This powerpoint presentation has been adapted from Life 4e-Lewis, Gaffin, Hoefnagels and Parker. Publishers-McGraw-Hill

1. This powerpoint presentation has been adapted from Life 4e-Lewis, Gaffin, Hoefnagels and Parker. Publishers-McGraw-Hill 1998 and Principles of Anatomy and Physiology,Tortora and Grabowski.Publishers- John Wiley & sons, Inc. 2000

2. Chapter 5 HOW CELLS RELEASE ENERGY The last chapter was concerned with how certain cells cyanobacteria, algae, plants) capture energy (photosynthesis). This chapter is concerned with how cells release that energy. The last chapter was concerned with how certain cells cyanobacteria, algae, plants) capture energy (photosynthesis). This chapter is concerned with how cells release that energy.

3. All cells (prokaryotic & eukaryotic) require energy to: combat entropy carry out day-to-day functions repair/replace worn out organelles Reproduce And more What energy rich molecule do cells use?

4. ATP (Adenosine TriPhosphate) Energy currency of cells. ATP molecule contains adenine, ribose & 3 phosphate groups. Wavy lines between phosphate groups represent a significant source of stored energy. When these bonds are broken, energy is released (~ 7 kcal/bond). This energy ca be used by the cell to do work. Organisms require huge amounts of ATP to stay alive. If you ran out of ATP, you would die instantly.ATP molecule contains adenine, ribose & 3 phosphate groups. Wavy lines between phosphate groups represent a significant source of stored energy. When these bonds are broken, energy is released (~ 7 kcal/bond). This energy ca be used by the cell to do work. Organisms require huge amounts of ATP to stay alive. If you ran out of ATP, you would die instantly.

5. ATP Molecule & Energy Each cell has about 1 billion ATP molecules that last for less than one minute Over half (60%) of the energy released from ATP is converted to heat

6. How do cells rebuild ATP? All cells obtain the energy to rebuild their own ATP from nutrients they have either synthesized (autotrophs) or consumed (heterotrophs). Most cells break down nutrients to recycle ATP by either: Cellular respiration (aerobic process) Fermentation (anaerobic process) Aerobic - requiring oxygen (O2) Anaerobic - lacking or not requiring oxygen (O2)Aerobic - requiring oxygen (O2) Anaerobic - lacking or not requiring oxygen (O2)

7. Cellular Respiration (aka. Aerobic Respiration) Biochemical pathways that extract energy from nutrients, in the presence of oxygen gas (O2). Occurs in cells of most eukaryotes & some prokaryotes. Eukaryotes - protists, fungi, plants & animals Prokaryotes - bacteria & archaeaEukaryotes - protists, fungi, plants & animals Prokaryotes - bacteria & archaea

9. In cytoplasm (1) In mitochondria (2, 3 & 4)

10. Mitochondria double-membrane outer is smooth inner is highly folded (cristae) Inner core (matrix) #/cell - A typical liver cell has about 1,700 mitochondria; cells with high energy requirements, such as muscle cells, may have many thousands.#/cell - A typical liver cell has about 1,700 mitochondria; cells with high energy requirements, such as muscle cells, may have many thousands.

11. Glycolysis (�glucose-splitting�) Glucose (6C) is split into two pyruvate/pyruvic acid (3C) molecules. does not require oxygen (gas O2) Amount of energy harvested from 1 glucose: 2 ATP 2 NADH (actively transported into mitochondria of eukaryotic cells) Pyruvate = pyruvic acid Eukaryotic cells have to use 2 ATP molecules to shuttle these 2 NADHs into mitochondria. Energy stored in the bonds of NADH is used by electron transport chain to produce ATP.Pyruvate = pyruvic acid Eukaryotic cells have to use 2 ATP molecules to shuttle these 2 NADHs into mitochondria. Energy stored in the bonds of NADH is used by electron transport chain to produce ATP.

