycolysis is first “prepped” into a usable form, Acetyl CoA.

–The citric acid cycle extracts the energy of sugar by breaking the acetic acid molecules all the way down to CO 2. The cycle uses some of this energy to make ATP. The cycle also forms NADH and FADH 2.

Stage 3: Electron Transport –Electron transport releases the energy your cells need to make most of their ATP.

–The molecules of electron transport chains are built into the inner membranes of mitochondria. The chain functions as a chemical machine that uses energy released by the “fall” of electrons to pump hydrogen ions across the inner mitochondrial membrane. These ions store potential energy.

–When the hydrogen ions flow back through the membrane, they release energy. The ions flow through ATP synthase. ATP synthase takes the energy from this flow, and synthesizes ATP.

–The first step is an electron acceptor called NAD +. The transfer of electrons from organic fuel to NAD + reduces it to NADH. –The rest of the path consists of an electron transport chain. This chain involves a series of redox reactions. These lead ultimately to the production of large amounts of ATP.

The Versatility of Cellular Respiration –Cellular respiration can “burn” other kinds of molecules besides glucose:

Adding Up the ATP from Cellular Respiration

Fermentation: Anaerobic Harvest of Food Energy –Some of your cells can actually work for short periods without oxygen. –Fermentation Is the anaerobic harvest of food energy.

Fermentation in Human Muscle Cells –After functioning anaerobically for about 15 seconds, Muscle cells will begin to generate ATP by the process of fermentation. –Fermentation relies on glycolysis to produce ATP.

–Glycolysis breaks a six-carbon glucose into two three-carbon molecules. These molecules then donate high energy electrons to NAD +, forming NADH.

–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 of microorganisms perform fermentation. Yeast cells carry out a slightly different type of 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 of food energy. Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings