Temperature and molecules effect on coffee plantation
Photosynthesis and Cellular Respiration on the farm
All life processes are supported by the simple sugar glucose. Glucose is both the primary source of energy for these processes and an important building block for many other compounds. Plants capture light energy through their leaves and use it to convert carbon dioxide and water into glucose. The process is called ‘photosynthesis’. Photosynthesis is the source of all of the organic compounds and most of the energy used to sustain life on Earth. Oxygen is a by-product of photosynthesis. Photosynthesis produces most of the oxygen in our atmosphere.
Plant leaves contain pigments called chlorophyll that absorb red and blue wavelengths of light and reflect green light, which is why leaves appear green to our eyes. When a chlorophyll molecule absorbs a single photon of light, it releases a single electron that is used to drive the reactions that create glucose.
Chlorophyll is contained in organelles (Structures within cells e.g. chloroplasts) known as chloroplasts. Inside the chloroplasts, the chlorophyll is stored (A milk pattern which involves a series of lines applied to the surface of a drink, using the pushing technique; this design harnesses the effect of the eddies to stretch each line around the edges of the cup. This pattern is an extension of the tulip design.) in the membrane of little green pancake-like stacks known as thylakoids(A thylakoid is a membrane-bound compartment inside chloroplasts and cyanobacteria). The light-dependent reactions take place at the thylakoid membrane that surrounds these little pancakes. It is also here at the that the oxygen we breathe is created.
- What Other Ingredients Do Plants Need to Produce Glucose?
Plants need carbon dioxide and water to produce glucose, which is made of carbon, hydrogen, and oxygen. 6 CO2 + 6 H2O → C6H12O6 + 6 O2. (→ = Light energy plus chlorophyll).
A plant’s roots take up water from the soil. Xylem, a woody tissue containing bundles of capillaries, transports water and minerals throughout the plant. The carbon dioxide that is needed for photosynthesis comes directly from the atmosphere. It is taken into the leaves of plants through small pores known as stomata(The pores in a leaf that open and close when the plant requires to allow gases and moisture to diffuse in and out of the leaf when needed). The stomata allow the CO₂ to diffuse into the leaf.
In this image, you can see the leaves outer layer called the epidermis, peeled away to reveal the plant cells inside the leaf which contain the chloroplasts
Light-dependent Reactions
The first step in photosynthesis is the light-dependent reaction. In this step, chlorophyll molecules absorb photons and use this energy to release an energized electron. The electron is passed to a chain of molecules and enzymes that use it to create two energy-carrying molecules, ATP and NADPH. To replace the lost electrons, the chlorophyll splits water molecules, absorbing electrons and giving off oxygen gas and hydrogen ions: 2H2O → O2 + 4H+ + 4e–. ATP and NADPH then go on to take part in the light-independent (or ’dark’) reactions, of the Calvin cycle.The Calvin cycle is a circular series of reactions that use the energy-carrying molecules (ATP and NADPH) created in the light-dependent reactions to ‘fix’ carbon dioxide into organic molecules.In the Calvin cycle, one CO2 molecule reacts with ribulose bisphosphate (RuBP), a molecule with five carbon atoms, adding one carbon atom to create two molecules of glyceraldehyde 3-phosphate (GA3P), containing three carbon atoms each. Five of every six molecules of GA3P produced in the cycle are used to regenerate RuBP. Five molecules of GA3P (with three carbon atoms each) create three molecules of RuBP (with five carbon atoms each). The sixth molecule of GA3P is used to create glucose. Two GA3P molecules create a single molecule of glucose containing six carbon atoms. The energy-carrying molecules ATP and NADPH drive the series of reactions forward.
The Calvin Cycle: this diagram shows you where each ingredient in the production of glucose enters the cycle
How Do Plants Make Use of Their Glucose Supply?
The glucose created during photosynthesis provides the energy for all the other cellular processes in the plant. Plants can transport glucose to where it is needed via a second type of vascular tissue called phloem. Xylem carries water and minerals up to the leaves to be used in photosynthesis, and phloem carries glucose back to other parts of the plant. The xylem and phloem together form the ‘veins’ in the leaves and stems of plants.When glucose reaches the cells, it can be used to release energy, taking in oxygen and releasing carbon dioxide and water in a process known as respiration. This process takes place in organelles called mitochondria. Mitochondria are found in nearly all cells in both plants and animals. Respiration generates more of the energy-carrying molecules ATP and NADPH, which are then used to drive other cellular reactions. Because respiration consumes the glucose and oxygen created during photosynthesis and releases carbon dioxide, water, and energy, it can be thought of as the ‘opposite’ of photosynthesis.
Carbohydrate Synthesis and molecules effect
As well as functioning as an energy source used for respiration, plants can use glucose to create more complex carbohydrates, such as starch and cellulose, and a range of other molecules. Both starch and cellulose are made of long chains of glucose molecules joined together.
Cellulose: Cellulose is made of long, straight chains of glucose molecules. Cellulose chains join together to make long, strong fibers. These fibers form the cell walls that surround plant cells, which make them rigid and strong. Cellulose can’t be digested by animals, and so it forms a large part of the fiber content of your food. Although cellulose is carbonized during roasting, much of the structure of the cell walls remains intact. This structure determines the way coffee beans shatter during grinding. If the individual cells in the seeds are smaller, the beans will be harder and denser as a result. Some cellulose also breaks down during roasting to create citric acid. (T Nakabayashi, 1978.)
Starch: When glucose molecules are joined together in a different way, they form starch. Starch consists of branched chains of glucose molecules. At the end of each branch, glucose molecules can be added or removed as needed, which means starch can function as a glucose storage molecule. Starch is stored in all plant cells but especially in fruits, seeds, rhizomes, and tubers, and near the tips of branches, to prepare for the next growing season. Little if any starch is present in coffee beans.
Proteins: Plants use glucose, combined with nitrates from the soil, to create amino acids, the ‘building blocks’ of proteins. Nitrates in the soil are thus essential to plant growth. Nitrates occur naturally in soil; they are created by bacteria and during lightning strikes. Adding extra nitrates to the soil, in the form of organic matter (compost) or chemical fertilizer, can speed up plant growth considerably. The sulfur atoms found in proteins are an important part of many molecules responsible for the aromas of coffee. For example, certain mercaptans have a characteristic smell of roasted coffee.
Sucrose: Glucose can be converted to fructose, which joins to another molecule of glucose to create sucrose. Sucrose is the sugar that makes fruits taste sweet, enticing animals to eat the ripe fruit and thereby spread the mature seed. Sucrose in coffee seeds breaks down during roasting, taking part in caramelization and Maillard reactions to create many of the molecules responsible for coffee’s complex flavor. The sucrose also factors in the production of organic acids, including acetic and lactic acids.
Lipids: Glucose is also converted into lipids (fats). Lipids are a concentrated form of energy storage in plant seeds, and they support the growth of the seedling. Lipids in coffee include terpenes, which are responsible for some highly desirable flavor attributes (for example, limonene) and are thought to be responsible for some of coffee’s health benefits.
