Photosynthesis when does it happen

If you eat fruit, vegetables, grains or potatoes, thank a plant too. Plants and algae provide us with the oxygen we need to survive, as well as the carbohydrates we use for energy. They do it all through photosynthesis. Photosynthesis is the process of creating sugar and oxygen from carbon dioxide, water and sunlight. It happens through a long series of chemical reactions.

But it can be summarized like this: Carbon dioxide, water and light go in. Glucose, water and oxygen come out. Glucose is a simple sugar. Photosynthesis can be split into two processes. Both processes happen inside a chloroplast. This is a specialized structure, or organelle, in a plant cell.

The structure contains stacks of membranes called thylakoid membranes. Those membranes are filled with chlorophyll , a green pigment. This pigment absorbs light energy. Light travels as electromagnetic waves.

The wavelength — distance between waves — determines energy level. A Coleochaete orbicularis Charophyceae gametophyte; magnification x 75 photograph courtesy of L. B Chara Charophyceae gametophyte; magnification x 1. C Riccia liverwort gametophyte showing sporangia black embedded in the thallus; magnification x 5 photograph courtesy of A.

D Anthoceros hornwort gametophyte showing unbranched sporophytes; magnification x 2. E Mnium moss gametophyte showing unbranched sporophytes with terminal sporangia capsule ; magnification x 4. F Huperzia clubmoss sporophyte with leaves showing sessile yellow sporangia; magnification x 0. G Dicranopteris fern sporophyte showing leaves with circinate vernation; magnification x 0.

H Psilotum whisk fern sporophyte with reduced leaves and spherical synangia three fused sporangia ; magnification x 0. I Equisetum horsetail sporophyte with whorled branches, reduced leaves, and a terminal cone; magnification x 0. J Cycas seed plant sporophyte showing leaves and terminal cone with seeds; magnification x 0. Origin of land plants. New York: J. Wiley and Sons, All rights reserved. Part B: courtesy of M. Feist, University of Montpellier.

Coleochaete orbicularis. Both the gametophyte and the background are bright green. The gametophyte has an irregular circular shape and a scalloped edge. It is divided into many box-like segments cells , each with a visible, round nucleus inside. Panel b shows a Chara gametophyte. The organism has branching, tendril-like leaves reaching from a primary stalk. The green leaves are punctuated with small, round, yellow structures. A green liverwort gametophyte, In panel c, is protruding from the soil.

Its four primary stems each diverge into two halves and then branch again at their termini, so that each has a forked end. Panel d shows a hornwort gametophyte. Each green stem resembles a single blade of grass. Panel e shows moss gametophytes with sporophytes protruding from the ground. The gametophytes have small green leaves, and the sporophytes are thin, unbranched, brown stalks.

Each sporophyte has a fluorescent orange, oviform capsule called a sporangia perched on top of its stalk.

Panel f shows six clubmoss sporophytes emanating from the ground. Some stand vertically out of the soil, and some curve or have fallen horizontally. They have many stiff, protruding, spine-like, green leaves.

The sporangia are small yellow balls at the base of the leaves. Panel g shows fern sporophytes with many stems covered with small, elongated, symmetrical green leaves. Panel h shows a whisk fern sporophyte with long, straight, green stems beaded with yellow, round synangia along their lengths. In panel i, a horsetail sporophyte is shown. It has a single long stem, which is surrounded by a skirt of green leaves at its base and an elongated, yellow cone at the top.

Ultimately, light energy must be transferred to a pigment-protein complex that can convert it to chemical energy, in the form of electrons. In plants, for example, light energy is transferred to chlorophyll pigments. The conversion to chemical energy is accomplished when a chlorophyll pigment expels an electron, which can then move on to an appropriate recipient.

The pigments and proteins, which convert light energy to chemical energy and begin the process of electron transfer, are known as reaction centers. The reactions of plant photosynthesis are divided into those that require the presence of sunlight and those that do not.

Both types of reactions take place in chloroplasts : light-dependent reactions in the thylakoid and light-independent reactions in the stroma. Light-dependent reactions also called light reactions : When a photon of light hits the reaction center, a pigment molecule such as chlorophyll releases an electron.

The released electron manages to escape by traveling through an electron transport chain , which generates the energy needed to produce ATP adenosine triphosphate, a source of chemical energy for cells and NADPH. The "electron hole" in the original chlorophyll pigment is filled by taking an electron from water.

As a result, oxygen is released into the atmosphere. Light-independent reactions also called dark reactions and known as the Calvin cycle : Light reactions produce ATP and NADPH, which are the rich energy sources that drive dark reactions. Three chemical reaction steps make up the Calvin cycle: carbon fixation, reduction and regeneration.

These reactions use water and catalysts. These sugars are then used to make glucose or are recycled to initiate the Calvin cycle again. Photosynthetic organisms are a possible means to generate clean-burning fuels such as hydrogen or even methane. So, we now know that photosynthesis is the process by which plants produce their food, using Chl. We also know that the reduced amount of light available in the oceans decreases this photosynthetic process. Nature has evolved some helper chemical molecules known as phycobiliproteins, which are able to absorb the colors of light available in the oceans and turn this light into a color that Chl molecules can use.

These phycobiliproteins are found in tiny, invisible-to-the-naked-eye cyanobacteria, whose photosynthesis is responsible for providing food for the living organisms in the oceans and also for making the oxygen in our atmosphere that we breathe every second.

In the future, we hope to gain more understanding of the functions of phycobiliproteins and the roles that they may play for the benefit of mankind. Phycobiliproteins use this property to change the color of light they absorb so that the light can be used for photosynthesis.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Phycobilisome and phycobiliprotein structure. In: Bryant, D.

The Molecular Biology of Cyanobacteria. Dordrecht: Springer. Microalgal rainbow colours for nutraceutical and pharmaceutical applications. In: Bahadur, B. New Delhi: Springer. X ray crystallographic studies on C-phycocyanins from cyanobacteria from different habitats: marine and freshwater. Acta Crystallogr. F 61 9 —7.