Thymus vulgaris


Thymus vulgaris is autotrophic or “self-feeding” like most plants. Food and energy are produced by photosynthesis, a process in which plants use light energy from the sun and convert into chemical energy stored in organic molecules like glucose and molecules. Sunlight is absorbed by the chlorophyll in leaves. Water and CO2 are also needed for the plant to complete photosynthesis. Water comes from the roots and is pulled up through the xylem. CO2 comes from the stoma. The equation for photosynthesis is:
Light energy + 6 CO2 + 12 H2O yields C6H12O6 + 6 O2 + 6 H2O
Photosynthesis has two stages: the light reaction and the Calvin cycle. Both stages occur in the chloroplast. The chloroplast contains grana, stacks of the thylakoids. Each thylakoid in in the stack has photosystems that carries out photosynthesis.  The picture below shows a basic overview of photosynthesis.
                                   Photosynthesis  provided courtsey of                       
 The light stage occurs in the space outside of the grana or the stroma. Light is absorbed by the chloroplast or accessory proteins.  This light excites an electron in photosystem II, energizing the electron. This excited electron leaves a hole and replaced by an electron split from a water molecule. The energized electron is passed to an electron acceptor that transports it to photosystem I. The electron carrier takes the energized electron from photosystem I and transfers it NADP + making NADPH. ATP is also produced. H+ ions build up inside the thylakoid membrane throughout the light cycle and leave through ATP synthase which is used in other processes in the plant. Both ATP and NADPH are used the next step of photosynthesis.  
The Calvin cycle, also called the dark stage, is where glucose is made. Basically, there are three phases: carbon fixation, reduction, and regeneration. These three phases involve a series of chemical reaction that form G3P. Two G3P molecules make one glucose molecule; as a result, the Calvin cycle must happen twice to make one glucose molecule. Photosynthesis is a good thing. It takes the CO2 we breathe and changes it back to O2, which we need.

To read more about how thyme fits into the food chain go to the Interactions page or to read more about the life of a plant go to Reproduction.

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