1. Transformation of Energy
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Transformation of Energy
Energy is the ability to do work.
Thermodynamics is the study of the flow and transformation of energy in the universe.

2. Laws of Thermodynamics
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Laws of Thermodynamics
First law—energy can be converted from one form to another, but it cannot be created nor destroyed.
Second law—energy cannot be converted without the loss of usable energy.

3. Autotrophs and Heterotrophs
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Autotrophs and Heterotrophs
Autotrophs are organisms that make their own food.
Heterotrophs are organisms that need to ingest food to obtain energy.

4. All of the chemical reactions in a cell
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Metabolism
All of the chemical reactions in a cell
Photosynthesis—light energy from the Sun is converted to chemical energy for use by the cell
Cellular respiration—organic molecules are broken down to release energy for use by the cell

5. ATP: The Unit of Cellular Energy
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP: The Unit of Cellular Energy
ATP releases energy when the bond between the second and third phosphate groups is broken, forming a molecule called adenosine diphosphate (ADP) and a free phosphate group.
ATP

6. All of the energy from the food you eat comes from the sun.
Chapter 8
Cellular Energy
8.1 Formative Questions
All of the energy from the food you eat comes from the sun.
true
false A B
FQ 2

7. Chapter 8
Cellular Energy
8.1 Formative Questions
Which law of thermodynamics explains why the ladybug receives the least amount of usable energy? A B
the first law of thermodynamics
the second law of thermodynamics
FQ 1

8. Why is cellular respiration a catabolic pathway?
Chapter 8
Cellular Energy
8.1 Formative Questions
Why is cellular respiration a catabolic pathway?
Energy is used to form glucose and oxygen.
Energy is converted from water to carbon dioxide.
Energy that is lost is converted to thermal energy.
Energy is released by the breakdown of molecules. A B C D
FQ 3

9. Why is adenosine triphosphate (ATP) such an
Chapter 8
Cellular Energy
8.1 Formative Questions
Why is adenosine triphosphate (ATP) such an
important biological molecule?
It captures light energy from the sun.
It is produced in anabolic pathways.
It stores and releases chemical energy.
It converts mechanical energy to thermal energy. A B C D
FQ 4

10. Chapter 8
Cellular Energy
Chapter Assessment Questions
Look at the following figure. Which molecule is released when ATP becomes ADP?
phosphate group
water molecule
ribose sugar
energy cells A B C D
CAQ 3

11. Overview of Photosynthesis
Chapter 8
Cellular Energy
8.2 Photosynthesis
Overview of Photosynthesis
Photosynthesis occurs in two phases.
Light-dependent reactions
Light-independent reactions

12. Phase One: Light Reactions
Chapter 8
Cellular Energy
8.2 Photosynthesis
Phase One: Light Reactions
The absorption of light is the first step in photosynthesis.
Chloroplasts capture light energy.

13. Chloroplast
Organelle that contains green chlorophyll to do photosynthesis.

14. Chloroplast – organelle of photosynthesis
2 outside membranes enclose stroma
Stroma – gelatinous with enzymes, ribosomes, DNA, and grana
Grana – stack of thylakoids
Thylakoid – membrane studded with photosynthetic pigments enclosing thylakoid space

15. Accessory pigments What colors do you see?
Used to illustrate why most leaves are green. This image has several yellow, orange, red, and purple dots mixed in with green. There are so many green pixels that we only see the green. If we took the green away, the dots are more visible against the white background.

16. Pigments Chlorophyll a Accessory pigments
Most abundant photosynthetic pigment in plants, algae, and cyanobacteria
Accessory pigments
Chlorophyll b
Carotenoids
Only absorbed light is photosynthetically active
Absorb red and blue
Reflect green
Accessory pigments extend used range of wavelengths used

17. Chapter 8
Cellular Energy
8.2 Photosynthesis
Electron Transport
Light energy excites electrons in photosystem II and also causes a water molecule to split, releasing an electron into the electron transport system, H+ into the thylakoid space, and O2 as a waste product.

18. Chapter 8
Cellular Energy
8.2 Photosynthesis
The excited electrons move from photosystem II to an electron-acceptor molecule in the thylakoid membrane.
The electron-acceptor molecule transfers the electrons along a series of electron-carriers to photosystem I.

19. Photosystem I transfers the electrons to a protein called ferrodoxin.
Chapter 8
Cellular Energy
8.2 Photosynthesis
Photosystem I transfers the electrons to a protein called ferrodoxin.
Ferrodoxin transfers the electrons to the electron carrier NADP+, forming the energy-storing molecule NADPH.
ATP is also formed during the light reactions.

