Calvin Cycle

1
Calvin Cycle

• Count the carbon atoms

2
CO2
2 C3 compound 3PG
Rubisco An enzyme
C6 Compound
Ribulose-bi-phosphate C5 compound
3
But hold on!

• Photosynthesis is a process resulting in the
  formation of glucose, a 6 carbon sugar
• Another product is oxygen gas that can be seen in
  algal mats as bubbles of air
• The glucose is moved from the chloroplast into
  the conducting tissue of the plant.
• Some glucose is moved to the root tissue for
  storage as starch.
• The oxygen that is produced in vascular plants
  leaves the plant through the same stomates
  through which carbon dioxide diffused into the
  leave cells

4
CO2
2 C3 compound 3PG
Rubisco An enzyme
C6 Compound
Ribulose-bi-phosphate C5 compound
C6H12O6 Glucose
5
So lets put some numbers with it
6 CO2
6 C6 Compound
12 C3 compound 3PG
Rubisco An enzyme
6 Ribulose-bi-phosphate C5 compound
6
6 CO2
12 C3 compound 3PG
6 C6 Compound
10 C3 compound G3P
6 Ribulose-bi-phosphate C5 compound
2 C3 compound G3P
Glucose A 6 carbon sugar
7
Lets add!
6 CO2
12 C3 compound 3PG
6 C6 Compound
10 C3 compound G3P
6 Ribulose-bi-phosphate C5 compound
2 C3 compound G3P
36 carbon atoms
Glucose A 6 carbon sugar
36 carbon atoms
8
Count the carbon atoms
6 CO2
12 C3 compound 3PG
6 C6 Compound
10 C3 compound G3P
6 Ribulose-bi-phosphate C5 compound
2 C3 compound G3P
Regeneration of 6 molecules of ribulose-bi-phospha
te
36 carbon atoms
Glucose A 6 carbon sugar
36 carbon atoms
9
Summary of counting the carbon atoms

• The Calvin cycle was discovered by Melvin Calvin,
  see p. 170 in your text
• This cyclical pattern is similar to that of the
  citric acid cycle in respiration
• A brief diagram can be seen at the bottom of p.
  171 in your text.
• None of the oxygen in the carbon dioxide molecule
  is used in the formation of oxygen gas
• All of the oxygen gas (O2) comes from the
  splitting of water in the light reaction. See
  page 162, experiment block at bottom of page.