Enter your Sign-on user name and password.

Forgot password?
  • Follow us on:
Loading video...
Text Comments (8)

1 answer

Last reply by: Dr Carleen Eaton
Wed Nov 2, 2011 10:07 PM

Post by Anders Løvschal on October 30, 2011

This video is not working.

0 answers

Post by Tanul Gupta on January 25, 2012

Don't you need 12 NADPH for one glucose?

1 answer

Last reply by: Dr Carleen Eaton
Wed May 9, 2012 3:55 PM

Post by Gayatri Arumugam on May 5, 2012

Why is photolysis the spiting of water, shouldn't' be the plaiting of light? Photo means light and lysis means split. See time 21.45

1 answer

Last reply by: Dr Carleen Eaton
Sun Oct 21, 2012 10:31 PM

Post by jessica chopra on October 15, 2012

How many calvin benson cycles eventually make one glucose molecule?

0 answers

Post by Michael Amin on January 20 at 01:33:10 AM

Dr. Carleen,

Did you get your PHD 100 years ago because you look very young i cant believe it. The reason i say this is there is a problem in the very beginning of this lecture. "CO2 is used and oxygen is produced as a by product" This Statement would be incorrect the reason is.

The oxygen gas comes from water. A radioisotope of oxygen, oxygen-18, was used in a photosynthetic organism to trace the flow of the element. In one experiment, oxygen-18 was placed into water. In another experiment, oxygen-18 was placed into carbon dioxide. In the first experiment, the oxygen-18 ended up in the diatomic oxygen gas. In the second experiment, the oxygen-18 ended up in the saccharide and the water. This was done by a Doctor from Stanford University.

Photosynthesis

  • Through photosynthesis, light energy is converted into chemical energy.
  • Chloroplasts are the site of photosynthesis. They are surrounded by a double membrane and contain a fluid called stroma. Stacks of thylakoids form grana.
  • Photosystems in the thylakoid membranes consist of a reaction-center complex and light harvesting complexes.
  • During the light reactions, light energy is used to produce ATP. ATP production may occur either via noncyclic photophosphorylation or cyclic photophosphorylation.
  • The reactions in the Calvin cycle are the light independent reactions (dark reactions).
  • CO2 enters the Calvin cycle and through a series of reactions a precursor to glucose is produced. The ATP and NADPH produced during the light reactions are required for the Calvin cycle.
  • Under hot, dry conditions, O2 may be fixed by rubisco, instead of CO2, in a process called photorespiration. This process does not produce glucose or ATP.
  • C4 plants and CAM plants have adaptations to minimize the occurance of photorespiration.

Photosynthesis

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

AP Biology Intro