Dictionary > C3 carbon fixation pathway

C3 carbon fixation pathway

Definition
noun
A metabolic pathway where CO2 is converted to 3-phosphogylycerate, the first stable intermediate organic compound containing three carbon atoms.
Supplement
The C3 carbon fixation pathway is in fact the initial phase of Calvin cycle. It starts with the enzyme rubisco catalyzing the carboxylation of Ribulose-1,5-bisphosphate by CO2 producing a highly unstable 6-carbon intermediate known as 3-keto-2-carboxyarabinitol 1,5-bisphosphate, which splits instantaneously into two molecules of the more stable 3-phosphogylycerate, an organic compound containing three carbon atoms (hence the name C3).
Plants that solely depend to C3 pathway for carbon fixation are faced with the negative effects of photorespiration, such as the wasteful loss of CO2. Photorespiration occurs under conditions of drought, high temperatures and low nitrogen or CO2 concentrations. These conditions cause the stomata to close in an attempt to prevent excessive water loss. The closure of stomata increases O2 levels, and the enzyme rubisco reacts with O2 instead of CO2, consequently losing CO2 instead of fixing CO2.
Word origin: from the intermediate compound, which contains three carbon atoms, hence the name C3.
Compare: C4 carbon fixation pathway, crassulacean acid metabolism.

See also: C3 plant.


You will also like...

sponge
Primitive Animals

Life, as we know it today, is presumed to have started in the sea and many of them were likely eukaryotic animal-like or..

Birth Control and Contraception
Birth Control and Contraception

Different pregnancy and birth control and contraception strategies are described. Read this tutorial to learn each of th..

Origins of Life on Earth
Origins of Life on Earth

Earth was created around 4.5 billion years ago and life began not long after. Primitive life likely possessed the elemen..

Selective Breeding
Selective Breeding

Gregor Mendel's studies into Monohybrid and Dihybrid crossing and Charles Darwin's study of evolution and natural select..

Ecosystem Succession
Ecosystem Succession

If the balance of nature is left untouched, landscapes can change dramatically over time. A previous ecosystem is supers..

Golgi apparatus (3-D illustration)
Role of Golgi Apparatus & Endoplasmic Reticulum in Protein Synthesis

The endoplasmic reticulum and Golgi apparatus are the organelles involved in the translation step of protein synthesis a..

Related Articles...

No related articles found

See all Related Topics