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Introduction to Cellular Catabolism

Introduction to Cellular Catabolism. Packet #25 Chapter #9. Laws of Thermodynamics. Laws of Thermodynamics. Energy is defined as the capacity to do work and takes a number of forms Light; heat; chemical The 1 st law of thermodynamics

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Introduction to Cellular Catabolism

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  1. Introduction to Cellular Catabolism Packet #25 Chapter #9

  2. Laws of Thermodynamics

  3. Laws of Thermodynamics • Energy is defined as the capacity to do work and takes a number of forms • Light; heat; chemical • The 1st law of thermodynamics • Energy cannot be created or destroyed but changed from one form into another. • When scientists used the term that energy is lost, they are simply stating that it (energy) has been converted into a form which cannot be usefully available for a particular purpose. • The 2nd law of thermodynamics • All natural processes tend to proceed in a direction which increases the randomness or disorder of a system. • All natural processes tend to high entropy.

  4. Metabolism

  5. Energy & Chemical Reactions I • The summation of chemical reactions, via the use of enzymes, that occur within living organisms is called metabolism. • Metabolism is divided is divided into two groups • Anabolism • Catabolism

  6. Energy & Chemical Reactions II • The reactions that make up these processes may either be termed exogonic or exergonic. • Exogonic • Chemical reactions that release energy • Exergonic • Chemical reactions that absorb free energy.

  7. Entropy & Living Organisms • Living organisms maintain low entropy by taking their chemical energy in the form of food. • This food is converted into a form of energy called ATP.

  8. ATP

  9. Functions of ATP • In a metabolically active cell, up to 2 million molecules of ATP are required every second. The ATP is used for a variety of purposes. • Anabolic processes • Active Transport • Movement • Activating reactants • Chemicals often require the addition of phosphate groups from ATP to make them more reactive • Phsophorylation of glucose at the beginning of glycolysis. • Secretion • ATP provides energy for the secretion of cell products.

  10. ATP & Energy Yields • Adenosine triphosphate (ATP) is the form in which energy is temporarily stored from the breakdown of glucose. • The removal of the final phosphate, when changing ATP to ADP, releases 30.6 kJ mol-1 of energy. • ATP + H2O -> ADP + phosphate + 30.6 kJ

  11. Respiration

  12. Types of Respiration • Gaseous Exchange • External respiration (Organ System—Respiratory System) • Processes involved in obtaining oxygen needed for respiration and the removal of gaseous waste such as carbon dioxide. • Cellular Respiration • Internal/tissue • Biological processes which take place within living cells that release energy

  13. Cellular Respiration • Cells require a constant supply of energy to generate and maintain the biological order that keeps them alive. • The energy is derived from the chemical bond energy in food molecules. • Sugars, such as glucose, are particularly important fuel molecules. • Animal cells obtain sugars, and other molecules such as starch that are converted to sugars by eating other organisms. • Heterotrophs

  14. Types of Cellular Respiration • Aerobic Respiration • The oxidation of glucose to produce energy via the use of oxygen. • Sugar molecule is broken down and oxidized to CO2 and H2O. • Energy is derived from the chemical bond energy stored in the sugar. • Anaerobic Respiration • Production of energy without the use of oxygen.

  15. Aerobic Cellular Respiration • Cellular respiration is a complex metabolic process of over 70 reactions that can be divided into three stages • Glycolysis • Kreb’s Cycle (Tricarboxylic acid cycle) • Electron transfer system • Chemiosomosis

  16. Electron Carrier Molecules

  17. Electron (Hydrogen) Carriers • Electron (Hydrogen) carriers are also known as acceptor molecules. • Electrons are collected by electron carriers molecules and passed to electron carriers at lower energy levels. • The electrons are at lower energy levels. • The energy released, as the electrons move to lower energy levels, is used to form ATP from ADP.

  18. Electron (Hydrogen) Carriers II • The electrons are initially part of a hydrogen atom. • Hydrogen coming directly, or indirectly, from glucose. • Hydrogen atom eventually splits into a proton and an electron.

  19. Electron (Hydrogen) CarriersExamples • Nicotinamide adenine dinucleotide • NAD • Nicotinamide adenine dinucleotide phosphate • NADP • Flavine adenine dinucleotide • FAD • Cytochromes

  20. Respiratory Quotients

  21. Respiratory Quotients • A respiratory quotient (RQ) is a measure of the ratio of carbon dioxide evolved to the oxygen consumed: • RQ = CO2evolved / O2consumed • For a hexose sugar, such as glucose, used during cellular respiration, it can be seen from the equation • C6H12O6 + 6O2 6CO2 + 6H2O • The ratio is 6CO2/6O2 = 1.0 • For a fat such as steric acid, RQ = 0.7 • Other RQ’s • Malate = 1.33 • Proteins = 0.9 (varies slightly based on particular protein)

  22. The Role of Vitamin B

  23. Vitamin B • The group of vitamins, called vitamin B, plays a major role in cellular respiration—particularly by acting as coenzymes. • Found in green and leafy vegetables.

  24. Vitamin B

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