Nutrition

All organisms must have some system of obtaining energy to perform their functions, whatever they may be. The way of obtaining this energy is called nutrition. Among all organisms, nutrition  is a incredibly varied process.

Organisms that make their own food are given the title of autotrophic. Let's dissect this using Latin, auto- means self and -trophic means feeding, which accurately explains how Convallaria majalis, and most other plants for that matter, get their energy. Autotrophic plants are also considered primary producers, since they use inorganic materials to create organic ones.

 The process by which these organic molecules are created in autotrophs is called photosynthesis. Your biggest questions about photosynthesis are about to be answered, so get ready! Photosynthesis can be summarized in a chemical equation; an equation that stands for a complex series of reactions. The photosynthesis equation is below.

  
        Zoofari, Wikimedia Commons, 2010.

WHAT?
As seen above, there are a few things that must be present for photosynthesis to occur. First off is carbon dioxide, which will help give us the organic component of the organic compound (sugar). This carbon dioxide comes from the atmosphere. Water will be the electron donor in this entire process, which I will outline in further detail down this page. It is important to note that this water usually comes from the roots, where it was absorbed from the soil, with the help of some special interactions found in the roots. The electron donated by water will be excited by light, usually sunlight. With these three things present, the photosynthetic organism will go through two separate processes to create sugar, the organic compound necessary to harvest energy. Oxygen is created as a waste product of the plant, it is the result of the split water molecule.

WHY?
It is important to remember the place of photosynthesis in the large scheme of things. The purpose of the entire process is to create energy to power the cells of the plant. To the left is a diagram of the general overview of photosynthesis. Although it seems complex, once we break the process down, it will be much more understandable, I promise! First off note that photosynthesis is broken down into two major steps: the Light Reactions and the Calvin Cycle. Both of these cycles are incredibly important in the creation of sugars for the plant, and they are discussed in greater detail below. It is important to realize that through out the process, ATP and NADPH are regenerated. Both of these molecules are able to carry a lot of energy in their many bonds, and that is what makes them so useful in this process. Energy must be invested to create the bonds, but energy is released when the bonds are broken.

    Daniel Mayer, Wikimedia Commons, 2008.

WHERE?
The entire process about to be outlined is happening in the chloroplast of a leaf cell within Convallaria majalis in a matter of seconds. The chloroplast is a specialized organelle within in the plant.  Other plant organelles serve as excellent adaptations as well. The chloroplast gives the plant its green color and is usually the easiest structure to identify when looking at plant cells under a microscope. Notice the diagram on the right, it labels the parts of the chloroplast, but we are most concerned with the
 thylakoid and the stroma. The thylakoid        It'sJustMe, Wikimedia Commons, 2005.
is a series of folded membranes, and some of photosynthesis actually happens in this membrane. The thylakoid membrane has special pigments, or molecules that reflect certain frequencies of light, embedded in it, called chlorophyll. The stroma is the fluid that fills the chloroplast. The other half of photosynthesis will actually happen within this fluid. With these things located and defined, let's break this process down even more.

Warning: If these explanations don't make much sense to you, don't stop reading! Check out the video links for a visual representation.

HOW?
Photosynthesis is broken down into two different steps. Each of the steps serves a different purpose within the entire photosynthetic cycle.

 The Light Reactions
The first part of photosynthesis requires capturing the energy of the light, hence the name the Light Reactions. This part of photosynthesis will be occurring within the thylakoid membrane. The light reactions revolve around changing light energy into chemical energy, or energy stored in chemical bonds. These chemical bonds must have energy invested and stored into them in the Light Reactions. This energy will later be used in the Calvin Cycle. NADP⁺ and ADP are the means by which this chemical energy will travel.
The Light Reactions begin with water being split into O₂, which will eventually be released via special adaptations within the leaf, H⁺ and an electron. This electron will enter an excited state with the help of light and the chlorophyll molecules. The electron will move through two different groupings of chlorophyll called photosystems. After this, the electron will eventually bond to NADP⁺ and create NADPH, an energy rich molecule that will be used in the Calvin Cycle.
Now the H+ that was split from the water, will be used to help make the ADP into ATP.

The Calvin Cycle
The Calvin Cycle, sometimes called the Dark Reactions follows the Light Reactions in the plant. This series of reactions will occur within the stroma, or the fluid within the chloroplast. The Calvin Cycle will utilize the NADPH and ATP made in the light reactions to power through a series of reactions to turn atmospheric and inorganic CO₂ into C₆H₁₂O₆, or sucrose, a useable plant sugar. An enzyme, or a specialized group of proteins that help a reaction occur, is necessary to start of the cycle. RuBisCo is this enzyme. RuBisCo will take the CO₂ and take it through a series of reactions in order to turn it into the useable form of energy. ATP and NADPH will be used in these enzymes to provide energy. When the energy is harvested from the bonds in these molecules, they will return to their less energetic forms, ADP and NADP⁺. Both will return to the thylakoid membrane in order to regain these bonds, so they can be recycled for continual reuse. The most important result of the Calvin Cycle is the creation of sucrose, C₆H₁₂O₆, the most useable, transportable and arguably important compound found within plants.

So there you have it, you have just created plant energy! Take your time exploring the complexities of photosynthesis with this interactive and detailed model of what goes on in each step. This video goes in depth into the reactions that take place, but is an excellent visual representation of what is happening during photosynthesis. To find out how these sugars, as well as water are transported within the plant, check out water and sugar movement on the adaptations page.

The plant uses this sugar for energy and growth. Continue on to Convallaria majalis life cycle page to learn how this plant uses this energy.