PhotosynthesisPhotosynthesis

Is defined as…Is defined as… A process by which light energy is A process by which light energy is

converted into chemical energyconverted into chemical energy

Where does this take place?Where does this take place?

In the chloroplasts of plant cellsIn the chloroplasts of plant cells

The Basics:The Basics: Reactants and Products Reactants and Products

The main source of energy The main source of energy for all life is….for all life is….

The SUNThe SUN

Photosynthesis is the process of Photosynthesis is the process of converting sunlight into ATP then into converting sunlight into ATP then into organic molecules that store energy.organic molecules that store energy.

ATPATP

How is ATP like money?How is ATP like money? It is: Energy It is: Energy currencycurrency -- -- the only form of the only form of

energy living things can use (spend).energy living things can use (spend).

How does ATP release energy?How does ATP release energy?

By breaking the bond between the 2By breaking the bond between the 2ndnd and 3and 3rdrd phosphate and becoming ADP. phosphate and becoming ADP.

Autotrophs are…Autotrophs are…

Plants or other organisms that make their Plants or other organisms that make their own energy from the sun or inorganic own energy from the sun or inorganic compounds (they are producers)compounds (they are producers)

HeterotrophsHeterotrophs are consumers that… are consumers that…

Get energy from food by eating plants and Get energy from food by eating plants and animals that eat plantsanimals that eat plants

Where are the stroma and thylakoid Where are the stroma and thylakoid space relative to the thylakoid space relative to the thylakoid membrane?membrane?

The chloroplast contains thylakoids in a The chloroplast contains thylakoids in a fluid-filled space called the stroma.fluid-filled space called the stroma.

The thylakoid space is inside the The thylakoid space is inside the thylakoid and the membrane surrounds it.thylakoid and the membrane surrounds it.

Where is chlorophyll Where is chlorophyll located?located?

On the thylakoid membraneOn the thylakoid membrane

What is chlorophyll?What is chlorophyll?

A pigment that absorbs and reflects lightA pigment that absorbs and reflects light

What are the three What are the three products of photolysis?products of photolysis?

1 1 OxygenOxygen to the atmosphere to the atmosphere 2 2 H+ ionsH+ ions inside the thylakoid inside the thylakoid

membranemembrane 3 3 ElectronsElectrons to chlorophyll to replace to chlorophyll to replace

those lost to the ETCthose lost to the ETC

What frequencies of light are absorbed What frequencies of light are absorbed and reflected by chlorophyll?and reflected by chlorophyll?

Red and blue are absorbedRed and blue are absorbed

Green is reflectedGreen is reflected

What happens to chlorophyll when What happens to chlorophyll when it absorbs light energy?it absorbs light energy?

It loses excited electrons to the electron It loses excited electrons to the electron transport chain.transport chain.

How are these electrons replaced?How are these electrons replaced? Photolysis= light splitting water with an Photolysis= light splitting water with an

enzyme.enzyme.

Describe the ETC:Describe the ETC:electron transport chain.electron transport chain.

A series of protein molecules embedded A series of protein molecules embedded on the membrane where each one has a on the membrane where each one has a higher attraction for electrons than the higher attraction for electrons than the previous one.previous one.

What happens as the What happens as the energy is released in energy is released in each redox reaction?each redox reaction?

This energy is used to actively transport This energy is used to actively transport H+ ions into the thylakoid space against H+ ions into the thylakoid space against the gradient.the gradient.

This builds up a higher concentration of This builds up a higher concentration of H+ in the thylakoid space.H+ in the thylakoid space.

Are H+ freely permeable to the thylakoid Are H+ freely permeable to the thylakoid membrane? (can they cross easily?)membrane? (can they cross easily?)

No-- they are charged!No-- they are charged!

How do H+ ions diffuse out of the thylakoid How do H+ ions diffuse out of the thylakoid space into the stroma?space into the stroma?

Through a transport protein called…Through a transport protein called… ATP SynthetaseATP Synthetase

Is the flow of H+ ions through ATP Is the flow of H+ ions through ATP Synthase “energy requiring” or “energy Synthase “energy requiring” or “energy releasing”?releasing”?

Energy releasingEnergy releasing This energy is used to form ATPThis energy is used to form ATP

Is the formation of ATP Is the formation of ATP energy requiring or energy requiring or energy releasing?energy releasing?

Energy requiringEnergy requiring Energy is needed to create the bond Energy is needed to create the bond

between the 2between the 2ndnd and 3 and 3rdrd phosphate phosphate making ATP from ADP + Pmaking ATP from ADP + P

What serves as the final electron What serves as the final electron acceptor at the end of the electron acceptor at the end of the electron transport chain?transport chain?

NADP+NADP+

What happens to create NADPH?What happens to create NADPH? NADP+ combines with the final e- and NADP+ combines with the final e- and

H+ from the stroma to make NADPH.H+ from the stroma to make NADPH. NADPH is used in the next phase.NADPH is used in the next phase.

What three things are needed for the light What three things are needed for the light reactions? What three things are produced in reactions? What three things are produced in the light reactions?the light reactions?

Needed--Light, water, chlorophyllNeeded--Light, water, chlorophyll Produced--oxygen (to atmosphere), ATP, Produced--oxygen (to atmosphere), ATP,

and NADPH (to dark reactions)and NADPH (to dark reactions)

The dark reactions, AKA -- the light The dark reactions, AKA -- the light inindependent reactions, are also known dependent reactions, are also known as…as…

The Calvin CycleThe Calvin Cycle

What is carbon fixation and where does the What is carbon fixation and where does the carbon come from?carbon come from?

CO2 from the air is added to a 5 Carbon sugar CO2 from the air is added to a 5 Carbon sugar = this is “carbon fixation”= this is “carbon fixation”

Glucose is producedGlucose is produced

What is NADPH used for?What is NADPH used for?

It carries electrons and H+ ions to the It carries electrons and H+ ions to the Calvin Cycle.Calvin Cycle.

These are used to build glucose These are used to build glucose molecules.molecules.

What enzyme is key to this process?What enzyme is key to this process? RubiscoRubisco

Explain the results of the Explain the results of the Photosynthesis LabPhotosynthesis Lab

What light treatments had the highest What light treatments had the highest and the lowest rate of reaction?and the lowest rate of reaction?

What role did DPIP (blue stuff) play in the What role did DPIP (blue stuff) play in the photosynthesis reaction?photosynthesis reaction?

Now that you know all Now that you know all about photosynthesis..about photosynthesis..

Don’t forget to hug a tree!Don’t forget to hug a tree!

Without photosynthesis, we would not Without photosynthesis, we would not have air to breath or food to eat.have air to breath or food to eat.

THE END ?THE END ?