PHOTOSYNTHESIS

Where do each of the molecules come in/go out of a plant?

What happens to the atoms in this equation?

water Cell that regulate the opening that allow gases to pass Columnar cells packed tightly together Perform lots of photosynthesis Waxy covering of leaf Loose layer of cells. Performs photosynthesis. Spaces between allow movement of gasses Allows for transportation of materials water

CO2 enters the leaf through the stomata

Overview of Light Reactions Light strikes chlorophyll a excites electrons to a higher energy state. the energy is converted by way of electron transport to NADPH and ATP Water is split in the process oxygen released as a by-product The ATP and NADPH are used to make C-C bonds in the Calvin Cycle

Light energy is being converted into chemical energy

Characteristics of light

What composes a photosystem? Antenna pigments is a few hundred chlorophyll a, chlorophyll b and carotenoid molecules Reaction center contains reaction center chlorophyll a this is the only chlorophyll that can initiate photosynthesis Primary electron acceptor

Review light reactions

Cyclic vs. noncyclic electron flow Noncyclic is what we’ve discussed so far Cyclic uses only photosystem I -the excited electron is accepted by primary electron acceptor -is then passed to the ETC between the two photosystems -ATP is produced -NO NADPH is produced

Cyclic electron flow

Light Independent Reactions AKA Calvin-Benson Cycle Occur in the stroma Use the products of the light reactions Incorporates the Carbon from CO2 into sugar molecules

CALVIN CYCLE -is cyclic in that the starting material (RuBP a 5 carbon sugar) is regenerated 3 phases 1) Carbon fixation -CO2 is incorporated into an organic molecule -3 molecules of CO2 combines with 3 RuBP -resulting 6 C molecules split to form 6 3-C molecules -catalyzed by enzyme rubisco

2) Reduction ATP is used to phosphorylate the 3-C molecule which is then reduced by NADPH -a 3-C sugar is produced -this can be converted to glucose by the plant 3) Regeneration of CO2 acceptor (RuBP) The skeleton of the 5-C molecule is rearranged -ATP used -resulting RuBP begins a new cycle

calvin

This is the C3 pathway A problem occurs when the stomata must be closed to conserve water loss -too little CO2 available -build up of O2 leads to photorespiration -rubisco adds O2 to Calvin cycle instead of CO2 -no ATP or NADPH produced -no food produced -is wasteful

This is the C3 pathway A problem occurs when the stomata must be closed to conserve water loss -too little CO2 available -build up of O2 -leads to photorespiration Photorespiration -rubisco adds O2 to Calvin cycle instead of CO2 -no ATP or NADPH produced -no food produced -is wasteful

C4 Plants CO2 binds with a 4-C compound that ends up being transferred to a bundle sheath cell -here it is released and enters Calvin cycle C3 plant C4 plant

CAM plants -also have adaptations to arid conditions -found in succulents (pineapple, cacti, others) -open stomata at night (opposite of other plants) -incorporate the CO2 into a variety of organic acids and store in vacuoles -during day CO2 is released from organic acids and enters the Calvin cycle

Comparison of chemiosmosis in chloroplasts and mitochondria SIMILARITIES An ETC in a membrane transports protons across a membrane ATP synthase in membrane couples diffusion of protons with phosphorylation of ADP ATP synthase and electron carriers (cytochromes) are very similar in both

ETC SPACIAL ORGANIZATION DIFFERENCES -mito transfer chemical E from food to ATP -electrons are extracted from oxidation of food molecules -chloroplasts transform light E into chemical E -uses light E to drive electrons to top of transport chain SPACIAL ORGANIZATION -mito pump protons from matrix out to the intermembrane space (which is a reservoir for protons) -chloro. Thylakoid membrane pumps protons from stroma into thylakoid compartment (serve as a proton reservoir)

Temp Time Germinating peas Non Germinating peas average Room temp 5 .110 .07 .04 .073 -.17 .01 -.053 10 .204 .17 -.02 .118 -.19 -.063 15 .225 .24 -.10 .12 -.2 -.067 20 .195 .325 -.26 .087 -.205 -.075 10° C .00 .02 .15 .057 -.12 -.05 .20 .25 . -.22 .29 -.47

Lab Notebook: Hypothesis (which peas will have the greatest respiration rate) Data: individual and class data Analysis: Graph class average results (4 best fit lines) Include a key 2) Questions 2, 5, 6, 7, 9 Thoroughly answer these questions and use evidence from the lab to support your answer when possible