12. Glycolysis of Glucose Breakdown of six-carbon glucose molecule into 2 three-carbon molecules of pyruvic acid 10 step process occurring in cell cytosol Needs 2 ATP but then produces 4 molecules of ATP Produces 2 NADH molecules as hydrogen carriers If O2 limited in a cell (skeletal muscle) pyruvic acid is converted to lactic acid 80% difuses from cell to blood liver cells remove it from blood & convert it back to pyruvic acid

13. Glycolysis of Glucose

14. 10 Steps of Glycolysis

16. Fermentation Biochemical pathways that extract energy from nutrients, in the absence of oxygen gas (O2). Alcoholic fermentation Pyruvic acid is broken down to ethanol and carbon dioxide. Ex. yeast (used in production of baked goods & alcoholic beverages)

17. Notice that alcoholic fermentation yields only 2 ATPs (from glycolysis).Notice that alcoholic fermentation yields only 2 ATPs (from glycolysis).

18. Lactic acid fermentation Pyruvic acid is broken down to lactic acid. Examples: certain bacteria (used in production of cheese & yogurt) human muscle cells without oxygen gas (O2). Working faster than O2 can be delivered Under �oxygen-debt� conditions (cells are working so strenuously that their production of pyruvic acid exceeds the oxygen supply), human muscle cells revert to lactic acid fermentation to extract energy. If enough lactic acid accumulates, the muscle fatigues & cramps.Under �oxygen-debt� conditions (cells are working so strenuously that their production of pyruvic acid exceeds the oxygen supply), human muscle cells revert to lactic acid fermentation to extract energy. If enough lactic acid accumulates, the muscle fatigues & cramps.

19. Notice that lactic acid fermentation yields only 2 ATPs (from glycolysis).Notice that lactic acid fermentation yields only 2 ATPs (from glycolysis).

20. �MIGHTY� MITOCHONDRIAThe Powerhouse of the Cell LECTURE 16LECTURE 16

21. Generalized Generalized Animal Cell Plant Cell

22. Mitochondria double-membrane outer is smooth inner is highly folded (cristae) Inner core (matrix) #/cell - A typical liver cell has about 1,700 mitochondria; cells with high energy requirements, such as muscle cells, may have many thousands.#/cell - A typical liver cell has about 1,700 mitochondria; cells with high energy requirements, such as muscle cells, may have many thousands.

26. Intermediate Step/Formation of Acetyl Coenzyme A Pyruvic acid enters the mitochondria (MATRIX) pyruvic acid loses a CO2 becoming a 2 carbon fragment (acetyl group) NADH produced 2 carbon fragment (acetyl group) is attached to Coenzyme A to form Acetyl Coenzyme A which enter Krebs cycle

31. The Electron Transport Chain Occurs on Cristae Small amounts of energy released in several small steps Energy used to form ATP by chemiosmosis

32. See BSCS page139

33. Steps in Electron Transport Carriers of electron transport chain are clustered into 3 �complexes� that each act as proton pump (expel H+) electrons are passed between complexes Last complex passes its electrons to the 2H+ and to half of an O2 molecule to form a water molecule (H2O)

34. Chemiosmotic phosphorylation occurring in mitochondria is essentially the same as that occurring in chloroplasts. NADH & FADH2 molecules pass electrons to the ETC. As electrons move down the chain, they release energy which is used to pump protons (H+) out of the mitochondrial matrix & into the intermembrane space. A proton gradient is established. Gradient drives ATP synthesis (protons pass through ATP synthase channels from the intermembrane space to the matrix; ADP is phosphorylated, forming ATP). NOTE: Some insecticides, like 2,4-dinitrophenol, kill by making the inner mitochondrial membrane permeable to protons (destroys the proton gradient). Insect dies when it runs out of ATP. Cyanide & carbon monoxide kill because they block the transfer of electrons to oxygen. Organism dies when it runs out of ATP. Chemiosmotic phosphorylation occurring in mitochondria is essentially the same as that occurring in chloroplasts. NADH & FADH2 molecules pass electrons to the ETC. As electrons move down the chain, they release energy which is used to pump protons (H+) out of the mitochondrial matrix & into the intermembrane space. A proton gradient is established. Gradient drives ATP synthesis (protons pass through ATP synthase channels from the intermembrane space to the matrix; ADP is phosphorylated, forming ATP). NOTE: Some insecticides, like 2,4-dinitrophenol, kill by making the inner mitochondrial membrane permeable to protons (destroys the proton gradient). Insect dies when it runs out of ATP. Cyanide & carbon monoxide kill because they block the transfer of electrons to oxygen. Organism dies when it runs out of ATP.

