The Working Cell: Energy from Food Chapter 7 The Working Cell: Energy from Food

Do Now What do plants need to make sugar? What do animals get from plants?

Why is the sun important to life? 7.1 Sunlight Powers Life Why is the sun important to life? Food Water Cycle Climate

Autotrophs autotroph: organism that makes its own food: “self-feeder” Inorganic materials --> organic materials photosynthesis: uses the sun’s energy to convert to food Light(energy) + water + CO2 --> sugar + O2 producers: produce organic molecules that serve as food for other organisms in the ecosystem

Heterotrophs heterotrophs: organisms that can’t make food; “other eaters” consumers: must obtain food by eating producers or other consumers depend on producers for energy and materials for life and growth

Cellular Respiration cellular respiration: chemical process that uses oxygen to convert the chemical energy stored in organic molecules into another form (ATP) food into energy C6H12O6 + O2 --> H2O + CO2 + energy

Do Now Take out your homework (7.1 & 7.2 CC) HW: 7.3 CC What is the equation for cellular respiration?

7.2 Food Stores Chemical Energy energy: the ability to perform work kinetic energy: the energy of motion potential energy: energy stored due to an object’s position or arrangement gain potential energy the higher you go against gravity thermal energy: random molecular movement which causes collisions and heat energy used is provided by food

Chemical Energy Chemical energy the potential to perform work is due to the arrangement of atoms within the molecules depends on the structure of the molecules (carbs, fats, and proteins are rich in chemical energy) sugar (high potential)  carbon dioxide + water (kinetic energy)

Cellular Respiration is like a Car Engine high chemical energy = glucose and oxygen (gasoline and oxygen) “exhaust” = carbon dioxide and water 40% from food to work 60% thermal energy as heat = 100W light bulb calorie: amount of energy required to raise the temperature of 1g water by 1 degree Celsius 1000 calories = 1 kcal = C (on food labels)

Do Now Take out your homework 4 people at a time take the survey on the computers in the back http://www.surveymonkey.com/s/59F79KY

7.3 ATP ATP: adenosine triphosphate Adenosine = adenine + ribose Triphosphate = 3 phosphates One phosphate is lost in a chemical reaction ATP --> ADP The molecule that accepts the phosphate undergoes a change (for work)

Work chemical work: building large molecules Ex. Proteins ATP energy for dehydration synthesis links AA mechanical work: contraction of muscle ATP transfers P to proteins --> change shape --> muscle cells contract transport work: pumping solutes (ions) across a cellular membrane P --> change shape

ATP Cycle ATP is continuously converted to ADP Muscle cell recycles all ATP once a minute 10 million spent and regenerated per second

Do Now What is the overall purpose of cellular respiration? Homework: Work on video critique lyrics Questions 1-12 on CR worksheet

Food to Oxygen Relationship of Cellular Respiration to Breathing aerobic: process that requires oxygen ETC Anaerobic: does not require oxygen Glycolysis fermentation

In Cellular Respiration… Oxygen attracts electrons very strongly “electron grubber” Carbon and hydrogen exert much less pull Several carbon-hydrogen bonds in sugar Carbon and hydrogen change partners and bond with oxygen Electrons in these bonds “fall” toward oxygen and release energy Ex. Burning sugar

7.5 CR Converts Energy Mitochondria Envelope of 2 membranes; inner and outer with space Inner membrane encloses thick fluid (matrix) Enzymes and other molecules built into inner membrane Complex folding allows many sites of reactions to maximize ATP production

Metabolism metabolism: a cell’s chemical processes Metabolic Pathway Series of reactions Specific enzymes catalyzes each reaction 3 Stages of CR Glycolysis, Kreb cycle, ETC and ATP synthase

Stage 1: Glycolysis “splitting of sugar” Outside the mitochondria in the cytoplasm 2 ATP molecules split a 6-carbon glucose in half and adds a phosphate to each C-C-C-P Each 3-C molecule transfers electrons and H+ to a carrier molecule NAD+ NAD+ accepts 2 electrons and one H = NADH “payback” = 4 new ATP molecules produced Result is 2 pyruvic acid molecules

Cycle Input Output ATP Glycolysis Glucose Pyruvic acid 2 Krebs Acetyl CoA (from pyruvate) CO2 ETC Electrons, O2 H2O 34 Overall C6H12O6 + O2 CO2 + H2O +38

Stage 2: Krebs Cycle (Hans Krebs) Finishes breakdown of pyruvic acid molecules to CO2 which releases more ATP Enzymes are dissolved in the fluid matrix Pyruvic acid does not take part in the Krebs cycle Diffuses into the mitochondrion and loses a molecule of CO2 Converted to a 2-C compound = acetyl CoA (Acetyl coenzyme A )

Krebs Cycle Steps Acetyl CoA molecules joins a 4-C acceptor molecule Produce 2 more CO2 molecules and an ATP per acetyl CoA NADH and FADH2 trap most of energy The 4-C acceptor regenerates and cycle continues

Cycle Input Output ATP Glycolysis Glucose Pyruvic acid 2 Krebs Acetyl CoA CO2 ETC Electrons, O2 H2O 34 Overall C6H12O6 + O2 CO2 + H2O +38

Stage 3: ETC and ATP Synthase NADH transfers electrons from glucose to ETC Each transfer in the chain releases energy which is used to pump H+ across the membrane Less concentrated to more Stores potential energy ATP synthases: protein structures in mitochondria that act as miniature turbines H+ rush back “downhill” through the ATP synthase Energy used to convert ADP to ATP

Cycle Input Output ATP Glycolysis Glucose Pyruvic acid 2 Krebs Acetyl CoA CO2 ETC Electrons, O2 H2O 34 Overall C6H12O6 + O2 CO2 + H2O +38

Summary of Cellular Respiration

7.6 Fermentation fermentation: process that can make ATP without oxygen (only 2 ATP) anaerobic: environment without oxygen Fermentation makes ATP entirely from glycolysis Not enough oxygen being supplied Produces waste product called lactic acid Temporary build-up results in soreness & fatigue Eventually converts back into pyruvic acid

Fermentation in Microorganisms and plants Yeast is forced to ferment sugar Produces alcohol and CO2, not lactic acid Some fungi and bacteria produce lactic acid Transform milk into cheese and yogurt Oxygen allows most energy from food Much more efficient 38 ATP (w/oxygen) vs. 2 ATP (w/out)