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Concept 7.1

Concept 7.1. SUNLIGHT POWERS LIFE. OBTAINING FOOD. All organisms need food for energy and building materials Organisms are classified by the ways they obtain food: 1) Autotrophs : make their own food 2) Heterotrophs : get food from others. AUTOTROPHS.

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Concept 7.1

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  2. OBTAINING FOOD • All organisms need food for energy and building materials • Organisms are classified by the ways they obtain food: 1) Autotrophs: make their own food 2) Heterotrophs: get food from others

  3. AUTOTROPHS • Autotrophs: (producers) organisms that make their own food from inorganic molecules • Two methods: • Photosynthesis: use energy in sunlight to make food from water and carbon dioxide (Chapter 8) • Chemosynthesis: use the energy in inorganic compounds to make food

  4. HETEROTROPHS • Heterotrophs: (consumers) unable to make their own food • Must obtain food by eating producers or other consumers • Depend on producers to supply energy and materials for life and growth

  5. ALL CELLS NEED ENERGY • Food molecules are broken down to release energy that cells use to carry out their activities • Cells release chemical energy in food molecules in cellular respiration

  6. CELLULAR RESPIRATION • Cellular respiration: process where cells use oxygen to break down large organic food molecules into simpler molecules • Chemical energy stored in food molecules is converted into another form of chemical energy  ATP (adenosine triphosphate) • Cells in both plants and animals then use ATP as their main energy supply

  7. Both processes recycle common set of chemicals: Water, carbon dioxide, oxygen, glucose Photosynthesis products are reactants for cellular respiration Cellular respiration products are reactants for photosynthesis PHOTOSYNTHESIS & CELLULAR RESPIRATION ARE LINKED


  9. Kinetic energy: energy of motion Potential energy: stored energy due to position or arrangement of molecules REVIEW: FORMS OF ENERGY

  10. Thermal energy: kinetic energy due to random molecular motion Chemical energy: potential energy due to arrangement of atoms within molecules REVIEW: FORMS OF ENERGY

  11. Organic food molecules have a form of potential energy called chemical energy With chemical energy, the potential to perform work depends on the structure of molecules—the arrangement of the atoms Within cells, organic food molecules react with oxygen breaking chemical bonds and releasing energy CHEMICAL ENERGY IN FOOD

  12. RELEASING ENERGY IN FOOD • Cellular respiration: process that cells use to access chemical energy from organic food molecules by slowly releasing it • 40% of the released energy used to form ATP • Remaining released energy “lost” as heat


  14. What does ATP do for you? It supplies YOU with ENERGY! I am SO tired!

  15. USING THE ENERGY IN FOOD • Cell activities do not require all the energy in most food molecules at once • Carbohydrates, fats, and proteins obtained from food do not directly drive the work in your cells • Chemical energy in these compounds must first be converted to energy stored in another molecule  ATP

  16. 3 part molecule Adenine(nitrogenbase) Ribose(5-carbon sugar) Three phosphate groups STRUCTURE OF ATP

  17. HOW ATP RELEASES ENERGY • Potential energy is stored in phosphate bonds of ATP • Energy released whenbond between 2nd and 3rd phosphates is broken • Reaction forms ADP (adenosine diphosphate) and an inorganic phosphate molecule

  18. How do we get energy from ATP? • High- energy bonds between the last two phosphates in ATP are broken.

  19. ATP  ADP + Pi + ENERGY

  20. RELEASING ENERGY IN ATP • ATP molecule contains potential energy, much like a compressed spring • When phosphate group is pulled away, energy is released • Released phosphate group can bond to another molecule and enable it to do work

  21. CELLULAR WORK • Released phosphate group is transferred to another molecule by specific enzymes • Molecule that accepts the phosphate group undergoes a chemical change driving the work done by the cell

  22. Chemical work: building polymers such as proteins Mechanical work: muscle contraction Transport work: solute pumping, endocytosis, or exocytosis TYPES OF CELLULAR WORK

  23. As cells work, ATP is converted to ADP + inorganic phosphate ATP is not lost—it is recyclable ADP is restored to ATP by adding a third phosphate group ATP recycling occurs in mitochondria WHAT HAPPENS TO ADP ?

