2. More about Cells Prokaryotes and Eukaryotes Organelles of Eukaryotes How do “things” get in and out of cells? – Bouncer – The gatekeeper

3. Movement of Molecules Active Transport PrimarySecondary Passive Transport DiffusionOsmosis Simple Diffusion Facilitated Diffusion

4. 6.1 Energy Is Central to Life

5. Energy Is Central to Life All living things require energy. The sun is the ultimate source of energy for most living things. The sun’s energy is captured on Earth by photosynthesizing organisms, which then pass this energy on to other organisms in the form of food.

6. 6.2 The Nature of Energy

7. What is energy? Energy can be defined as the capacity to bring about movement against an opposing force. - capacity to do work

8. Forms of Energy Energy can be conceptualized as either potential energy, meaning stored energy; or kinetic energy, meaning energy in motion.

9. Energy Conversions  Only ~1% of energy released by the sun that earth receives is captured and converted by plants. Converted into chemical bond energy  What happens to the other 99%? Mostly transformed into heat

10. Thermodynamics - study of energy First Law of Thermodynamics  Energy can never be created or destroyed.  It can only change forms. Second Law of Thermodynamics  Energy transfer will always result in a greater amount of disorder in the universe. (ENTROPY)  Every conversion of energy includes the transformation of some energy into heat.

11. ENTROPY A measure of the amount of disorder in a system The greater the entropy, the greater the disorder.

12. 3. Mechanical energy 2. Heat energy 1. Chemical bond energy heat piston-driven flywheel coalmotion steam Total energy is constant. Entropy increases. Figure 6.2 Transformations of Energy

13. 6.3 How Is Energy Used by Living Things?

14. How Is Energy Used by Living Things? Living things can bring about local increases in order through their metabolic processes. – build up larger molecules from smaller ones – They can, for example, build up more-ordered molecules (starches, proteins) from less ordered molecules (simple sugars, amino acids). However, it takes energy to do this.

15. Product (glycogen) contains more energy than the reactants (glucose) Product (glucose) contains less energy than the reactants (glycogen) endergonic reaction energy in glycogen molecule exergonic reaction energy out glucose molecules Figure 6.4 Energy Stored and Released

16. Endergonic and Exergonic Reactions Exergonic – breaking down molecules releases energy – starting set of molecules (reactants) have more energy than final set of molecules (products) – Energy is created by taking those molecules apart Endergonic –products have more energy than reactants – Energy is used to build molecules Coupled

17. ATP The molecule most often used in living things to power coupled reactions is ATP.

18. 6.4 The Energy Dispenser: ATP

19. Structure of ATP

20. Figure 6.6 The ATP/ADP Cycle

21. Recycling in the Cell ADP + phosphate group + energy = ATP

22. Movie Time https://youtu.be/00jbG_cfGuQ From 1:30 to 3:30

23. © 2011 Pearson Education, Inc. 6.5 Efficient Energy Use in Living Things: Enzymes

24. Enzymes are proteins that initiate and speed up chemical reactions (rate of reaction)

25. Figure 6.8 Enzyme Action – plays a role in metabolic pathways enzyme A enzyme C enzyme B substrates product

26. Movie Time Enzymes: https://youtu.be/tI69AVRW0DUhttps://youtu.be/tI69AVRW0DU

27. 6.6 Enzymes and the Activation Barrier

28. Figure 6.9 Enzymes accelerate chemical reactions by lowering the activation energy (a) Without enzyme lactoseglucose + galactose activation energy without enzyme net energy released from splitting of lactose (b) With enzyme glucose + galactose lactose activation energy with enzyme net energy released lactase

29. Enzymes Accelerate Chemical Reactions Enzymes are catalysts. They bring about a change in their substrates without being chemically altered themselves.

30. Enzymes Accelerate Chemical Reactions Enzymes generally have a pocket into which the substrate fits. This pocket is the active site—that portion of an enzyme that binds with a substrate, thus helping transform it. SUBSTRATE

31. Substrate Binding – a little help from our friends In some cases, substrate binding is facilitated by coenzymes: molecules other than amino acids that facilitate the work of enzymes by binding with them

32. Coenzyme Accessory molecules Bind with enzymes Sit in the active site and chemically attract or repulse substrates Example: B vitamins

33. 6.7 Regulating Enzymatic Activity

34. The rate at which an enzyme catalyzes a reaction is influenced by several chemical and physical factors. 1.Enzyme and substrate concentration 2.Temperature (optimal) 3.pH 4.Inhibitors or activators a.Competitive Inhibition b.Allosteric

35. Enzyme Inhibition: http://youtu.be/PILzvT3spCQ?list=PL88CEDF4EEA6E940B Movie Time

36. Why do some adults get sick when they drink milk?

37. Other Faulty Enzymes PKU Gaucher Disease – Lipids collect on spleen, liver, kidneys Tay Sachs Disease – Enzyme fold incorrectly & doesn’t break down a certain molecule – Damages nervous system