1. Chapter 6 Metabolism

2. 6.1 Energy and Metabolism

3. Energy: the capacity to do work
Chemical reactions in a cell require a transfer of energy
Endergonic reactions have products with more energy
Exergonic reactions have products with less energy

4. 6.2 Potential, Kinetic, Free and Activation

5. The energy that fuels most life on Earth comes from the sun
Kinetic energy: the energy of motion
Potential energy: chemical energy is stored in bonds
The change in bond energy minus entropy contribute to a molecule’s free energy (energy available to do work)
Activation energy: minimum energy required to get a chemical reaction started –all reactions require some input

6. 6.3 Laws of Thermodynamics

7. First law of thermodynamics: energy cannot be created or destroyed
Second law of thermodynamics: energy disperses spontaneously
Entropy: measure of how much the energy of a system is dispersed

8. With each energy transfer, some energy
A Energy In
Sunlight reaches environments on Earth.
Producers in those environments capture
some of its energy and convert it to other
forms that can drive cellular work.
producers
B Some of the energy
captured by producers
ends up in the tissues
of consumers.
CONSUMERS
Figure 5.3 {Animated} Energy flows from the environment into living organisms, and then back to the environment. The flow drives a cycling of materials among producers and consumers.
C Energy Out
With each energy transfer, some energy
escapes into the environment, mainly as
heat. Living things do not use heat to drive cellular work, so energy flows through the world of life in one direction overall.

9. 6.4 ATP

10. ATP (adenosine triphosphate) functions as a cofactor in many reactions
Bonds between phosphate groups hold a lot of energy
When a phosphate group is transferred via the process of phosphorylation, energy is transferred along with it

12. Recycling ATP ATP/ADP cycle: cells regenerate ATP
ADP (diphosphate) forms when a phosphate group is removed from ATP
ATP forms as ADP gains a phosphate group

13. 6.5 Enzymes

14. Metabolism requires enzymes
In a process called catalysis, an enzyme reduces the activation energy of a reaction
Enzymes help bring reactants to a transition state by orienting substrates

16. Enzymes recognizes specific substrates (reactants) that are altered in specific ways
Active site: part of the enzyme where substrates binds and reaction occurs

17. substrate
enzyme
enzyme
enzyme
enzyme
product
enzyme
enzyme

18. Metabolic Pathways

19. Enzyme regulation
Series of enzyme-mediated reactions cells build organic molecules
Regulatory molecules bind directly to an enzyme’s active site
Allosteric regulator alters the shape of an enzyme in a way that enhances or inhibits its function