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Chapter 8

Chapter 8. Photosynthesis. Autotrophs vs. Heterotrophs. Autotrophs are organisms that can make their own food Use light energy from the sun to produce Plants are an example Heterotrophs cannot use the sun’s energy directly Obtain energy from the foods they eat

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Chapter 8

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  1. Chapter 8 Photosynthesis

  2. Autotrophs vs. Heterotrophs • Autotrophs are organisms that can make their own food • Use light energy from the sun to produce • Plants are an example • Heterotrophs cannot use the sun’s energy directly • Obtain energy from the foods they eat • Animals and mushrooms are examples

  3. Autotrophs vs. Heterotrophs

  4. Adenosine Energy • ATP – Adenosine triphosphate – is the molecule cells use to store and release energy. Be able to draw it. Energy is released when the bond is broken between the last two phosphates. • ADP – Adenosine diphosphate • AMP – Adenosine monophosphate

  5. Energy

  6. Energy • Adding a phosphate group to ADP allows the organism to store energy • ATP is like a fully charged battery • ADP is like a partially charged battery

  7. Energy Energy is used for: • Active transport: Na+ is pumped out and K+ into the cell • Motor proteins that move organelles • Synthesis of proteins, nucleic acids, lipids,… • Produce light (firefly) • Cell reproduction and more

  8. Energy • Glucose is better for long term storage than ATP • A single molecule of glucose stores 90 times the chemical energy of a molecule of ATP • Most cells only have a small amount of ATP, only enough to last for a few seconds of activity

  9. What is Photosynthesis? • Photosynthesis is the process in which light, water, and carbon dioxide (CO2) is made into sugar and oxygen (O2) • Carbon dioxide + water sugar + oxygen • 6CO2+ 6H2O C6H12O6+ 6O2

  10. Photosynthesis • Chlorophyll a and Chlorophyll b are pigments in the chloroplast that absorb light of the visible spectrum, except for green light. They reflect green, thus the leaf looks green.

  11. Photosynthesis • Photosynthesis takes place in the chloroplasts • Chloroplasts have stacks of thylakoids (saclike photosynthetic membranes) • Proteins in thylakoids organize chlorophyll and other pigments into photosystems, which are the light-collecting units

  12. Light-dependent reactions • Take place in the thylakoid membranes • Convert light energy to ATP and NADPH • Split H2O and release O2 • Electron transport chain connects the two photosystems to make an H+ gradient across the thylakoid membrane (ATP synthase uses this force to make ATP). Uses a proton (H+) pump.

  13. Light-dependent reactions

  14. Calvin cycle reactions • Take place in the stroma • Use ATP and NADPH to convert CO2 to sugar • Return ADP, inorganic phosphate, and NADP+ to the light reactions

  15. Calvin cycle reactions

  16. Photosynthesis

  17. Factors affecting photosynthesis • Water (required raw material) • Plants in dry climates have a waxy coating to prevent water loss • CO2concentration (required raw material) • Temperature: enzymes function best between 0o C and 35oC • Light intensity • Plants can reach a maximum rate of photosynthesis with light intensity (varies between plant type)

  18. Chapter 9 Cellular Respiration

  19. Chemical Energy • How much energy is in food? • One molecule of glucose contains 3811 calories of heat energy • A calorie is the amount of energy needed to raise the temperature of one gram of water one degree Celsius • The Calorie (food labels) is actually 1000 calories

  20. Chemical Energy • The beginning of turning food into energy is glycolysis (produces small amount of energy) • If oxygen is present 2 other pathways occur to produce more energy • If oxygen is not present, 1 different pathway occurs

  21. Energy Pathways • Aerobic – requires oxygen • Also called cellular respiration • Anaerobic – does not need oxygen • Fermentation – name for anaerobic pathway following glycolysis (if oxygen is not present). (The term fermentation includes glycolysis).

  22. What is Cellular Respiration? • Cellular Respiration (video) • Cellular respiration - the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen. • Glucose + oxygen  carbon dioxide + water + energy • C6H12O6 + 6O2 6CO2 + 6H2O + ATP

  23. What is Cellular Respiration? Oxygen Water Carbon dioxide Carbon dioxide

  24. Cellular Respiration • Steps of cellular respiration: • Glycolysis – one glucose is broken in half to make 2 pyruvic acids. Anaerobic. Occurs in cytoplasm. • Krebs cycle – pyruvic acid is broken down into CO2 and energy. Aerobic. Occurs in mitochondrion. Also called citric acid cycle. • Electron transport chain – using a series of proteins, the electrons from the Krebs Cycle and glycolysis to convert ADP to ATP.

  25. Glycolysis • NADH passes energy from glucose to the electron transport chain

  26. Energy Pathways • Aerobic – requires oxygen • Also called cellular respiration • Anaerobic – does not need oxygen • Fermentation – name for anaerobic pathway following glycolysis (if oxygen is not present). (The term fermentation includes glycolysis).

  27. Fermentation • Two types of fermentation: • Alcoholic fermentation: yeasts and some bacteria Pyruvic acid + NADH  alcohol + CO2 + NAD+ • Lactic acid fermentation: most organisms including us and many bacteria • Pyruvic acid + NADH  lactic acid + NAD+ • Both processes regenerate NAD+

  28. Lactic Acid Fermentation

  29. Kreb’s Cycle and ETC • During the Kreb’s cycle pyruvic acid is down into carbon dioxide • Occurs in the mitochondrion • NADH and ATP is produced • In the electron transport chain (ETC) high energy electrons (NADH, FADH2) is converted into ATP • Hydrogen ions are pumped across membrane • ATP synthase – enzyme (protein) that makes ATP using H+ gradient

  30. Cellular Respiration • 1 glucose results in the production of 36 ATP net • 34 more ATP than anaerobic processes • 38% of the total energy in glucose, the other 62% is “lost” through heat • More efficient than an automobile (25%-30%) 70-75% is lost to heat

  31. Energy Pathway Glycolysis Oxygen No Oxygen Anaerobic respiration Aerobic respiration Cellular respiration Fermentation 2 ATP, lactate or alcohol and CO2 36 ATP

  32. Cellular Respiration

  33. Cellular Respiration

  34. Energy Pathway Comparing photosynthesis, cellular respiration, & fermentation:

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