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Cellular Energy

Explore how organisms obtain energy through photosynthesis & cellular respiration. Learn the laws of thermodynamics, metabolism, and the role of ATP in cellular energy. Discover the phases of photosynthesis and the Calvin Cycle in this comprehensive guide.

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Cellular Energy

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  1. Cellular Energy Section 1: How Organisms Obtain Energy Section2: Photosynthesis Section 3: Cellular Respiration

  2. Cellular Energy Section 1 How Organisms Obtain Energy Transformation of Energy • Energy is the ability to do work. • Thermodynamics is the study of the flow and transformation of energy in the universe.

  3. Cellular Energy Section 1 How Organisms Obtain Energy Laws of Thermodynamics • First law—energy can be converted from one form to another, but it cannot be created nor destroyed. • Second law—energy cannot be converted without the loss of usable energy.

  4. Cellular Energy Section 1 How Organisms Obtain Energy Autotrophs and Heterotrophs • Autotrophs are organisms that make their own food. • i.e. Plants, algae • *chemoautotroph: use inorganic substances for source of energy

  5. Cellular Energy Autotrophs and Heterotrophs • Heterotrophs are organisms that need to ingest food to obtain energy. • - i.e. Wolves, ants, cows

  6. Cellular Energy Section 1 How Organisms Obtain Energy ATP: Adenosine Triphosphate (Structure) • ATP is a nucleotide made of an adenine base, a ribose sugar and three phosphate groups • ATP is the most abundant energy carrier molecule in cells

  7. Cellular Energy Section 1 How Organisms Obtain Energy ATP: The Unit of Cellular Energy • ATP releases energy when the bond between the second and third phosphate groups is broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate group. ATP

  8. Cellular Energy Section 1 How Organisms Obtain Energy Metabolism • All of the chemical reactions in a cell • 2 types of metabolic pathways: • Catabolic pathways- release energy by breaking down larger molecules into smaller ones. • Anabolic pathways-use energy released by catabolic pathways to build larger molecules from smaller molecules

  9. Cellular Energy Section 1 How Organisms Obtain Energy Metabolism • All of the chemical reactions in a cell • Photosynthesis—light energy from the Sun is converted to chemical energy for use by the cell • Cellularrespiration—organic molecules are broken down to release energy for use by the cell

  10. Cellular Energy Section 2 Photosynthesis Overview of Photosynthesis • Photosynthesis occurs in two phases. • Light-dependent reactions • Light-independent reactions

  11. Cellular Energy Section 2 Photosynthesis • Light-dependent reactions- light E is converted to chemical E • Inputs: Water, Light • Outputs: Oxygen, energy molecules, small amount of ATP • Light-independent reactions- simple sugar called glucose is produced • Inputs: CO2, energy molecules, small amount of ATP • Outputs: glucose

  12. Cellular Energy Section 2 Photosynthesis

  13. Cellular Energy Section 2 Photosynthesis Phase One: Light Reactions • Chloroplasts preform photosynthesis. • The absorption of light is the first step in photosynthesis.

  14. Cellular Energy Section 2 Photosynthesis Phase One: Light Reactions • Water is broken down to make oxygen • Energy from light & water and H+ ions from water make energy molecules

  15. Cellular Energy Section 2 Photosynthesis Leaves • Stomata are small pores on the leaf that allow water CO2 and oxygen to enter and leave the leaf. They are controlled by Guard cells • Chlorophyll is the green pigment in chloroplasts that absorbs light. Why are leaves green?

  16. Cellular Energy Section 2 Photosynthesis Phase Two: The Calvin Cycle (light independent) • In the second phase of photosynthesis, called the Calvin cycle, energy is stored in organic molecules such as glucose.

  17. Cellular Energy Section 2 Photosynthesis Light independent reactions • Named after Melvin Calvin who worked out the reaction- Calvin Cycle • Takes place in the stroma

  18. Cellular Energy Section 2 Photosynthesis Light independent reactions • Carbon fixation: process where inorganic CO2 is converted into organic molecules • Rubisco is considered to be one of the most important biological enzymes because it converts inorganic CO2 into organic molecules.

  19. Cellular Energy Section 2 Photosynthesis Light independent reactions Summary • Glucose is made from CO2 which is the synthesis part of photosynthesis

  20. Cellular Energy Section 2 Photosynthesis Alternative Pathways (help minimize H2O loss) • C4 plants: • fix CO2 into 4 C cpds instead of 3C cpds. • Try to keep stomata closed during the day to minimize H2O loss, will open to take large amounts of CO2 • Have specialized cells where CO2 enters the Calvin Cycle • CAM plants: • Only allow CO2 to enter at night • And Perform carbon fixation at night and fix it into an acid for use later on.

  21. Cellular Energy Section 3 Cellular Respiration Overview of Cellular Respiration • Organisms obtain energy in a process called cellular respiration. • The equation for cellular respiration is the almost the opposite of the equation for photosynthesis.

  22. Cellular Energy Section 3 Cellular Respiration • Cellular respiration occurs in three main parts. • Glycolysis • Aerobic respiration (requires oxygen) • Anaerobic respiration (no oxygen required)

  23. Cellular Energy Section 3 Cellular Respiration Glycolysis (anaerobic) • Glucose is broken down in the cytoplasm through the process of glycolysis. • Net Result: Two molecules of ATP, two molecules of pyruvate and two energy molecules (NADH) are formed for each molecule of glucose that is broken down.

  24. Cellular Energy Section 3 Cellular Respiration Krebs Cycle (Citric Acid Cycle) -Aerobic • Most of the energy from the glucose is still contained in the pyruvate. • The series of rxns where pyruvate (input) is broken down into CO2 and electron carrier molecules is called the Krebs cycle. • Since there is two pyruvate, there are two turns in the cycle (one pyruvate broken down per turn).

  25. Cellular Energy Section 3 Cellular Respiration • The net yield (output) from the Krebs cycle (Two Turns) is six CO2 molecules, two ATP, energy molecules (eight NADH, and two FADH2).

  26. Cellular Energy Section 3 Cellular Respiration Electron Transport -Aerobic • Point at which the most ATP is produced • Takes place in inner membrane of mitochondria • Final step in the breakdown of glucose • Uses energy molecules produced in the Krebs cycle (NADH & FADH2) to provide the electrons to generate ATP (Input)

  27. Cellular Energy Section 3 Cellular Respiration Electron Transport- Outputs • O2 (input) is the final electron acceptor and combines w/ H+ to make H2O • Produces 32 ATP-34 ATP

  28. Cellular Energy Section 3 Cellular Respiration Anaerobic Respiration (no oxygen) • The anaerobic pathway that follows glycolysis • Two main types • Lactic acid fermentation • Pyruvate (input) is converted into Lactic Acid (output) • Alcohol fermentation • Pyruvate (input) is converted to Ethanol (output)

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