Dictionary > C4 carbon fixation pathway

C4 carbon fixation pathway

Definition
noun
A metabolic pathway where CO2 is first added to phosphoenolpyruvate by the enzyme, PEP carboxylase, producing the four-carbon compound within mesophyll cells that is later transported to the bundle sheath cells where the CO2 is to be released for use in the Calvin cycle.
Supplement
Instead of the direct carbon fixation in the Calvin cycle like in C3 carbon fixation, the C4 pathway involves steps that first converts pyruvate to phosphoenolpyruvate (PEP) to bind with the CO2 forming a four-carbon compound (hence the name C4). As a result, the photorespiration pathway is bypassed, and the wasteful loss of CO2 common in C3 carbon fixation pathway is minimized.
Plants that first go through the C4 pathway are better adapted than plants that solely go through the C3 pathway under conditions of drought, high temperatures and low nitrogen or CO2 concentrations.
Word origin: from the intermediate organic compound, which contains four carbon atoms, hence the name C4.
Synonym: hatch slack kortshak pathway, Hatch-Slack pathway.

Compare: C3 carbon fixation pathway, Crassulacean acid metabolism.

See also: C4 plant.


You will also like...

Lentic community
Freshwater Communities & Lentic Waters

Lentic or still water communities can vary greatly in appearance -- from a small temporary puddle to a large lake. The s..

Gene Regulation in Eukaryotes
Gene Regulation in Eukaryotes

Learn about the general structure of a eukaryotic gene, the transcription factors, and post-transcriptional regulation....

genes controlling growth and development
Control of Growth & Development

Control of Growth & Development tutorials look at how the genetic makeup determines the biological processes on a da..

Human Nervous System
The Human Nervous System

The nervous system is essentially a biological information highway. This tutorial gives an overview of the nervous syste..

Schematic diagram of DNA replication
DNA Structure & DNA Replication

DNA is a double helix structure comprised of nucleotides. A nucleotide, in turn, is made up of phosphate molecule, deoxy..

Water Cycle
The Water Cycle

The water cycle (also referred to as the hydrological cycle) is a system of continuous transfer of water from the air, s..