This page appears in the following eBook. Aa Aa Aa. Photosynthetic Cells. What Is Photosynthesis? Why Is it Important? Figure 2. Figure 3: Structure of a chloroplast. 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.
What Are the Steps of Photosynthesis? Figure 5: The light and dark reactions in the chloroplast. The chloroplast is involved in both stages of photosynthesis. Photosynthetic cells contain chlorophyll and other light-sensitive pigments that capture solar energy. In the presence of carbon dioxide, such cells are able to convert this solar energy into energy-rich organic molecules, such as glucose. These cells not only drive the global carbon cycle, but they also produce much of the oxygen present in atmosphere of the Earth.
Essentially, nonphotosynthetic cells use the products of photosynthesis to do the opposite of photosynthesis: break down glucose and release carbon dioxide. Cell Biology for Seminars, Unit 1. Topic rooms within Cell Biology Close. No topic rooms are there.
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For most plants, roots are responsible for absorbing water. The last requirement for photosynthesis is an important one because it provides the energy to make sugar. How does a plant take carbon dioxide and water molecules and make a food molecule?
The Sun! The energy from light causes a chemical reaction that breaks down the molecules of carbon dioxide and water and reorganizes them to make the sugar glucose and oxygen gas. After the sugar is produced, it is then broken down by the mitochondria into energy that can be used for growth and repair. The oxygen that is produced is released from the same tiny holes through which the carbon dioxide entered.
Even the oxygen that is released serves another purpose. Other organisms, such as animals, use oxygen to aid in their survival. The whole process of photosynthesis is a transfer of energy from the Sun to a plant. In each sugar molecule created, there is a little bit of the energy from the Sun, which the plant can either use or store for later.
Imagine a pea plant. If that pea plant is forming new pods, it requires a large amount of sugar energy to grow larger. This is similar to how you eat food to grow taller and stronger. All phycobiliproteins possess this exciting property of giving off visible light of a color different from the color of light that is shone on them.
APC takes up this light-red light and changes it to a deep red light for Chl. So, now we have the green light changed to red, which is the color of light that nature intended Chl to absorb. The entire process is a sort of a relay race, where each participant picks up where the previous one left off Figure 5. These phycobiliproteins are an important part of the tiny microscopic organisms called cyanobacteria, which carry out photosynthesis in much the same way as land plants do.
The only difference is that they use a different set of chemical molecules—cyanobacteria use phycobiliproteins while land plants use Chl. 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. Image Green Tree Leaves The plant leaves are green because that color is the part of sunlight reflected by a pigment in the leaves called chlorophyll. Photograph courtesy of Shutterstock.
Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. The process During photosynthesis, plants take in carbon dioxide CO 2 and water H 2 O from the air and soil. Chlorophyll Inside the plant cell are small organelles called chloroplasts, which store the energy of sunlight.
Light-dependent reactions vs. C3 and C4 photosynthesis Not all forms of photosynthesis are created equal, however. C3 photosynthesis. C4 photosynthesis. Calvin cycle. Part of the chloroplast where light-dependent reactions take place. Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. Media If a media asset is downloadable, a download button appears in the corner of the media viewer.
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