1. Photosynthesis

2. Energy and Life Autotrophs – make own energy
Plants
Photosynthesis, chemosynthesis
Heterotrophs – obtain energy from food
Animals
Respiration

3. Chemical Energy and ATP
Principle chemical compounds – ATP – Adenosine Triphosphate
Adenine
5-carbon sugar (ribose)
3 phosphates
ADP – Adenosine Diphosphate
2 phosphates

4. Chemical Energy and ATP
When a cell has energy available it is stored by adding a phosphate group to ADP to make ATP
To release energy, the bond between the 2nd and 3rd phosphates is broken
ATP provides the power for many cellular functions such as active transport, protein synthesis, and muscle contractions.
The characteristics of ATP make it exceptionally useful as the basic energy source for all cells!!!

5. ADP
ATP

6. Investigating P.S. – The Dudes
Jan Van Helmont’s Experiment
Devised an experiment to see if plants grew by taking material out of the soil.
Determined the mass of a pot of dry soil and a small seedling, then planted the seedling in the pot of soil. He watered it regularly. At the end of 5 years, the seedling had grown into a small tree and had gained about 75 kg. The mass of the soil was unchanged. He concluded the mass must have come from the water. The accounts for the “hydrate” portion of the carbohydrate produced by PS.
Helmont didn’t realize that carbon dioxide also played a major role in PS.

7. Investigating P.S. – The Dudes
Joseph Priestly’s Experiment
Priestly took a candle, placed a glass jar over it, and watched as the flame died out. This lead him to believe that something in the air was necessary for the candle to continue burning.
He then found that if he placed a live sprig of mint under the jar and allowed a few days to pass, the candle could be relit and would remain lit for a while.
He concluded that the mint plant produced the substance required for the burning of the candle. He didn’t know it at the time, but what is being released is oxygen.

8. Investigating P.S. – The Dudes
Jan Ingenhousz
Showed the effect observed by Priestly occurred only when the plant was exposed to light.
These experiments, along with others, led to the discovery that plants transform carbon dioxide and water into carbohydrates and oxygen in the presence of light.

9. The Photosynthesis Equation
YOU MUST MEMORIZE THIS!!!!!
sun
Carbon dioxide + water  glucose + oxygen
6 CO H2O  C6H12O6 + 6 O2

10. Light and Pigments
In addition to water and carbon dioxide, PS requires light and chlorophyll (a molecule in chloroplasts).
Energy from the sun travels to Earth in the form of light.
Sunlight is a mixture of different wavelengths of light, many of which are visible and make up the visible spectrum. Different wavelengths are seen as different colors.

11. Light and Pigments
Plants gather the sun’s energy with light-absorbing molecules called pigments. The plants’ principle pigment is chlorophyll.
There are two types of chlorophyll.
Chlorophyll a
Chlorophyll b

12. Light and Pigments
Chlorophyll absorbs light very well in the blue-violet and red regions of the visible spectrum. However it does not absorb light well in the green region of the spectrum.
Green light is reflected by leaves, which is why plants look green.
Plants also contain red and orange pigments such as carotene that absorb light in other regions of the spectrum.

14. Inside the Chloroplast
Location of PS
Contains thylakoids, which are sac-like photosynthetic membranes.
Thylakoids are arranged in stacks called grana.
Proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters known as photosystems, which are light collecting units of the chloroplast.
Two types of reactions in the photosystems:
Light-dependent reactions
Light-independent reactions (aka Calvin Cycle)

15. Chloroplast

17. Electron Carriers
When sunlight excites the e- in chlorophyll, e- gain a great deal of energy.
High-energy e- require a special carrier to move them from chlorophyll to other molecules.
Carrier molecule is a compound that can accept a pair of high-energy e- and transfer them along with most of their energy to another molecule.
Called electron transport
Carriers are called the electron transport chain (ETC)

18. Electron Carriers – NADP+
NADP+ : Nicotinamide adenine dinucleotide phospate
Accepts and hold 2 e- along with H+ ion
This converts NADP+ into NADPH
NADPH then carries e- to other locations in cell
Can be used to create glucose

19. Light-Dependent Reactions
Use energy from light to produce O2 and converts ADP and NADP+ into ATP and NADPH
Photosystem II (PS II)
Chlorophyll a in PS II absorbs sunlight. This excites an e-.
This e- is captures by the primary e- acceptor.
An enzyme in the thylakoid splits water into 2 e-, 2 H+ ions, and an O atom. These e- replace the e- lost to the primary e- acceptor. Two O atoms combine to form O2.
e- are passed to the ETC.

20. Light-Dependent Reactions
ETC
High energy e- move through the ETC from PS II to PS I.
Energy from e- is used by molecules in ETC to transport H+ ions from stroma into inner thylakoid space.
Photosystem I (PS I)
Pigments in PS I use energy from light to reenergize e-.
NADP+ picks up an e- with an H+ to become NADPH.

21. Light-Dependent Reactions
Hydrogen Ion Movement
As e- are passed from chlorophyll at NADP+, more H+ ions are pumped across membrane.
Inside of the membrane fills with positively charged H+.
Difference in charges provides energy to make ATP.

22. Light-Dependent Reactions
ATP Formation
H+ ions can’t cross membrane directly.
ATP Synthase allows H+ to pass through it.
As H+ passes through ATP Synthase, the protein rotates.
As it rotates, ATP Synthase binds ADP and a phosphate group to produce ATP.

23. Light-Independent Reactions (aka Calvin Cycle)
Plants use energy that ATP and NADPH contain to build high energy compounds that can be stored for a long time.
The ATP and NADPH comes from light-dependent reactions.

24. Light-Independent Reactions (aka Calvin Cycle)
6 CO2 enter cycle from atmosphere. These 6 CO2 molecules combine with 6 5-carbon molecules. This results in carbon molecules.
The 12 3-carbon molecules are converted into high-energy forms. The energy comes from ATP and high-energy e- from NADPH.

25. Light-Independent Reactions (aka Calvin Cycle)
2 of the 12 3-carbon molecules are removed from cycle. These two molecules are used to produce sugars, lipids, amino acids, and other compounds.
The remaining 3-carbon molecules are converted back into 6 5-carbon molecules. They combine with 6 new CO2 molecules to begin a new cycle.
Uses 6 CO2 to produce a single 6-C sugar

26. Photosynthesis Light-Dependent Light-Independent
Includes
Light-Dependent
Light-Independent
Takes place in
uses
Takes place in
uses
Water
Energy from Sunlight
ATP
NADPH
Carbon dioxide
To produce
Thylakoid
Stroma
To produce
ATP
Oxygen
Of the
Chloroplast
High Energy Sugar
NADPH