The two major process, photosynthesis, and cellular respiration have been considered as vital metabolic possess which play a critical role regarding sustaining life on earth. At one hand, cellular respiration is the metabolic reaction occurring in an organism’s cells for the conversion of biochemical energy from the nutrients to adenosine triphosphate (ATP), while at the same time release wastes (Brown & Schwartz, 2009). On the other hand, photosynthesis is a process whereby plants, some proteins, and bacteria make use of sun’s energy to generate glucose using water and CO2. The glucose produced is then changed to pyruvate that further produces ATP using cellular respiration, and in the process, O2 is formed.
The two processes further have been argued to play a significant role regarding continuous energy cycle critical to sustaining life. Both cellular respiration and photosynthesis have various stages in which production of energy takes place, and at the same time, they have a different relationship with the organelles situated in eukaryotic cells (Brown, 2000). Further, the two processes are critical in the way life has evolved and diversified as it is today. Despite the fact that both photosynthesis and cellular respiration are distinct regarding their procedures, they seem significantly interdependent to one another and at the same time exhibit complementary cycle. According to Brown & Schwartz, (2009), cellular respiration converts glucose into energy. In addition to this, cellular respiration comprises of several series of reactions as shown in the chemical equation:
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C6H12O6 + 6O2 → 6CO2 + 6H2O + Chemical Energy (in ATP)
The above process often takes place in every living cell and occurs in the heterotrophs and autotrophs' cell. Cellular respiration can further be viewed as the exchange of oxygen to facilitate the breakdown of fuel referred to as aerobic process. The process is carried out be cell exchanging gases with their adjacent surrounding to produce adenosine triphosphate that is ultimately utilized by cells as the primary energy source (Wegrzyn et al., 2009). It is accomplished via various reactions and can be considered as a good illustration of the metabolic pathways. Within cellular respiration, the chemical energy released by fuel molecule is changed into ADP. Further, ADP further combines with phosphate converting cell’s energy into ATP. In the event the ATP is spent by the cells, it then releases another form of phosphate that also joins with the ADP to start a new cycle. In overall, the cycle occurs in three primary phases including citric acid cycle, electron transport and glycolysis (Brown, 2000).
The metabolic pathways which form within a cytosol are the Glycolysis where a glucose molecule significantly separates to pyruvate two molecules and takes place at cytoplasmic fluid (Brown & Schwartz, 2009). The glucose molecules are broken down into half creating two three-carbon molecules utilizing the ATP molecule. The divided carbon molecule further offers electrons to NAD+ that further helps to create NADH then consequently create four more molecules of ATP. After that, the pyruvic acid further loses one carbon molecule and change to Acetic acid then begins the citric acid cycle a process that breaks down glucose to CO2 as waste (Von Caemmerer, 2000).
The enzyme that is used in completing this process then dissolves with mitochondria, and in the process, it recycles at the molecular level releasing NADH through oxidation of the fuel. In the process, CoA is produced as the acetic acid molecules that had remained attached to the molecule called "coenzyme A" transported to the citric acid cycle first reaction (Brown, 2000). Further, the CoA is eliminated from the recycles to re-attach to the other available acetic molecules. Throughout the cycles, acetic acid will combine with the carbon molecule forming citric acid. Every time the molecule begins the entire cycle as fuel more carbon dioxide molecules are produced as waste, and the whole procedure is carried out for the glucose molecules.
According to Wegrzyn et al., (2009), electron transport is the third phase of the entire process where electron obtained by the reaction completed in the initial two phases moves down the chain of the carriage to O2. In the mitochondria’s inner membrane, is where the protein and the molecule are situated. According to Von Caemmerer, (2000), the released energy produces ATP at the transport process. Further, there is the production of the smaller amount of ATP throughout the first two stages. The ATP is the major aspect of the process, and some of ATP are produced in each stage and then simultaneously spend at every phase creating a self-sustaining cellular cycle of energy generation and utilization.
Photosynthesis evidently has some similarities to the cellular respiration where it is also a means for energy generation. Cellular respiration is specifically accomplished by particular types of plants and animals through changing organic molecule and food to a form of energy, but photosynthesis, on the other hand, converts energy from the sun to chemical energy meant for the bacteria, algae and even plants (Wegrzyn et al., 2009). Photosynthesis often occurs in the organelles referred to as chloroplast. The organelles are in a position to absorb sunlight and typically are situated within the leaves. Within the leaves, there exist smaller pores referred to as stomata where the CO2 enters the leaf and O2 emitted. According to Von Caemmerer, (2000), as is the case with animals, photosynthesis process requires water absorbed via the roots then transported to the leaves. The stomata can thus be said to be the most important piece of the entire photosynthesis process since it is where CO2 enters and O2 exit.
