[Ecoed] photosynthesis lab

[David Puthoff]

Hi All,

I am teaching an introductory biology class for
college freshmen and I was looking for some help with
a photosynthesis lab experiment. Basically, we will be
using DCPIP as an electron acceptor. I am a little
confused as to how to prep the chloroplasts in order
to carry out the experiment.
Basically, spinach leaves are homogenized in sodium
phosphate buffer (0.05 M pH 7.6) with 0.35 M sucrose.
After centrifugation to pellet the chloroplast they
are resuspended in the sucrose phosphate buffer. 

The question I have is if I should always be using the
sucrose phosphate buffer or switch to just phosphate
buffer during later times in the protocol. 

For example, we then dilute the chloroplasts about
5-fold to conduct the actual experiment. Should this
dilution be in the sucrose phosphate buffer or just
phosphate buffer. I am worried about chloroplast
lysis.
I hope I have been clear. Any information would be
greatly appreciated.

David Puthoff


      ____________________________________________________________________________________
Luggage? GPS? Comic books? 
Check out fitting gifts for grads at Yahoo! Search
http://search.yahoo.com/search?fr=oni_on_mail&p=graduation+gifts&cs=bz