20. Phase Two: The Calvin Cycle
Chapter 8
Cellular Energy
8.2 Photosynthesis
Phase Two: The Calvin Cycle
In the second phase of photosynthesis, called the Calvin cycle, energy is stored in organic molecules such as glucose.

21. Chapter 8
Cellular Energy

22. Chapter 8
Cellular Energy
8.2 Photosynthesis
Six CO2 molecules combine with six 5-carbon compounds to form twelve 3-carbon molecules called 3-PGA.
The chemical energy stored in ATP and NADPH is transferred to the 3-PGA molecules to form high-energy molecules called G3P.

23. Chapter 8
Cellular Energy
8.2 Photosynthesis
Two G3P molecules leave the cycle to be used for the production of glucose and other organic compounds.
An enzyme called rubisco converts the remaining ten G3P molecules into 5-carbon molecules called RuBP.
These molecules combine with new carbon dioxide molecules to continue the cycle.

24. Alternative Pathways C4 plants CAM plants 8.2 Photosynthesis
Chapter 8
Cellular Energy
8.2 Photosynthesis
Alternative Pathways
C4 plants
CAM plants
All plants use the Calvin cycle (C3 pathway) to make glucose
C3 plants use only the Calvin cycle
About 95% of plant species (peanuts, spinach, trees)
Photorespiration is a problem in hot, dry conditions
Rubisco uses O2 as a substrate (instead of CO2) starting a process that removes already fixed carbon
If stomata kept closed to prevent water loss, O2 builds up and photorespiration increases

25. C4 plants Light and Dark reactions in separate cells Malate
4-carbon compound
1% of plants
Sugarcane, corn, crabgrass

26. CAM plants Crassulacean acid metabolism
Open stomata to fix carbon only at night
Store malate in vacuole
Fix it again in Calvin cycle during the day
Stored malate moves into chloroplast in the same cell
3-4% of plants
Pineapple and cacti
Saves water

27. Photosynthesis Video

28. Chapter 8
Cellular Energy
Chapter Assessment Questions
Look at the following figure. Which part of the chloroplast is a sac-like membrane arranged in stacks?
grana
stroma
thylakoids
Golgi apparatus A B C D
CAQ 1

29. pyruvate is broken down into what compound?
Chapter 8
Cellular Energy
Chapter Assessment Questions
During the Krebs cycle,
pyruvate is broken down
into what compound?
H2O O2 CO
CO2 A B C D
CAQ 2

30. Where in the plant cell does photosynthesis take place?
Chapter 8
Cellular Energy
8.2 Formative Questions
Where in the plant cell does photosynthesis take place?
chloroplasts
Golgi apparatus
mitochondria
vacuoles A B C D
FQ 5

31. Which range of wavelengths is reflected by chlorophylls a and b?
Chapter 8
Cellular Energy
8.2 Formative Questions
Which range of wavelengths is reflected by chlorophylls a and b? nm nm nm A B C
FQ 6

32. Which mechanism of photosynthesis uses
Chapter 8
Cellular Energy
8.2 Formative Questions
Which mechanism of photosynthesis uses
the movement of hydrogen ions (H+) across
a concentration gradient to synthesize ATP?
absorption
chemiosmosis
electron transport
C2 pathway A B C D
FQ 7

33. How are the C4 pathway and the CAM pathway
Chapter 8
Cellular Energy
8.2 Formative Questions
How are the C4 pathway and the CAM pathway
an adaptive strategy for some plants?
They accelerate photosynthesis.
They release more oxygen.
They help the plant conserve water.
They reduce the requirement for ATP. A B C D
FQ 8

34. A B Which metabolic process is photosynthesis? A B
Chapter 8
Cellular Energy
Standardized Test Practice
Which metabolic process is photosynthesis? A B A B
STP 1

35. At the beginning of photosynthesis, which
Chapter 8
Cellular Energy
Standardized Test Practice
At the beginning of photosynthesis, which
molecule is split to produce oxygen (O2) as
a waste product?
CO2
H2O
C6H12O6
3-PGA A B C D
STP 2

36. Which molecule helps provide the energy that drives this cycle?
Chapter 8
Cellular Energy
Standardized Test Practice
Which molecule helps provide the energy that drives this cycle?
3-PGA
CO2
NADPH
rubisco A B C D
STP 3

37. Which product of the Calvin cycle is used for
Chapter 8
Cellular Energy
Standardized Test Practice
Which product of the Calvin cycle is used for
the production of glucose and other organic compounds?
ADP
CO2
G3P
NADP+ A B C D
STP 4

38. Overview of Cellular Respiration
Chapter 8
Cellular Energy
8.3 Cellular Respiration
Overview of Cellular Respiration
Organisms obtain energy in a process called cellular respiration.
The equation for cellular respiration is the opposite of the equation for photosynthesis.