36. See BSCSpage141

37. 10 Steps of Glycolysis

38. See BSCSpage141

40. See BSCSpage141

41. In cytoplasm (1) In mitochondria (2, 3 & 4)

43. See BSCSpage141

45. Can cells use proteins & lipids to produce energy? Most cells use carbohydrates as the primary source of energy (ATP); however, many cells* can use monomers of proteins & lipids to produce energy. *Neurons cannot utilize energy in proteins & lipids. They must break down carbohydrates to obtain energy. Plant cells use energy derived from lipids to fuel activities such as seed germination.Most cells use carbohydrates as the primary source of energy (ATP); however, many cells* can use monomers of proteins & lipids to produce energy. *Neurons cannot utilize energy in proteins & lipids. They must break down carbohydrates to obtain energy. Plant cells use energy derived from lipids to fuel activities such as seed germination.

46. Proteins are digested to amino acids. To produce ATP from amino acids, cells must convert them into pyruvic acid, acetyl CoA or intermediates of Krebs cycle. Fats are digested to glycerol & fatty acids. Glycerol is converted to pyruvic acid. Fatty acids are converted to acetyl CoA.Proteins are digested to amino acids. To produce ATP from amino acids, cells must convert them into pyruvic acid, acetyl CoA or intermediates of Krebs cycle. Fats are digested to glycerol & fatty acids. Glycerol is converted to pyruvic acid. Fatty acids are converted to acetyl CoA.

47. Arteries Away Veins back Capillaries between- vessels of exchange via diffusion Nutrients Toxins Note: symbolic,arteries and veins both sides of body!

50. Details of Respiratory Membrane

51. Carbohydrate Loading Long-term athletic events (marathons) can exhaust glycogen stored in liver and skeletal muscles Eating large amounts of complex carbohydrates (pasta & potatoes) for 3 days before a marathon maximizes glycogen available for ATP production Useful for athletic events lasting for more than an hour

52. Fermentation Biochemical pathways that extract energy from nutrients, in the absence of oxygen. Alcoholic fermentation Pyruvic acid is broken down to ethanol and carbon dioxide. Ex. yeast (used in production of baked goods & alcoholic beverages)

53. Notice that alcoholic fermentation yields only 2 ATPs (from glycolysis).Notice that alcoholic fermentation yields only 2 ATPs (from glycolysis).

54. Lactic acid fermentation Pyruvic acid is broken down to lactic acid. Examples: certain bacteria (used in production of cheese & yogurt) human muscle cells in oxygen (O2) debt Working faster than O2 can be delivered Under �oxygen-debt� conditions (cells are working so strenuously that their production of pyruvic acid exceeds the oxygen supply), human muscle cells revert to lactic acid fermentation to extract energy. If enough lactic acid accumulates, the muscle fatigues & cramps.Under �oxygen-debt� conditions (cells are working so strenuously that their production of pyruvic acid exceeds the oxygen supply), human muscle cells revert to lactic acid fermentation to extract energy. If enough lactic acid accumulates, the muscle fatigues & cramps.

55. Notice that lactic acid fermentation yields only 2 ATPs (from glycolysis).Notice that lactic acid fermentation yields only 2 ATPs (from glycolysis).

56. ENDOTHERM VS. ECTOTHERMTHE SA/VOL RATIO ALSO INFLUENCES HEAT LOSS AND HEAT CONSERVATION