1. Copyright Pearson Prentice Hall
Biology
Copyright Pearson Prentice Hall

2. Energy and Life EQ What are photosynthesis and cellular respiration?
Photo Credit: ©Stone
Copyright Pearson Prentice Hall

3. Autotrophs and Heterotrophs
Living things need energy to survive.
This energy comes from food. The energy in most food comes from the sun.
Where do plants get the energy they need to produce food?
Copyright Pearson Prentice Hall

4. Autotrophs and Heterotrophs
Plants and some other types of organisms are able to use light energy from the sun to produce food are called autotrophs.
Organisms that obtain their energy from the food they eat are called heterotrophs.
Copyright Pearson Prentice Hall

5. Chemical Energy and ATP
Energy comes in many forms including light, heat, and electricity.
Energy can also be stored in chemical compounds.
Copyright Pearson Prentice Hall

6. Chemical Energy and ATP
An important chemical compound that cells use to store and release energy is adenosine triphosphate, abbreviated ATP.
ATP is used by all types of cells as their basic energy source.
Copyright Pearson Prentice Hall

7. Chemical Energy and ATP
ATP consists of:
adenine
ribose (a 5-carbon sugar)
3 phosphate groups
Adenine
Ribose
3 Phosphate groups
ATP is used by all types of cells as their basic energy source.
ATP
Copyright Pearson Prentice Hall

8. Chemical Energy and ATP
Storing Energy
ADP has two phosphate groups instead of three.
A cell can store small amounts of energy by adding a phosphate group to ADP.
ATP
ADP
Energy +
Energy
Adenosine Triphosphate (ATP)
Adenosine Diphosphate (ADP) + Phosphate
Partially charged battery
Fully charged battery
Copyright Pearson Prentice Hall

9. Chemical Energy and ATP
Releasing Energy
Energy stored in ATP is released by breaking the chemical bond between the second and third phosphates.
2 Phosphate groups P
ADP
Copyright Pearson Prentice Hall

10. Chemical Energy and ATP
The energy from ATP is needed for many cellular activities, including active transport across cell membranes, protein synthesis and muscle contraction.
ATP’s characteristics make it exceptionally useful as the basic energy source of all cells.
Copyright Pearson Prentice Hall

11. Using Biochemical Energy
Most cells have only a small amount of ATP, because it is not a good way to store large amounts of energy.
Cells can regenerate ATP from ADP as needed by using the energy in foods like glucose.
Copyright Pearson Prentice Hall

12. Copyright Pearson Prentice Hall
The key cellular process identified with energy production is photosynthesis. Photosynthesis is the process in which green plants use the energy of sunlight to convert water and carbon dioxide into high-energy carbohydrates and oxygen.
Copyright Pearson Prentice Hall

13. The Photosynthesis Equation
The equation for photosynthesis is:
CO2 + H2O C6H12O6 + O2
carbon dioxide + water sugars + oxygen
Light
Light
Copyright Pearson Prentice Hall

14. The Photosynthesis Equation
Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen.
Copyright Pearson Prentice Hall

15. The Photosynthesis Equation
Light energy
H2O
Light-Dependent Reactions (thylakoids) O2
ADP NADP+
ATP NADPH
Photosynthesis is a series of reactions that uses light energy from the sun to convert water and carbon dioxide into sugars and oxygen.
CO2 + H20
Sugar
Calvin Cycle (stroma)
Copyright Pearson Prentice Hall

16. Copyright Pearson Prentice Hall
Light and Pigments
Light and Pigments
How do plants capture the energy of sunlight?
In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll.
Copyright Pearson Prentice Hall

17. Copyright Pearson Prentice Hall
Light and Pigments
Plants gather the sun's energy with light-absorbing molecules called pigments.
The main pigment in plants is chlorophyll.
There are two main types of chlorophyll:
chlorophyll a
chlorophyll b
Copyright Pearson Prentice Hall

18. Copyright Pearson Prentice Hall
Light and Pigments
Chlorophyll does not absorb light will in the green region of the spectrum. Green light is reflected by leaves, which is why plants look green.
100 80 60 40 20
Chlorophyll b
Estimated Absorption (%)
Chlorophyll a
Photosynthesis requires light and chlorophyll. In the graph above, notice how chlorophyll a absorbs light mostly in the blue-violet and red regions of the visible spectrum, whereas chlorophyll b absorbs light in the blue and red regions of the visible spectrum.
Wavelength (nm)
Copyright Pearson Prentice Hall

