1. CHAPTER FIVE
About 75% of the energy generated by a car’s engine is lost as heat
You’d have to run 14 miles to burn the calories from one large pepperoni pizza

2. SOME BASIC ENERGY CONCEPTS
Energy makes the world go around
what is energy?
Energy is the capacity to perform work

3. Conservation of Energy
Kinetic energy is energy in motion
Potential energy is energy in storage 2
High potential energy 1
Conversion of
kinetic energy to
potential energy 3
Conversion of
potential energy
to kinetic energy 4
Low potential energy

4. Conservation of Energy
Energy can be converted from one form to another but it cannot be created or destroyed

5. Heat
Heat is
a type of kinetic energy
randomized energy

6. Chemical Energy Chemical energy is a form of potential energy
is found in food, gas, and other fuels

7. Waste products
poor in chemical
energy
Fuel rich in
chemical
energy
Heat
energy
Gasoline
Carbon dioxide
Combustion
Kinetic energy
of movement
Oxygen
Water
(a) Energy conversion in a car

8. Heat
energy
Cell
respiration
Carbon dioxide
Food
Oxygen
Water
Energy for cellular work
(b) Energy conversion in a cell

9. Cell respiration
is the energy-releasing chemical breakdown of fuel molecules

10. Food Calories
A calorie is the amount of energy that raises the temperature of 1 gram of water by 1 degree Celsius

11. 1 Calorie = 1,000 calories
the unit used to measure the energy in food

12. ATP AND CELLULAR WORK
The chemical energy of organic molecules is released in cell respiration to make ATP
This release occurs in the mitochondria

13. ATP (Adenosine TriPhosphate)
The Structure of ATP
ATP (Adenosine TriPhosphate)
adenosine plus three phosphate groups
Energy
Adenosine
Adenosine
Phosphate transferred to other
molecules

14. ENZYMES
Metabolism is defined as all of the chemical reactions that occur in organisms; rate?
Few metabolic reactions occur without the assistance of enzymes

15. Activation Energy Activation energy
the minimum energy required to activate the reaction

16. Enzymes lower the activation energy for chemical reactions
barrier
Enzyme
Reactants
Products
(a) Without enzyme
(b) With enzyme

17. Each enzyme is very selective
Each enzyme fits to one specific substrate
the active site fits to the substrate and the enzyme changes shape slightly; induced fit

18. Enzymes are reusable Substrate (sucrose) 1 2 Active site Enzyme
available with
empty active site
Active site 2
Substrate binds
to enzyme
Enzyme
(sucrase)
Fructose
Glucose 4
Substrate is
converted to
products
Products
are released 3

19. Enzyme Inhibitors Enzyme inhibitors inhibit a metabolic reaction
bind to the active site, as substrate impostors
Substrate
Inhibitor
Substrate
Active site
Active site
Enzyme
Enzyme
(a) Normal enzyme action
(b) Enzyme inhibition by a substrate imposter

20. Passive Transport: Diffusion Across Membranes
Molecules contain heat energy
they vibrate and wander randomly
Diffusion is one result of the movement of molecules
molecules tend to spread into the available space
diffusion is passive transport; no energy is needed

21. Molecules of dye
Membrane
Equilibrium
(a) Passive transport of one type of molecule
Equilibrium
(b) Passive transport of two types of molecules

22. Osmosis and Water Balance in Cells
Osmosis is the passive transport of water across a selectively permeable membrane
Hypotonic
solution
Hypertonic
solution
Isotonic solutions
Sugar molecule
(solute)
Selectively permeable
membrane
Osmosis
(net movement of water)

23. Water Balance in Cells
The survival of a cell depends on its ability to balance water uptake and loss
Animal
cell
Normal
Lysing
Shriveled
Plasma
membrane
Plant
cell
Flaccid (wilts)
Turgid
Shriveled
(a) Isotonic solution
(b) Hypotonic solution
(c) Hypertonic solution

24. Lower solute concentration Higher solute concentration
Active Transport
Active transport requires energy to move molecules across a membrane
Lower solute concentration
Solute
Higher solute concentration

25. Exocytosis and Endocytosis: Traffic of Large Molecules
secretes substances outside of the cell
Outside cell
Plasma
membrane
Cytoplasm
(a) Exocytosis

26. Endocytosis
takes material into the cell
(b) Endocytosis