According to Von Caemmerer, (2000), the reverse of what the cellular respiration exhibits occurs in photosynthesis where it combines with water and CO2 molecules acquired from the plant’s roots and then use sunlight energy to complete the chemical reaction where it produces energy and waste products. The wastes of photosynthesis are oxygen and glucose. The byproducts are thus what are needed by the cellular respiration to function, and this significantly completes the life cycle. In the photosynthesis process, the energy from the sun changed chemically and bonds with the molecule of carbohydrate and transformed into ATP molecule. The form of energy found in the ATP is used to enable the entire process to repeat consistently within cells and is often completed in two different phases including the Calvin cycle and light reaction (Wegrzyn et al., 2009).
Within the first phase, the light reaction step, sunlight energy is taken into the chlorophyll membrane and converted to ATP then electrons carry the NADPH. According to Von Caemmerer, (2000), water is specifically broken down once electrons are eliminated from the NADP+ that produced NADPH and in the process O2 is further removed as waste in the form of gas. Immediately the first stage is completed, Calvin cycle starts (Brown, 2000). During this second stage, the light reaction results provide the cells with energy to generate fuel or even sugar from CO2. With the use of ATP, it is in a position to synthesize sugar and enzyme responsible that gets absorbed in the stomata within the chloroplast. Each time the cycle is accomplished; sugar is generated in addition to the NADP+ and ADP with additional phosphate groups which further combines with water and begins the light reaction phase which kicks off the cycle once again.
According to Von Caemmerer, (2000), it is important to note that both photosynthesis and cellular respiration major relies on the important organelles found in the eukaryotic cell complete the tasks. There are also certain differences in the manner in which the living things, fungi and the plants go about to obtain energy and thus make use of the organelles within the eukaryotic cell. The mitochondrion is where the pyruvates enter and start the cellular respiration process to generate energy; however, plants do not need to have these organelles since light to energy conversion is completed by photosynthesis by the chlorophyll.
There exist numerous vital areas where the two processes deal with to establish a life’s balance in the ecosystem. Both cellular respiration and photosynthesis can be said to be interconnected since they generate energy used by plants and further, they recycle the wastes produce by each other for their use (Wegrzyn et al., 2009). For instance, the man inhales O2 which helps in keeping the cells alive and further, through the process of cellular respiration, they exhale CO2 as the byproduct. The plants absorbed the carbon dioxide released and through photosynthesis process, convert the light energy and using cellular respiration, O2 is released as the waste product that is recycled by the plants and animals to start off a new process. Therefore, such a complementary reaction substantially plays a core function of sustaining life in different levels (Brown, 2000).
Based on the ideas of Darwin, cells tend to evolve according to the environmental needs to be able to survive. Most of the plants are in a position to complete the photosynthesis process and in the process draw CO2 directly from the air. Further different methods are used by plants in both dry and hot climates to enhance their survival giving them the capability to generate oxygen for the existence of life (Von Caemmerer, 2000). Before the Calvin cycle process begins, certain plants tend to have diverse approaches to deal with carbons. For instance, C4 plants often ensure their stomata are closed at all time, and this often depends on variations of climatic condition and further, they have more enzymes that enable them to absorb CO2 into their process continuously. The example shows how a plant can fully adapt to its environment that might have been destructive to the chemical reaction that plants undergo to generate oxygen and energy. The natural selection ensures that individual plants can manufacture their food and offer the benefits of air and food to the rest of the living things.
References
Brown, D. S. (2000). The effect of individual and group concept mapping on students' conceptual understanding of photosynthesis and cellular respiration in three different academic levels of biology classes .
Brown, M. H., & Schwartz, R. S. (2009). Connecting photosynthesis and cellular respiration: Preservice teachers' conceptions. Journal of Research in Science Teaching , 46 (7), 791.
Von Caemmerer, S. (2000). Biochemical models of leaf photosynthesis . Csiro publishing.
Wegrzyn, J., Potla, R., Chwae, Y. J., Sepuri, N. B., Zhang, Q., Koeck, T., ... & Moh, A. (2009). The Function of mitochondrial Stat3 in cellular respiration. Science , 323 (5915), 793-797.
