1. KEY CONCEPT All cells need chemical energy.

2. The chemical energy used for most cell processes is carried by ATP
Adenosine Triphosphate
adenine (nitrogen base)
Ribose (sugar)
Three phosphate groups 2

3. The chemical energy used for most cell processes is carried by ATP.
Molecules in food store chemical energy in their bonds.
Starch molecule
Glucose molecule

4. Energy is released when a phosphate group is removed.
ATP transfers energy from the breakdown of food molecules to cell functions.
Energy is released when a phosphate group is removed.
ADP is changed into ATP when a phosphate group is added.
phosphate removed

5. Adenosine diphosphate (ADP) is a lower energy molecule that is created by the removal of the phosphate group.

6. Carbohydrates are the most common molecule to be broken down for ATP
- 36 ATP from 1 glucose
Fats store the most energy.
80 percent of the energy in your body
Proteins are least likely to be broken down to make ATP.
amino acids not usually needed for energy

7. Organisms break down carbon-based molecules to produce ATP.
Plants and animals use ATP for chemical reactions
Plants are autotrophs (make their own carbohydrates)
Animals are heterotrophs (consume carbohydrates)
If plants didn’t have
Mitochondria, they
could make food, but
wouldn’t be able to use
it!

8. A few types of organisms do not need sunlight and photosynthesis as a source of energy.
Some organisms live in places that never get sunlight.
In chemosynthesis, chemical energy is used to build carbon-based molecules.
similar to photosynthesis
uses chemical energy instead of light energy

9. In photosynthesis, organisms make their own food using solar energy.

10. Photosynthetic organisms are producers.
Producers (Autotrophs) make their own source of chemical energy.
Plants use photosynthesis and are producers.
Photosynthesis captures energy from sunlight to make sugars. 10

11. KEY CONCEPT The overall process of photosynthesis produces sugars that store chemical energy.11

12. Chlorophyll is a molecule that absorbs light energy.
chloroplast
leaf cell
leaf
In plants, chlorophyll is found in organelles called chloroplasts.

13. Photosynthesis in plants occurs in chloroplasts.
Photosynthesis takes place in two parts of chloroplasts.
grana (stacks of thylakoids)
Stroma (fluid around the grana)
chloroplast
stroma
grana (thylakoids)

14. The light-dependent reactions capture energy from sunlight.
take place in thylakoids
water and sunlight are needed
chlorophyll absorbs energy
energy is transferred along thylakoid membrane then to light-independent reactions
oxygen is released 14

15. The light-independent reactions make sugars.
take place in stroma
needs 6 carbon dioxide molecules from atmosphere
use energy to build a sugar in a cycle of chemical reactions 15

16. The equation for the overall process is:
6CO2 + 6H2O  C6H12O6 + 6O2
sunlight
C6H12O6
granum (stack of thylakoids)
thylakoid
sunlight
1 six-carbon sugar
6H2O
6CO2
6O2
chloroplast 1 2 4 3
energy
stroma (fluid outside the thylakoids)

17. Chlorophyll is the main pigment in plants
Green light is reflected

18. Chlorophyll is the main pigment in plants
Chlorophyll a absorbs violet and red light
Chlorophyll b absorbs blue and red

19. Other pigments
Carotene (Xanthophyll)

20. Light Dependent Reaction
The light-dependent reactions include groups of molecules called photosystems.

21. Photosystem II captures and transfers energy.
chlorophyll absorbs energy from sunlight
energized electrons enter electron transport chain
water molecules are split
oxygen is released as waste
hydrogen ions are transported across thylakoid membrane

22. Photosystem I captures energy and produces energy-carrying molecules.
chlorophyll absorbs energy from sunlight
energized electrons are used to make NADPH (e carrier)
NADPH is transferred to light-independent reactions

23. The light-dependent reactions produce ATP.
hydrogen ions flow through a channel in the thylakoid membrane
ATP synthase attached to the channel makes ATP

24. Calvin cycle (dark reaction)
Light-independent reactions occur in the stroma and use CO2 molecules.

25. A molecule of glucose is formed as it stores some of the energy captured from sunlight.
carbon dioxide molecules enter the Calvin cycle
energy is added and carbon molecules are rearranged
some molecules are made into sugar
other molecules stay in cycle.