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By the end of this section, you will be able to:
  • Describe the Calvin cycle
  • Define carbon fixation
  • Explain how photosynthesis works in the energy cycle of all living organisms

Intro into carbon fixation

The general principle of carbon fixation is that some cells under certain conditions can take inorganic carbon, CO 2 (also referred to as mineralized carbon) and reduce it to a usable cellular form. Most of us are aware that green plants can take up CO 2 and produce O 2 in a process known as photosynthesis. We have already discussed photophosphorylation, the ability of a cell to convert light energy to chemical energy in the form of a high energy electron that then enters the electron transport chain to produce ATP and NADPH, see module as described in Module 6.3. In photosynthesis, the plant cells use the ATP and NADPH formed during photophosphorylation, the light reactions, to reduce CO 2 to sugar, (as we will see, specifically G3P) in what is called the dark reactions. While we all familiar with this process in green plants, I want to point out that this process had its origins in the bacterial world. ATP and NADPH can be made during anoxygenic photophosphorylation and CO 2 into reduced sugars for the cell. In this module we will go over the general reactions of the Calvin Cycle, a reductive pathway that incorporates CO 2 into cellular material. In many ways it is the reverse of the oxidative pentose phosphate pathway. One exercise to keep in mind is to look for the similarities between these two pathways.

A note from the instructor

As with the modules on glycolysis, the TCA cycle, and the Pentose Phosphate Pathway, there is a lot of material in this module. AS with these other modules, I do not expect you to memorize specific names of compounds or enzymes. However, as in those other modules I will give include the names for completeness. For exams I will always provide you with the pathways we discuss in class and in the BioStax Biology text modules. What you need to be able to do is understand the under lying principles for each reaction. We will go over in lecture problems that will be similar to those I will ask of you on exams. Do not be overwhelmed with specific enzyme names and specific structures. What you should know are the general types of enzymes used and the types of structures found. If you have any questions please ask.

Fixing carbon into biological molecules

After the energy from the sun is converted into chemical energy and temporarily stored in ATP and NADPH molecules, the cell has the fuel needed to build carbohydrate molecules for long-term energy storage. The products of the light-dependent reactions, ATP and NADPH, have lifespans in the range of millionths of seconds, whereas the products of the light-independent reactions (carbohydrates and other forms of reduced carbon) can survive for hundreds of millions of years. The carbohydrate molecules made will have a backbone of carbon atoms. Where does the carbon come from? It comes from carbon dioxide, the gas that is a waste product of respiration in microbes, fungi, plants, and animals.

Questions & Answers

Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
what does post-translational control refer to?
Teresa Reply
Bioremediation includes
Rachel Reply

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Source:  OpenStax, Ucd bis2a intro to biology v1.2. OpenStax CNX. Sep 22, 2015 Download for free at https://legacy.cnx.org/content/col11890/1.1
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