  24. ATP ADP CYCLE • Cycle occurs very rapidly—a working muscle cell regenerates 10,000,000 ATP molecules per second • The ATP  ADP cycle processes more than 40 kg of ATP each day in a resting adult human


  26. CELLULAR RESPIRATION • Main function of cellular respiration is to produce ATP (energy) for cellular work • Up to 38 molecules of ATP are produced per molecule of glucose when oxygen is available • C6H12O6 + 6 O2  6 CO2 + 6 H2O + 38 ATP Glucose+ 6 Oxygen  6 Carbon Dioxide + 6 Water + 38 ATP

  27. ENERGY RELEASE • Cellular respiration  breaks chemical bonds in glucose molecule slowly(several small steps) • As bonds in glucose are broken, electrons are released • Released electrons “fall” from a high energy state to a lower energy state

  28. Glucose is broken down, releasing electrons Electron carrier molecules called accept high energy “falling” electrons released from glucose “FALLING” ELECTRONS

  29. “FALLING” ELECTRONS • These electrons are passed on to other carriers in a series of transfers electron transport chain • As electrons are transferred, they release small amounts of energy at each step • Released energy is used to make ATP

  30. Cellular respiration is like a step-by-step walk down a staircase


  32. CELLULAR RESPIRATION INVOLVES SEVERAL STEPS • Involves over 25 chemical reactions • Occurs in cytoplasm and mitochondria • Can be divided into three main stages: • 1) Glycolysis • 2) The Krebs cycle • 3) The electron transport chain

  33. STAGES OF CELLULAR RESPIRATION • 1st Stage: Glycolysis - cytoplasm—anaerobic (no O2 needed) • 2nd Stage: Krebs Cycle - mitochondria—aerobic (O2 needed) • 3rd Stage: Electron Transport Chain - mitochondria—aerobic(O2 needed)

  34. STAGE ONE: GLYCOLYSIS • Does NOT require oxygen  anaerobic • First step in cellular respiration • Occurs in cytoplasm • Occurs in ALL organisms • One glucose molecule is split to form two molecules of pyruvic acid

  35. GLYCOLYSIS HAS 2 PHASES • Energy investment phase: 2 ATP needed to start reaction • Energy harvest phase: 4 ATP produced • Net gain: 2 ATP

  36. Envelope has inner and outer membranes Inner membrane: Very highly folded  provides increased surface area Has many sites where cellular respiration can occur Encloses thick fluid matrix STRUCTURE OF MITOCHONDRIA

  37. STAGE TWO: THE KREBS CYCLE • Occurs in matrix of inner mitochondrial membrane • Aerobic – O2 needed • 2 Pyruvic acid  2 Acetyl CoA + 2 CO2 • 2 Acetyl CoA  4 CO2 + 2 ATP • Net result: 2 ATP produced

  38. STAGE THREE: ELECTRON TRANSPORT CHAIN • Occurs on inner mitochondrial membrane • Also called oxidative phosphorylation or chemiosmosis • Aerobic—requires O2 • Electron transport chain works with H+ ions and ATPsynthase (proteins in membrane) to produce ATP • Generates up to 34 ATP per original glucose molecule

  39. MAXIMUM ATP PER GLUCOSE • GLYCOLYSIS = 2 ATP • KREBS CYCLE = 2 ATP • ELECTRON TRANSPORT CHAIN / ATP SYNTHASE = 34 ATP 38 ATP This production results only if O2 is present



  42. FERMENTATION • Process that makes ATP without O2 • ATP produced in fermentation comes entirely from glycolysis • Produces no additional ATP • When O2 is not present there is an overall net gain of 2 ATP per glucose molecule • Two major types of fermentation: • Lactic acid fermentation • Alcoholic fermentation

  43. LACTIC ACID FERMENTATION • Occurs in muscle cells when O2 supply is too low • Cellular respiration continues but fermentation is main ATP source • Produces lactic acid- waste product • Results in muscle soreness after strenuous exercise • Relieved after O2 supply restored

  44. ALCOHOLIC FERMENTATION • Yeast: alcoholic fermentation • Produces ethyl alcohol instead of lactic acid under anaerobic conditions • Used in brewing industry • Released CO2 makes champagne and beer bubbly • Used by bakers to make bread rise

  45. FERMENTATION IN MICROORGANISMS • Fungi & Bacteria: produce lactic acid like muscle cells • Used to flavor yogurt, some cheeses • Other fermentation processes: • Soybeans soy sauce • Cabbage  sauerkraut


  47. WHAT DO I NEED TO KNOW? • Autotrophs vs. heterotrophs • Structure of ATP  adenine, ribose, 3 phosphates • ATP  ADP cycle • Aerobic vs. anaerobic respiration

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