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Classifying organisms according to their carbon source and energy supplies
Carbon fixation : The light independent reaction
Enzyme controlled reaction pathways
To find out the sequence of the reactions and the point at which X is added in, two approaches can be used:
Calvin and Benson 1946 to 1953
"Lollipop" vessel. A flat-sided, round flask containing the culture of algae
Labelling and tracing carbon using 14C
Add NaH14CO3 solution.
At timed intervals the algae are sampled and killed by dropping in hot methanol.
Two-way (2-dimensional) chromatography used to separate the compounds.
Identify radioactively labelled compounds by autoradiography.
The compound that became labelled first was Phosphoglyceric Acid (or Phosphoglycerate) PGA.
PGA is a 3 carbon sugar.
Therefore: Compound B + CO2 PGA
What is compound B?!!!
Searching for the compound that combines with carbon dioxide
Feed the algae NaH14CO3 for over 15 min so all the compounds involved in photosynthesis are labelled.
Then reduce the level of NaH14CO3 rapidly.
PGA levels should fall rapidly
The compound that fixes CO2 should rise sharply.
This compound was found to be Ribulose Bisphosphate (RBP)
RBP is a 5 carbon sugar
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