19. Copyright Pearson Prentice Hall
9-1 Chemical Pathways
Food serves as a source of raw materials for the cells in the body and as a source of energy.
Animal Cells
Animal
Mitochondrion
Plant
Photo Credits: left: ©Bob Gurr/DRK Photo; middle bottom: ©John Durham/Science Photo Library/Photo Researchers, Inc. ; middle top: ©Ron Boardman/Stone; right: ©Keith Porter/Photo Researchers, Inc.
Plant Cells
Copyright Pearson Prentice Hall

20. Overview of Cellular Respiration
Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.
Copyright Pearson Prentice Hall

21. Overview of Cellular Respiration
The equation for cellular respiration is:
6O2 + C6H12O6 → 6CO2 + 6H2O + Energy
oxygen + glucose → carbon dioxide + water + Energy
Copyright Pearson Prentice Hall

22. Overview of Cellular Respiration
Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place in the mitochondria.
Glycolysis
Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place inside the mitochondria.
Cytoplasm
Mitochondrion
Copyright Pearson Prentice Hall

23. Copyright Pearson Prentice Hall
Glycolysis
ATP Production
At the beginning of glycolysis, the cell uses up 2 molecules of ATP to start the reaction.
2 ATP
2 ADP
4 ADP
4 ATP
Glycolysis is the first stage in cellular respiration. During glycolysis, glucose is broken down into 2 molecules of pyruvic acid.
Glucose
2 Pyruvic
acid
Copyright Pearson Prentice Hall

24. Copyright Pearson Prentice Hall
Glycolysis
Four molecules of ATP are produced.
This gives the cell a net gain of 2 ATP molecules.
2 ATP
2 ADP
4 ADP
4 ATP
Glucose
2 Pyruvic
acid
Copyright Pearson Prentice Hall

25. Copyright Pearson Prentice Hall
Glycolysis
One reaction of glycolysis removes 4 high-energy electrons, passing them to an electron carrier called NAD+.
Each NAD+ accepts a pair of high-energy electrons and becomes an NADH molecule.
2 ATP
2 ADP
4 ADP
4 ATP
Glucose
2NAD+
2 Pyruvic
acid 2
Copyright Pearson Prentice Hall

26. Copyright Pearson Prentice Hall
Glycolysis
The Advantages of Glycolysis
The process of glycolysis is so fast that cells can produce thousands of ATP molecules in a few milliseconds.
Glycolysis does not require oxygen.
Copyright Pearson Prentice Hall

27. 9-2 The Krebs Cycle and Electron Transport
Oxygen is required for the final steps of cellular respiration.
Because the pathways of cellular respiration require oxygen, they are aerobic.
During the Krebs cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions.
The energy tally from 1 molecule of pyruvic acid is
4 NADH
1 FADH2
1 ATP
Copyright Pearson Prentice Hall

28. Copyright Pearson Prentice Hall
The Totals
The Totals
Glycolysis produces just 2 ATP molecules per molecule of glucose.
The complete breakdown of glucose through cellular respiration, including glycolysis, results in the production of 36 molecules of ATP.
Copyright Pearson Prentice Hall

29. Copyright Pearson Prentice Hall
The Totals
The complete breakdown of glucose through cellular respiration, including glycolysis, results in the production of 36 molecules of ATP.
Copyright Pearson Prentice Hall

30. Comparing Photosynthesis and Cellular Respiration
The energy flows in photosynthesis and cellular respiration take place in opposite directions.
Copyright Pearson Prentice Hall

31. Comparing Photosynthesis and Cellular Respiration
On a global level, photosynthesis and cellular respiration are also opposites.
Photosynthesis removes carbon dioxide from the atmosphere and cellular respiration puts it back.
Photosynthesis releases oxygen into the atmosphere and cellular respiration uses that oxygen to release energy from food.
Copyright Pearson Prentice Hall

32. Copyright Pearson Prentice Hall
Left Side Activity
Write down the equations for photosynthesis and cellular respiration
Explain how photosynthesis and cellular respiration are related
Copyright Pearson Prentice Hall