Light reaction Dark reaction Photosynthesis Light reaction Dark reaction

Key components of the Light Reaction 2 photosystems 2 electron transport chains ATP synthase Embedded in the _________ Which organelle? _________

The photosystems, 1 & 2 They are an array of _________molecules What do these molecules do? Hint: They absorb light energy And, the absorbed energy excites its electrons to a higher energy level

Photosystem 1 Energized electrons are passed down an ____________ What do these electrons end up doing? Hint: They are added to NADP+ to form NADPH

Photosystem 2 Meanwhile energized electrons are passed down another ____________ What do these electrons end up doing? Hint: H+ Their energy is used to pump H+ From the __________ into the ___________ compartment

What does pumping H+ ions cause? Hint: What does pumping H+ ions cause? Concentration gradient Where do these electrons go? And, why? Hint: To photosystem 1 To replenish its lost electrons How does this photosystem replenish its electrons? Hint: By splitting water

So, photosystem 1 is thought of as the: Hint: The NADPH producing photosystem And, photosystem 2 is thought of as the: Hint: The water splitting photosystem

What is the ‘tally’ of energy production so far? Hint: Hint: What about ATP? Remember the hydrogen ions? The buildup of __________ inside the ___________ compartment stores __________ energy.

The potential energy is harvested by what enzyme? Hint: ATP synthase And, how is ATP made? 1 2 3 4 5 6 3 2 5 4 6 1

Next, the ‘sugar-producing’ Calvin cycle The final look at energy production from the light reaction: NADPH ATP No sugar produced in the light reactions!

The Calvin cycle What energy does the Calvin cycle use? Hint: NADPH ATP What else does the Calvin cycle need to get started? CO2

A quick rundown of the Calvin cycle tells us that: Carbon is used from _________ Energy is used from _________ High energy electrons are used from ______ The cycle itself produces an energy-rich molecule called _________ The plant cell uses ______ as raw material to make ________

Called a cycle because: Regenerates the starting material with each turn of the cycle What is the cycle? A complex series of chemical reactions Where does it occur? In the stroma of the chloroplast

What is the carbon bound to? The cycle begins with: Input of CO2 (how many?) What is the carbon bound to? RuBP molecules (how many?) But, what happens to RuBP? Its broken up into 3-PGA RuBP: ribulose bisphosphate, a 5 carbon sugar 3-PGA: 3-phosphoglyceric acid, a 3 carbon compound

What happens to ATP, NADPH? What is the next step? G3P? 3 PGA? Energy is required To convert __________ to product __________ What happens to ATP, NADPH? G3P: glyceraldehyde 3-phosphate, a 3 carbon sugar

Half way around the cycle… CO2 3 PGA RuBP Does this diagram represent one or more turns of the cycle? G3P What is the name of this molecule?

What happens with one full turn of the cycle? G3P 3 PGA CO2 Starting material _______ is regenerated How many molecules of direct product are produced at this point?

One complete cycle … How many cycles to make one glucose?

Depending on the needs of the plant, what are some facts about G3P? Some G3Ps are used to build glucose Glucose can combine into starch Or cellulose

Still other G3P’s form sucrose Some sugar is broken down by cellular respiration Uses oxygen in the plant’s own mitochondria Generates ATPs that powers other work of the plant Excess oxygen diffuses out of the leaf through the pores, while more CO2 enters

Learning check The Calvin cycle must turn ______ times for the plant to be able to produce a single molecule of glucose. What is the function of NADPH in the Calvin cycle? The Calvin cycle takes place in the ______.