39. Cellular respiration occurs in two main parts. Glycolysis
Chapter 8
Cellular Energy
8.3 Cellular Respiration
Cellular respiration occurs in two main parts.
Glycolysis
Aerobic respiration
Krebs cycle
Electron transport chain

40. Glycolysis does not require oxygen and is therefore anaerobic.
Chapter 8
Cellular Energy
8.3 Cellular Respiration
Glycolysis
Glucose is broken down in the cytoplasm through the process of glycolysis.
Two molecules of ATP and two pyruvate are formed for each molecule of glucose that is broken down.
Glycolysis does not require oxygen and is therefore anaerobic.

41. Glycolysis has a net result of two ATP and two pyruvate.
Chapter 8
Cellular Energy
8.3 Cellular Respiration
Krebs Cycle
Glycolysis has a net result of two ATP and two pyruvate.
Most of the energy from the glucose is still contained in the pyruvate.
The series of reactions in which pyruvate is broken down into carbon dioxide is called the Krebs cycle.

42. Chapter 8
Cellular Energy
8.3 Cellular Respiration
The net yield from the Krebs cycle is six CO2 molecules, two ATP, eight NADH, and two FADH2.

43. Electron Transport Chain
Chapter 8
Cellular Energy
8.3 Cellular Respiration
Electron Transport Chain
Final step and most important step in the breakdown of glucose
Point at which ATP is produced
Produces 32 ATP
The Kreb cycle and ETC occur in the mitochondria of eukaryotes.

44. Anaerobic Respiration
Chapter 8
Cellular Energy
8.3 Cellular Respiration
Anaerobic Respiration
The anaerobic pathway that follows glycolysis
Two main types
Lactic acid fermentation
Alcohol fermentation
Wine and Chocolate
Ethanol
Cellular Respiration

45. Cellular Respiration Video

46. What is the overall purpose of cellular respiration?
Chapter 8
Cellular Energy
8.3 Formative Questions
What is the overall purpose of cellular
respiration?
to make ATP
to process H2O
to store glucose
to deliver oxygen A B C D
FQ 9

47. Which represents the general sequence of cellular respiration?
Chapter 8
Cellular Energy
8.3 Formative Questions
Which represents the general sequence of
cellular respiration?
TCA cycle  chemiosmosis  glycolysis
glycolysis  Krebs cycle  electron transport
electron absorption  catalysis  phosphorylation
aerobic pathway  anaerobic pathway  fermentation A B C D
FQ 10

48. Which stage of cellular respiration is the anaerobic process?
Chapter 8
Cellular Energy
8.3 Formative Questions
Which stage of cellular respiration is the
anaerobic process?
glycolysis
Krebs cycle
electron transport A B C
FQ 11

49. CoA CO2 FADH2 NADH Which molecule generated by the Krebs
Chapter 8
Cellular Energy
8.3 Formative Questions
Which molecule generated by the Krebs
cycle is a waste product?
CoA
CO2
FADH2
NADH A B C D
FQ 12

50. What is the final step of cellular respiration?
Chapter 8
Cellular Energy
Standardized Test Practice
What is the final step of cellular respiration?
O2 and H+ form H2O.
Electrons and H2O generate ATP.
C6H12O6 is broken down into CO2.
NADH and FADH2 gain electrons. A B C D
STP 5

51. an increased demand for ATP
Chapter 8
Cellular Energy
Standardized Test Practice
What prevents pyruvate from entering the Krebs cycle and instead results in this pathway?
a buildup of CO2
a lack of oxygen
an excess of glucose
an increased demand for ATP A B C D
STP 6

52. Which is not a process that occurs in both
Chapter 8
Cellular Energy
Standardized Test Practice
Which is not a process that occurs in both
cellular respiration and glycolysis?
chemiosmosis
electron transport
glycolysis
production of G3P A B C D
STP 7

53. Sources
This PowerPoint presentation is a modified version of a presentation included in a purchased teacher edition supplemental materials packet by McGraw-Hill’s Glencoe Tennessee Biology (material used to modify the presentation was obtained from the same source):
Biggs, Alton. Tennessee Biology. Teacher Ed. T.l.: Glencoe/McGraw-Hill, 2010.