Happy Early Thanksgiving!

Updates:

• Quiz 10 grades are updated, new average: 76%

• Last quiz average: 78%• Tools of the Light Trade assignment

counts as one quiz grade! Scores are up• Light Tools Findings grades will be

posted by the end of the night• I’m still missing just a few GD peer

evals…

Photosynthesis and Electron Transport

System

Let’s think…

• Electron transport…

• REDOX reactions?

• OIL RIG!

Why we’re here:

• Solve a question about the ‘invisible world’ through experimental design and execution

• Design the experiment given tools you have and processes you’re familiar with

• Derive the purpose and implementation of ‘controls’ for your experiment

Where we’re going

• Given: DCPIP takes electrons from Pq

In groups of two…

• What is DCPIP (Dichlorophenolindophenol)?

• Does it share any characteristics with other molecules we’ve seen this semester? What?

• What does it do?

• How can you tell what it’s doing/what it’s done?

Reduction of DCPIP:

Claims:

• DCPIP steals electrons– What effect do you predict this will have

on photosynthesis/oxidation of H2O by Photosystem II?

• An unknown herbicide blocks electron transport like a brick wall– What effects do you predict?

Verify these claims!

• How? Use the leaf disk assay we’ve been working with!

• What conditions?

• Key Question of the day: Where does the herbicide act? Before or after DCPIP?

Will Photosynthesis happen in DCPIP?

• How would you know?

• Add 4ml DCPIP + 20mL buffer

• ALSO, confirm an herbicide (Diuron) is a photosynthicide

• Add 0.75mL + 20mL buffer*

• Give your disks time to let the herbicide soak in

• *Ignore the change in volume adding these produce

Evaluations

• What did you learn? (Can be done individually while experiments progress)

• What did you think of the semester (requires lab instructor to be finished & gone; but you can come back)

Question of the day/week…

WHERE does the herbicide work?

X

X

Oh the thinks you can think!

• DCPIP taking -e will do what to O2 prod?

• How will -e taking affect DCPIP?

• How can you tell if drug acts here?

• Or here?

X

X

DCPIP taking e- will do what to O2 prod?

How will e- taking affect DCPIP?

How can you tell if drug acts here?

Or here?

Oh the thinks you can think!• Two hypotheses?

• What would your experiment look like?

• What would it TELL you if the DCPIP…

–Stays blue

–Turns clear

“Throw her into the pond!”• What tubes will you need?

• Work it out now

• Use the diagram