1. ENERGY& METABOLISM

2. ENERGY Energy is the capacity to do work
Energy exists in multiple forms
Light
Heat
Electricity
Chemical bond energy
Etc.
These various types of energy can be places into two groups
Kinetic energy
Potential energy

3. KINETIC ENERGY “Energy of motion” Anything that moves possesses kine
e.g., Heat, light, balls on a pool table, flowing water, flowing electrons, etc.

4. POTENTIAL ENERGY “Energy of location or structure” “Stored energy”
Resting objects may still possess energy
e.g., A rock at the top of a hill, chemical bond energy

5. Potential Energy Diagram: shows changes in potential energy during a chemical reaction. Activation Energy EA Transition state Exergonic

7. THERMODYNAMICS “Energy cannot be created or destroyed”
First Law of Thermodynamics
(The Law of Conservation of Energy)
“Energy cannot be created or destroyed”
“The total amount of energy in the universe is constant”

8. THERMODYNAMICS Energy cannot be created or destroyed
However, it can be converted from one form to another
What energy transformations are taking place here?

9. THERMODYNAMICS
If energy cannot be created or destroyed, why do living things need continual inputs of energy?

10. THERMODYNAMICS The Second Law of Thermodynamics
“Every energy transformation makes the universe more disordered”
Entropy is a measure of this disorder or randomness
“Every energy transformation increases the entropy of the universe”
“When energy is converted from one form to another, some fraction of the potentially usable energy is lost”
Not destroyed, but converted to entropy

11. THERMODYNAMICS I weighed eight pounds and change at birth
I weigh slightly more than eight pounds now
I have increased in order and complexity
Isn’t this counter to the Second Law?

12. THERMODYNAMICS The Second Law of Thermodynamics
Note that we have talked about the universe as a whole, not each individual part of the universe
The universe is a “closed system”
No energy enters or leaves
In a closed system, entropy increases

13. THERMODYNAMICS The Second Law of Thermodynamics
You, as an individual, can increase in order
You do so at the expense of your environment
Overall, the net change in you and in your environment is an increase in disorder
You + environment = a closed system

14. THERMODYNAMICS Certain events occur spontaneously, while others do not
Spontaneous processes occur (once initiated) without outside help
e.g., Water flows downhill, not uphill
How can we explain this?

15. THERMODYNAMICS
The free energy released in spontaneous processes can be harnessed to do work

16. THERMODYNAMICS What energy transformations are occurring here?
What is the spontaneous process?
Is work being done?

17. CHEMICAL REACTIONS Some chemical reactions release free energy
Spontaneous reactions
Exergonic reaction / Exothermic
Some chemical reactions require free energy in order to proceed
Non-spontaneous reactions
Endergonic reaction /Endothermic
The energy released in exergonic reactions can be used to drive endergonic reactions

18. NEED FOR ENERGY
The environment within a cell is highly organized and separate from the external environment
Maintaining this ordered environment costs energy
Many processes within a cell require energy
The requirement for energy is a unifying feature of life
Many organisms extract energy from food via aerobic cellular respiration

19. Metabolism: the sum of all the anabolic(energy storing) and all the catabolic activities(energy releasing) in the cell
Identify each of the following activities as either anabolic or catabolic:
(a) protein synthesis
(b) digestion
(c) DNA synthesis
(d) photosynthesis
(e) cellular respiration

20. CELLULAR RESPIRATION
Cellular Respiration is the controlled breakdown of glucose -catabolic
CR involves a series of chemical reactions that release free energy
Exergonic reactions/Exothermic
spontaneous
This free energy is used for cellular work

21. Redox Reactions:
Cellular respiration is also know as the “Oxidation of Glucose”
Oxidation is a chemical reaction in which an atom loses one or more electrons.
Lost electrons must have somewhere to go
Reduction is a chemical reaction in which an atom gains one or more electrons.
A redox reaction - oxidation coupled with reduction!

22. Free energy in the body =ATP
ATP couples of energy-releasing (exergonic) reactions to energy-requiring (endergonic) reactions

23. ATP CYCLE ATP and ADP are readily interconverted
ATP  ADP releases energy *
ADP  ATP requires energy **

24. The hydrolysis of the terminal phosphate of ATP in a living cell yields and energy value ~54 kJ/mol

25. ATP CYCLE - phosphorylation
Energy-releasing reactions store energy as ATP ADP  ATP
Energy-requiring reactions receive energy from ATP ATP  ADP

26. IS THERE ENOUGH ENERGY TO RUN ALL METABOLIC PROCESSES IN A CELL??
WHAT HAPPENS TO THE ENTROPY PRODUCED IN ALL THE CHEMICAL CONVERSIONS IN A CELL?? IN A BODY??

27. The laws of thermodynamics define which
reactions are spontaneous and which are not…
Some reactions are spontaneous but occur at nearly imperceptibly slow rates
Too slow to sustain life
Enzymes can increase the rate of chemical reactions by more than x