Photosynthesis, Carbon Fixation And
Virtually all life on Earth ultimately depends on the light-driven fixation of carbon dioxide (CO2) according to the following equation: 6CO2 + 6H2 O → C6 H12 O6 (glucose) + 6O2
Photosynthesis takes place in subcellular membrane-bound compartments called chloroplasts. As radiotracers such as carbon-14 became available to researchers following World War II (1939-45), one application was to define the biochemistry of photosynthetic CO2 fixation. Major class divisions in the plant kingdom are based on how CO2 is fixed.
C3 Photosynthesis.
Many important biological processes are sustained by cycles that continuously consume and renew one or more key intermediates while producing some other major product. Photosynthesis is sustained by the Calvin-Benson cycle.
The C3 photosynthetic mechanism is so named because the carbon atom of a molecule of CO2 taken up by an illuminated leaf is first detected in the three-carbon compound 3-phosphoglyceric acid (PGA). The vast majority of higher plants and algae are C3 species. PGA is formed when CO2 combines with a 5-carbon sugar, ribulose biphosphate (RuBP). The reaction is catalyzed by the enzyme RuBP carboxylase/oxygenase, an abundant protein in all green tissues. This multifunctional enzyme has come to be called rubisco.
This is a free page. This page contains 201 words. This
article contains 2,215 words (approx. 7 pages at 300
words per page).
Read the rest of this Article with our Photosynthesis, Carbon Fixation And Access Pass.