What makes glucose from sunlight

One represents the production of biomass in the trees, and the other represents the production of atmospheric carbon dioxide CO 2. Arrows emanating from a tree's roots point to two molecular structures: inorganic carbon and organic carbon, which may decompose into inorganic carbon. Inorganic carbon and organic carbon are stored in the soil. This CO2 can return to the atmosphere or enter rivers; alternatively, it can react with soil minerals to form inorganic dissolved carbonates that remain stored in soils or are exported to rivers.

B The transformations of organic to inorganic carbon through decomposition and photosynthesis continue in rivers; here, CO2 will re-exchange with the atmosphere degassing or be converted to dissolved carbonates. These carbonates do not exchange with the atmosphere and are mainly exported to the coastal ocean. Organic carbon is also exported to the ocean or stored in flood plains. C In the coastal ocean, photosynthesis, decomposition, and re-exchanging of CO2 with the atmosphere still continue.

Solid organic carbon e. Dissolved inorganic and organic carbon are also exported to the open ocean, and possibly deep-ocean waters, where they are stored for many centuries. Indeed, the fossil fuels we use to power our world today are the ancient remains of once-living organisms, and they provide a dramatic example of this cycle at work. The carbon cycle would not be possible without photosynthesis, because this process accounts for the "building" portion of the cycle Figure 2.

However, photosynthesis doesn't just drive the carbon cycle — it also creates the oxygen necessary for respiring organisms. Interestingly, although green plants contribute much of the oxygen in the air we breathe, phytoplankton and cyanobacteria in the world's oceans are thought to produce between one-third and one-half of atmospheric oxygen on Earth.

Photosynthetic cells contain special pigments that absorb light energy. Different pigments respond to different wavelengths of visible light. Chlorophyll , the primary pigment used in photosynthesis, reflects green light and absorbs red and blue light most strongly. In plants, photosynthesis takes place in chloroplasts, which contain the chlorophyll. Chloroplasts are surrounded by a double membrane and contain a third inner membrane, called the thylakoid membrane , that forms long folds within the organelle.

In electron micrographs, thylakoid membranes look like stacks of coins, although the compartments they form are connected like a maze of chambers. The green pigment chlorophyll is located within the thylakoid membrane, and the space between the thylakoid and the chloroplast membranes is called the stroma Figure 3, Figure 4. Chlorophyll A is the major pigment used in photosynthesis, but there are several types of chlorophyll and numerous other pigments that respond to light, including red, brown, and blue pigments.

These other pigments may help channel light energy to chlorophyll A or protect the cell from photo-damage. For example, the photosynthetic protists called dinoflagellates, which are responsible for the "red tides" that often prompt warnings against eating shellfish, contain a variety of light-sensitive pigments, including both chlorophyll and the red pigments responsible for their dramatic coloration.

Figure 4: Diagram of a chloroplast inside a cell, showing thylakoid stacks Shown here is a chloroplast inside a cell, with the outer membrane OE and inner membrane IE labeled.

Other features of the cell include the nucleus N , mitochondrion M , and plasma membrane PM. At right and below are microscopic images of thylakoid stacks called grana. Note the relationship between the granal and stromal membranes. Protein import into chloroplasts. Nature Reviews Molecular Cell Biology 5, doi Figure Detail. Photosynthesis consists of both light-dependent reactions and light-independent reactions. In plants, the so-called "light" reactions occur within the chloroplast thylakoids, where the aforementioned chlorophyll pigments reside.

When light energy reaches the pigment molecules, it energizes the electrons within them, and these electrons are shunted to an electron transport chain in the thylakoid membrane. Meanwhile, each chlorophyll molecule replaces its lost electron with an electron from water; this process essentially splits water molecules to produce oxygen Figure 5.

Figure 5: The light and dark reactions in the chloroplast The chloroplast is involved in both stages of photosynthesis. The light reactions take place in the thylakoid. There, water H 2 O is oxidized, and oxygen O 2 is released.

The dark reactions then occur outside the thylakoid. The products of this reaction are sugar molecules and various other organic molecules necessary for cell function and metabolism. Note that the dark reaction takes place in the stroma the aqueous fluid surrounding the stacks of thylakoids and in the cytoplasm. The thylakoids, intake of water H 2 O , and release of oxygen O 2 occur on the yellow side of the cell to indicate that these are involved in the light reactions. The carbon fixation reactions, which involve the intake of carbon dioxide CO 2 , NADPH, and ATP, and the production of sugars, fatty acids, and amino acids, occur on the blue side of the cell to indicate that these are dark reactions.

