Metabolism and Energy

1. Metabolism and Energy

2. 5 minute free write Think about the word Metabolism. • What does it mean? • Why is it important to you? • What does it do for you? • Is it a long or short process? • Can it be controlled? • What affects metabolism? • Does metabolism occur anywhere else other than your body?

3. Metabolism • Metabolism is the sum of all chemical reactions that occur in the cell • Catabolism is the process of breaking down compounds into smaller molecules to release energy • Anabolism is the process of using energy to build larger molecules

4. Anabolism  • all the synthesis or "building up" reactions in a cells • results in the creation of organic compounds (proteins, lipids, glycogen) for energy storage, cell growth, repair, reproduction, etc. • requires energy (endergonic) • What are the energy sources?

5. Anabolism Endergonic Decreases entropy

6. Catabolism • organic compounds are broken down to release the energy stored in them • produces energy (exergonic) • ATP can be used for various cell activities, such as biosynthesis, transport, cell division, movement, bioluminescence, but some energy is also lost as heat.

7. Catabolism Exergonic Increases entropy

8. Catabolism • if this process occurs with O2 then it is biological oxidation and the products are CO2, H2O and lots of energy (captured as ATP) • if this process occurs without O2, then it is fermentation and much less energy is produced (still captured as ATP)

9. http://www.nature.com/scitable/topicpage/cell-metabolism-14026182http://www.nature.com/scitable/topicpage/cell-metabolism-14026182

10. Metabolic Pathway • A metabolic pathway is a series of chemical reactions in living cells. • Each reaction is catalyzed by an enzyme

11. Metabolic Pathway • A metabolic pathway may be linear or circular • The product (end substance) of one pathway may be the reactant (starting substance) of another.   • Often reactions in a pathway are reversible.

12. Metabolic Pathways • All pathways have the following participants: • Substrates/reactants - substances that enter the reaction •  Intermediate products - compounds formed between the start and the end of the reaction • Enzymes - proteins that catalyze reactions • Energy carriers - usually ATP.   • End products/metabolites - substances produced at the end of the pathway.

14. Energy • The ability to do work • What kind of “work” are we talking about in biology?

15. Forms of Energy • At the simplest level, energy is classified as: • Kinetic – energy of motion • Potential energy – stored energy in an object at rest • Other forms of energy are really just forms of these two.

17. http://www.physics4kids.com/files/motion_energy.html

18. Forms of energy • Kinetic • Potential • Thermal • Light • Sound • Chemical • Into which of the two main categories would you place the rest?

19. Bond energy • Whenever a chemical bond forms between two atoms, energy is released. • The amount of energy needed to break a bond is the same as the amount of energy released when the bond is formed

20. Bond energy • This amount of energy is called bond energy • Unbonded atoms can be considered to have more chemical energy than any compound http://www.brooklyn.cuny.edu/bc/ahp/LAD/C4d/C4d_bondenergy.html

21. http://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.htmlhttp://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.html

22. http://www.chem.umass.edu/genchem/summer/chem111/111index.htmlhttp://www.chem.umass.edu/genchem/summer/chem111/111index.html

23. Endergonic Reactions • Any reaction that requires the input of energy is endergonic (“inward energy”) • Endergonic reactions do not proceed spontaneously

24. Exergonic Reactions • A chemical reaction that releases energy is exergonic (“outward energy”) • An exergonic reaction can proceed spontaneously

25. http://www.columbia.edu/cu/biology/courses/c2005/lectures/lec7_10.htmlhttp://www.columbia.edu/cu/biology/courses/c2005/lectures/lec7_10.html

26. Thermodynamics • The study of the energy of transformations in a system • There are two laws

27. First Law of Thermodynamics • Energy cannot be created or destroyed, but it can be transformed from one type into another and transferred from one object to another • E.g. the sun’s energy is used to create glucose therefore it is changed into bond energy

28. Enthalpy • ∆H – overall change in energy that occurs in chemical reactions • ∆H+ endothermic (heat is absorbed) • bonds are formed • ∆H- exothermic (heat is released) • Bonds are broken

29. Second Law of Thermodynamics • During any process, the universe tends toward disorder • Entropy (disorder) is always increasing • This law concerns the transformation of energy into unusable heat, or random molecular motion

30. http://quantum-cosmos.com/blog/2011/05/11/entropy-the-mathematical-description-of-inevitable-disorder/http://quantum-cosmos.com/blog/2011/05/11/entropy-the-mathematical-description-of-inevitable-disorder/

31. 2nd Law and biological systems • Organisms are highly ordered – is life an exception to this law? • The second law only applies to closed systems and organisms are not closed systems

33. ATP • In cells, energy from catabolic reactions is used to power anabolic reactions • The source of energy that links these reactions is ATP, adenosine triphosphate • ATP is the major product of most catabolic pathways • ATP is the major source of energy for anabolic pathways

36. Cyclic nature of ATP • The use of ATP in a cell can be thought of as a cycle • Cells use exergonic reactions to provide the energy needed to synthesize ATP from ADP + Pi (inorganic phosphate) then they use the hydrolysis of ATP to provide energy for endergonic reactions http://www.openclipart.org/detail/laurent_cycle_ATP.svg

37. Electron Carriers • Redox reactions play a key role in the flow of energy through cells • Electrons that pass from one atom to another carry energy with them • The reduced form of a molecule carries more energy than the oxidized form

38. Electron Carriers • Electron carriers are compounds that pick up electrons from energy-rich compounds and then donate them to low-energy compounds • An electron carrier is recycled • NAD+ (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) are important electron carriers

39. Electron Carriers • NAD+ and FAD are oxidized forms • NADH and FADH2 are the reduced forms http://bilingualbiology11a.blogspot.com/2010_10_01_archive.html

40. That’s all for today!