Energy and Metabolism (Bioenergetics)

1. Energy and Metabolism(Bioenergetics) Lecture #5

2. ENERGY • The capacity to do work • All life processes require energy. • Source • Distribution

3. Two Types of Energy 1. Potential energy – stored energy

5. Two Types of Energy 2. Kinetic energy – energy of motion….actually doing something

7. Much of the work of living organisms requires: potential energy kinetic energy Let’s talk about the principles of energy.

8. Laws of Thermodynamics • 1st Law • Energy can neither be created nor destroyed. • It can only be converted from one form to another • Waterfall to electricity • Food to exercise • Energy transfer is not 100%…heat loss

9. Laws of Thermodynamics • 2nd Law • Energy transfer causes things to go from more orderly state to a more disorderly state (entropy). • Disorder is more likely than order.

11. Source of Energy

12. Energy Source • Source is the sun. • How do living things capture the sun’s energy? • Plants, algae and some bacteria capture the sun’s energy. • This process is called photosynthesis.

13. Energy Flow

14. Energy Flow SUN PLANTS HEAT GIRAFFE HEAT LION

15. Plants capture sun’s energy • How do we get energy out of plants and animals? • Input energy (activation energy) • Yield (output energy) • If (output) – (input) = 0 • So….we need to put in less than we get out • How do we do this?

16. Enzymes • All enzymes are proteins (1 exception). • They convert substrate product. • They lower the activation energy.

18. Enzymes Are Catalysts • The process of lowering the activation energy is catalysis. • An example: CO2 + H2O H2CO3 • The enzyme is carbonic anhydrase. • Without vs with enzyme

19. CO2 + H2O H2CO3 • Substrate(s) • Product(s) • So…..how do enzymes do this catalysis?

20. How Do Enzymes Work? • Enzymes are globular proteins.

21. They have active sites – where substrates bind to the enzyme. • Enzymes are specific for substrates.

22. 4..Amino acids in active site bind with substrate. 5. When enzyme binds with substrate, enzyme changes shape – induced fit.

23. 6. One substrate

24. 7. Two substrates CO2 + H2O H2CO3 • Enzyme is carbonic anhydrase. • This enzyme functions to bring the 2 substrates close together to allow efficient transfer of electrons.

25. Factors AffectingEnzyme Activity • Substrate Product Concentration of substrate 2. Factors that affect the enzyme (a protein)

26. Factors that affectthe enzyme molecule • Temperature • pH

28. 3. Inhibitors • Inhibitors – substance that binds to the enzyme to decrease enzyme activity. • Two types of inhibitors • Competitive – binds to enzyme active site • Noncompetitive – binds elsewhere on enzyme

30. 4. Cofactors • Cofactors are located in the active site. • Manganese & zinc are examples • NAD+ -- nicotinamide adenine dinucleotide

31. Nicotinamide Adenine Dinucleotide

32. NAD+ • NAD+ is missing an electron. • Enzyme binds substrate and NAD+. • Enzyme transfers two electrons from substrate to NAD+ • NAD+ NAD (1st electron) • NAD NADH (2nd electron) • Now…..NADH has a greater amount of energy (2e-)….which it can pass on.

33. ATPThe energy currency of life • Adenosine triphosphate • Energy carrying/transferring molecule w/in the cell

34. Structure of ATP

35. Composition of ATP Consists of three components • 5-carbon sugar – ribose

37. Composition of ATP • 5 – carbon sugar – ribose • Adenine (a purine)

39. Composition of ATP • 5-carbon sugar – ribose • Adenine • Triphosphate P – P – P

41. It is the bonds between the phosphates that possess large amount of energy. • When a cell needs energy for some process…. • ATP ADP + Pi + ENERGY • P – P – P P – P + P + ENERGY • The activation energy of catalysis of ATP to ADP is relatively small. • ATP is the universal energy donor.