An arrow shows the movement of a water molecule from the outside to the thylakoid stack on the inside of the chloroplast. Another arrow shows light energy from the sun entering the chloroplast and reaching the thylakoid stack.

An arrow shows the release of an oxygen molecule O 2 from the thylakoid stack to the outside of the chloroplast. Once the light reactions have occurred, the light-independent or "dark" reactions take place in the chloroplast stroma.

During this process, also known as carbon fixation, energy from the ATP and NADPH molecules generated by the light reactions drives a chemical pathway that uses the carbon in carbon dioxide from the atmosphere to build a three-carbon sugar called glyceraldehydephosphate G3P. Cells then use G3P to build a wide variety of other sugars such as glucose and organic molecules.

Many of these interconversions occur outside the chloroplast, following the transport of G3P from the stroma. The glucose molecule goes on to bigger things. Plants also can store the energy packed in a glucose molecule within larger starch molecules. All of these molecules are carbohydrates — chemicals containing carbon, oxygen and hydrogen. CarbOHydrate makes it easy to remember. The plant uses the bonds in these chemicals to store energy.

But we use the these chemicals too. Carbohydrates are an important part of the foods we eat, particularly grains, potatoes, fruits and vegetables. By Bethany Brookshire October 28, at am. Chloroplasts are found in plant cells. This is where photosynthesis takes place. The chlorophyll molecules that take in energy from sunlight are located in the stacks called thylakoid membranes.

The Calvin cycle has four major steps: carbon fixation : Here, the plant brings in CO 2 and attaches it to another carbon molecule, using rubisco.

This is an enzyme , or chemical that makes reactions move faster. This step is so important that rubisco is the most common protein in a chloroplast — and on Earth. Rubisco attaches the carbon in CO 2 to a five-carbon molecule called ribulose 1,5-bisphosphate or RuBP.

This creates a six-carbon molecule, which immediately splits into two chemicals, each with three carbons. The sugar molecules are called G3P. This RuBP pairs up with rubisco again. They are now ready to start the Calvin cycle again when the next molecule of CO 2 arrives. Animals What biologists call a species is becoming more than just a name By Jack J.

Lee October 14, In the second step of photosynthesis, carbon dioxide from the air enters the leaves through very small openings. Using the previously stored chemical energy, the chloroplasts convert carbon dioxide into glucose [ 1 ]. Fructose is also produced during this step. Glucose is then combined with fructose to create sucrose.

People have always found substances to sweeten food. But, in cool climates, sugar was luxury product for many years. In , the German chemist Andreas Sigismund Marggraf discovered that beets produce the same sugar as sugar cane. His student developed a technical process to extract the sugar from beets.

The first sugar factory became operational in Soon, many sugar factories were built all over Europe. The sugar beet plant called Beta vulgaris in Latin has bright green leaves in a rosette pattern and a cone-shaped, white, fleshy root Figure 2.

Cultivation of crops may look simple, but this is not true if you want to grow crops large enough to feed many people. Let us have a look at how sugar beets are cultivated Figure 3.

Our journey starts with the sugar beet seed. One sugar beet seed naturally develops into many plants. Until the s, the unnecessary plants needed to be removed by hand so that the beets were not too crowded, which was strenuous and time-consuming work. Then, plant breeders had a breakthrough and introduced seeds that produce only a single seedling. Seed breeders that make sugar beet seeds coat the seeds with pesticides that protect seedlings against diseases and pests.

The coated sugar beet seed is called the pill , and the pills often have different colors depending on the breeder Figure 3A. When the seeds germinate, small roots and two seed leaves, called cotyledons , emerge Figure 3B. From this point on, the young sugar beet plant must be protected from weeds, because weeds compete for sunlight and soil nutrients. Farmers can control the weeds with a hoe or can use herbicides, which are chemicals that kill the weeds.

Beets do not only have to fight against competing weeds. They are also attacked by insects. Beet-attacking insects can be separated into two groups: those that directly damage the plant and those that transmit viral diseases.

The green peach aphid Myzus persicae , for example, can transmit a virus causing a yellowing of the sugar beet leaves, which inhibits photosynthesis and reduces sugar production.

Sucrose produced in the leaves is stored in the beet. The sunnier the summer, the more sugar can be produced via photosynthesis. During this time, the leaves must be protected against fungal diseases, because only healthy leaves can perform photosynthesis. The most widespread and destructive disease of sugar beet leaves is caused by a fungus with the Latin name Cercospora beticola. At first, only small circular dark spots with a reddish border are visible, but the fungus produces a toxic substance that destroys the leaf tissue and ends up killing large areas or even whole leaves.