How carbon fixation does takes place in plants? pls help
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Answer:
Explanation:
What is Carbon Fixation?
What does it mean to fix something? It can mean to repair something that's broken, like fixing a car or a bike. But that's not the only meaning. You can fix something in place. If you take a thumb tack or push pin and put a piece of paper on a bulletin board it 'fixes' the piece of paper so that it won't fall off.
Carbon fixation is a process that involves fixing a carbon into place. Just like you take that piece of paper and tack it to the bulletin board so that it won't float around or end up on the floor, plants want to take carbon dioxide (CO2) out of the air and tack it to carbohydrates so it's not floating around all over the place. The process of taking inorganic carbon (usually CO2) and tacking it to an organic molecule (usually a carbohydrate) is known as carbon fixation.
Carbon fixation
The Calvin Cycle
So how exactly do plants go about taking the inorganic CO2 and tacking it onto a carbohydrate? This process of carbon fixation is actually the first step in the Calvin Cycle, also known as the Carbon Fixation Cycle or C3 cycle.
The first thing the cell needs is a molecule called ribulose-1,5-bisphosphate or RuBP for short.
The next thing the cell needs is a special enzyme. Enzymes are proteins that speed up chemical reactions. The enzyme the cell needs for carbon fixation is called ribulose-1,5-bisphosphate carboxylase. Ribulose-1,5-bisphosphate carboxylase is quite a mouthful so it's often shortened to RuBisCO.
RuBisCO is responsible for fixing the carbon, rather like you are responsible for tacking the paper onto the bulletin board. However, this enzyme works so slowly (in cellular terms) that plants need a whole lot of it in order to fix enough carbon for its needs. Because plants contain so much of this enzyme, it could be in the Guinness Book of World Records as Earth's Most Abundant Enzyme!
With RuBP, CO2 and RuBisCO, the plant cell is ready to fix carbon. RuBisCO takes the CO2 and adds it to the RuBP, creating a temporary intermediate molecule.
After the intermediate is formed, the whole molecule is separated into two 3-carbon molecules (hence, the name C3 cycle) called 3-phosphoglycerate (3PG). An equation for the reaction might look something like this: RuBP + CO2 = 2(3PG).
Carbon fixation forms 2 (3PG) molecules.
The 3PG is made into glyceraldehyde 3-phosphate (Ga3-P), which is used by the plant to produce sugar or starch, or to be cycled back to make RuBP, which again allows for carbon fixation.