C3 carbon fixation

C3 carbon fixation

c3 carbon fixation is a metabolic pathway for carbon fixation in photosynthesis. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into 3-phosphoglycerate through the following reaction:

:6 CO2 + 6 RuBP → 12 3-phosphoglycerate

This reaction occurs in all plants as the first step of the Calvin cycle. In c4 plants, carbon dioxide is drawn out of malate and into this reaction rather than directly from the air.

Plants that survive solely on c3 fixation (c3 plants) tend to thrive in areas where sunlight intensity is moderate, temperatures are moderate, carbon dioxide concentrations are around 200 ppm or higher, and ground water is plentiful. The c3 plants, originating during Mesozoic and Paleozoic era, predate the c4 plants and still represent approximately 95% of Earth's plant biomass. c3 plants lose 97% of the water taken up through their roots to transpiration.cite journal
author = Raven, J.A.
coauthors = Edwards, D.
year = 2001
title = Roots: evolutionary origins and biogeochemical significance
journal = Journal of Experimental Botany
volume = 52
issue = 90001
pages = 381–401
doi = 10.1093/jexbot/52.suppl_1.381
doi_brokendate = 2008-06-21
]

c3 plants must be in areas with high concentrations of carbon dioxide because RuBisCO often incorporates an oxygen molecule into the RuBP, instead of a carbon dioxide molecule. This breaks the RuBP into a three-carbon sugar that can remain in the Calvin cycle, and two molecules of glycolate which is oxidized into carbon dioxide, wasting the cell's energy. High concentration of carbon dioxide lowers the chance that RuBisCO incorporates an oxygen molecule. c4 and CAM plants have adaptations that allow them to survive in areas where the plant cannot take in a lot of carbon dioxide.

The isotopic signature of c3 plants shows higher degree of 13C depletion than the c4 plants.

ee also

* C4 carbon fixation
* CAM photosynthesis

References


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Carbon fixation — is a process found in autotrophs (organisms that produce their own food), usually driven by photosynthesis, whereby carbon dioxide is changed into organic materials. Carbon fixation can also be carried out by the process of calcification in… …   Wikipedia

  • C4 carbon fixation — is one of three biochemical mechanisms, along with C3 and CAM photosynthesis, used in carbon fixation. It is named for the 4 carbon molecule present in the first product of carbon fixation in these plants, in contrast to the 3 carbon molecule… …   Wikipedia

  • carbon fixation — noun any process, such as photosynthesis, whereby atmospheric carbon dioxide is converted into organic compounds …   Wiktionary

  • Carbon dioxide — Carbon dioxide …   Wikipedia

  • Fixation — may refer to the following:In science: *Fixation (psychology), the state in which an individual becomes obsessed with an attachment to another human, an animal, or an inanimate object *Fixation (visual) maintaining the gaze in a constant… …   Wikipedia

  • Carbon-13 — Infobox isotope alternate names = symbol =C mass number =13 mass = num neutrons =7 num protons =6 abundance =1.109% halflife = error halflife = background =#F99 text color = decay product = decay symbol = decay mass = decay mode1 = decay energy1 …   Wikipedia

  • fixation — ► NOUN 1) the action of fixating or the state of being fixated. 2) an obsessive interest in or feeling about someone or something. 3) the process by which some plants and micro organisms combine chemically with gaseous nitrogen or carbon dioxide… …   English terms dictionary

  • Carbon-14 — Infobox isotope background = #999999 isotope name = Carbon 14 num neutrons = 8 num protons = 6 isotope filename = alternate names = radiocarbon mass number=14 abundance = 1 part per trillion symbol=C decay product = 14N halflife=5,730 error… …   Wikipedia

  • carbon cycle — 1. Ecol. the circulation of carbon atoms in the biosphere as a result of photosynthetic conversion of carbon dioxide into complex organic compounds by plants, which are consumed by other organisms: the carbon returns to the atmosphere in the form …   Universalium

  • fixation — 1. The condition of being firmly attached or set. 2. In histology, the rapid killing of tissue elements and their preservation and hardening to retain as nearly as possible the same relations they had in the living body. SYN: fixing. 3. In… …   Medical dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”