Welcome to our page !

This page serves as an entry point into our presentation covering processes of photosynthesis immediately upon absorption of light - the so called light reactions - taking place in photosynthetic membranes.

Special attention is given to the rate of these processes. Special time variables are introduced to let you appreciate the relative speed of partial processes. This is achieved by using log time and relative (to a calendar year) time variables. Here is how the time part of the presentation works:

An imaginary photosystem is given four light flashes in an interval of 10 ms. Time is followed on a special display. The relative time display shows the time of the year it would be if those 10 ms were streched to last a whole year! The logarithmic clock shows the value of -log10(t), it is only meaningful after the first flash, later the value does not change significantly. Real time is shown in appropriate units (down to femtoseconds). Remember, there are as many femtoseconds in a second as there are seconds in 31 million years ! In addition, text below images shows time that passed from the last flash.


Press the "Start the show" button below to see the light reactions of the photosynthetic process. To view events following later flashes, choose second, third or fourth flash in the pull-down menu. 

Show title bar at the top:    
Show text below images   :

A movie of the photosynthetic process is available (2.6MB).

Consider this movie experimental. If the sound annoys you, switch it off. At this moment this movie is hard to follow when running without interruption. However, many players allow you to step through the movie, so these may be used as a substitute for the web presentation.

This project was coordinated by Prof. Govindjee. The Web site was developed by Matej Lexa

The diagram of the thylakoid membrane used on these pages was adapted from
"The Photosynthetic Process" by J. Whitmarsh and Govindjee, Concepts in Photobiology: Photosynthesis and Photomorphogenesis, Edited by G.S.Singhal, G. Renger, S.K. Sopory, K.-D. Irrgang and Govindjee, Narosa Publishing Company, New Delhi, India/ Kluwer Academic, Dordrecht, The Netherlands.