LAB FOUR Photosynthesis

4A Plant Pigment Chromatography

4B Tracking the Light Reaction


•How is the light reaction affected by the presence or absence of light?

•How is it affected by the boiling of chloroplasts?


Isolated chloroplasts


boiled unboiled



boiled unboiled



light

dark



DPIP



boiled unboiled boiled unboiled



boiled unboiled boiled unboiled blank



DPIP replaces NADP+ in the light reactions of photosynthesis.




As DPIP is reduced, it turns from blue to colorless.





A spectrophotometer measures the absorption of blue light.

0%






10%






40%






80%

Cuvettes:

1.Blank (H2O only)

2.In the dark

3.Normal

4.Boiled chloroplasts

5.No chloroplasts



1 2 3 4 5Light Yes No Yes Yes Yes

Buffer 1 mL 1 mL 1 mL 1 mL 1 mL

H2O 4 mL 3 mL 3 mL 3 mL 3 mL + 3 drops

DPIP 1 mL 1 mL 1 mL 1 mL 1 mL

Chloro-plasts

3 drops 3 drops 3 drops 3 drops boiled

No

Cuvettes:

Keep all cuvettes on ice!

Adjust empty spectrophotometer to 0%

Adjust with blank cuvette to 100%

Add 3 drops chloroplast to your cuvette and immediately measure transmittance.

Measure again at 5, 10, and 15 minutes.


•Five teams will handle one cuvette each•Each team will take four measurements•Your turn lasts exactly one minute.



1 2 3 4 5Light Yes No Yes Yes Yes

Buffer 1 mL 1 mL 1 mL 1 mL 1 mL

H2O 4 mL 3 mL 3 mL 3 mL 3 mL + 3 drops

DPIP 1 mL 1 mL 1 mL 1 mL 1 mL

Chloro-plasts

3 drops 3 drops 3 drops 3 drops boiled

No

Cuvettes:

Keep all cuvettes on ice! .

Adjust empty spectrophotometer to 0%

Adjust with blank cuvette to 100%

Add 3 drops chloroplast to your cuvette and immediately measure transmittance.

Measure again at 5, 10, and 15 minutes.

.


LAB FOUR Photosynthesis

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Transcript of LAB FOUR Photosynthesis