How an Animal Cell Survives
Although the animal cell is similar in many ways to eukaryotic as well as some few eukaryotic cells, there are strikingly large differences between them, especially the requirements for survival in various environments (Baitsell, 2008). The animal cell is one of the members of eukaryotic cell category, whose structure is quite complicated by the organelles present as well as the diverse functions they play towards the survival of the cell and the organism in general (Solomon, Berg, & Martin, 2004). The cell structure is defined by a plasma membrane that bounds a number of organelles, all of which function towards the survival of the whole cell in the prevailing environment (Baitsell, 2008). Thus, it is important to perceive the cell as the unit of survival for the organism. A key to understanding the method of survival for the cell is the review of the functions of the cell, the organelles, as well as the meaning of life for the animal cell (Cyganiewicz & Moryl, 2005). It is thus arguable that survival for the animal cell is highly dependent on the processes of life of a single cell; the cellular complex, nutrition, respiration, digestion, reproduction, and growth process. All of these have some major function or role on how an animal cell survives.
The meaning of life in animals
In the scientific view, the animal cell is the basic building block for the whole organism. Thus, the meaning of life for a single cell is taken to mean the life of the entire organism (Solomon, Berg, & Martin, 2004). Thus, in scientific perception of an organism, the cellular life is defined as having properties that provide it with a clear difference from anything else (Cyganiewicz, & Moryl, 2005). The key is to note that the animal is cellular, and is either a single celled animal or composed of a number of cells. Life in an animal cell is encoded in a set of instructions which direct the way all the other organelles, the cell, the organs and the organism itself behave or work towards its survival (Cobb, 2011). These set of instructions are bounded within the nucleus of the cell, and are stored in the long complex molecule known as the DNA (Tropp & Freifelder, 2007). Thus, it is important to take the DNA as the main functional unit of life in an animal cell (Cyganiewicz & Moryl, 2005). The instructions stored in the DNA are effected by a long process of transcription, translation and effect of the transcription products, which then direct the survival of the cell and the animal in general (Solomon, Berg, & Martin, 2004). The process is quite long and complicated, but generally involves the translation of the set of codes stored in the DNA from its coded form to the functional proteins in a process known as the central dogma of molecular biology (Cobb, 2011). A number of enzymes are involved in this process, as do other components of the cell such as the ribosome, the proteins and other enhancers (Tropp, & Freifelder, 2007). The cellular life is therefore held within the DNA and the process of translation of the code of life to the specific instructions through the central dogma of molecular biology (Cobb, 2011).
The cell theory in relation to cellular life
The scientific proof that the cell is the functional unit of life is understood through the review of the structure and functions of the cell as described in the cell theory. According to the cell theory, the anima cell is composed of three major parts; the plasma membrane, the cell cytoplasm and the genetic code (Lee, 2007). The cell membrane is the protective part of cellular organelles and the genetic code, and thus it is taken to mean that it is the protective part of cellular life (Cyganiewicz, & Moryl, 2005). It is the outer part of the cell, which protects the inner parts from mechanical, chemical and biological damage, while at the same time acts to provide a pathway through which the cellular components communicate with the extracellular part and the other cells within its environment. The environment could be other cells in the organism for the multicellular animal or it could be the immediate environment for the single celled animals (Lee, 2007). The membrane itself is a highly developed part of the cell. It is made up of several components; proteins, lipids and cholesterol (Magner, 2002). The bulk of the membrane structure is made up of a bilayer of phospholipids, a fatty acid-protein structure that houses the cellular components. Other proteins exist within the cell membrane, including the proteins, the cholesterol as well as several ions. The proteins are divided into integral, transmembrane and surface proteins. Integral proteins act as the structural part of the membrane, which provide the support necessary for the membrane in order to house and protect the entire cell. The transmembrane proteins act as both the transport channels and structural components of the membrane (Tropp, & Freifelder, 2007). They provide a pathway through which the cells communicate with the extracellular parts, through the exchange of a number of compounds an d other items (Spilsbury, & Spilsbury, 2004). The surface proteins are found on the outer part of the cell, and act as the antigens or specialized surfaces through which foreign substances attach and enter the cell or produce some effect on the cell. It is important to note that the foreign substances might be other undesirable things such as the pathogens which also target and attach to the antigen proteins and either enter the cell or produce some undesirable effects on the cells (Magner, 2002).
The cytoplasm of the cell is the bulk fluid that resides in the large compartment of the animal cell. It is contains the cytosol where the bulk of the cellular components are found suspended or attached to others. It has the function of providing the organelles with a good environment at which they function in the optimum. The life processes are carried out in the organelles, which include the protein synthesis, metabolism and reproduction, implying that the cytoplasm houses and protects these processes (Magner, 2002).
Nutrition as it relates to cell life
Animal cell require a number of external products for the development of all the organelles as well as to carry out the functions of the cell for the organism survival. Nutrition is the major source of all these cellular requirements; which is the provision of the cellular requirement from the environment (Spilsbury, & Spilsbury, 2004). The cells obtain their requirements in form of molecules and chemical elements, compounds and other substances. Proteins are obtained inform of amino acids, peptides, and simple proteins (Solomon, Berg, & Martin, 2004). They are used to make several intracellular as well as surface and membrane proteins. The major intracellular proteins include the proteins involved in cellular activities such as those attached to the ribosomes, the endometrial reticulum, the lysosome and other structures. In addition the protein translates of the DNA code are made up of proteins, synthesized with information from the DNA codes (Tropp, & Freifelder, 2007). These proteins and amino acids must be provided from the environment if the animal cell is to remain functional, and thus in life. Nutrition is therefore the process of providing the animal cells within its requirements in order to support the life (Baker, 2008).
Photosynthesis and cell life
Animal cells do not produce nutrients of their own; rather they need to obtain it as nutrients from the environment. The fact that they must get these substances from the environment means that there is some importance of the phosynthetic cells, mostly the plants cells, in the survival of the animal cells. Photosynthesis is the process through which cells with chloroplasts synthesis carbohydrates from the material they intake in the presence of sunlight. In this way, they produce the food for the plant as well as for the animal cells in one way or the other.
Digestion and cellular life
The process of digestion is the key to the functioning of nutrition in animals. Digestion is the process by which the nutrients obtained from the environment into the anima are broken down from their complex state to simple molecules that can be utilized by the animal cells in order to maintain life. Digestion requires diverse involvement of organs, cells organelles in order to enhance the provision of cells with their requirements (Cobb, 2011). The nutrients are generally in form of three major forms, the carbohydrates macromolecules, the proteins and the lipids, the carbohydrates must be broken down to such simple sugars as glucose for production of energy needed to drive all other processes. They are treated in number of ways depending on the requirement and the abundance. Proteins are broken down in to simpler substance such as the peptides or into their simplest form of amino acids before being used by the cell to support cellular life. The lipids are either used as they are or may be broken down into their simple form of glycerol and fatty acids. The cells generally use these substances towards supporting the life of the organism.
Metabolism and life
Cells require energy in all their processes. The energy is provided by the nutrients taken from the environment. However, the energy must be obtained from the molecules through a complex series of processes known as the metabolism or respiration. Respiration implies that the cell obtain their energy requirements from the conversion and interconversion of the nutritional molecules from one form to another (Baker, 2008). A number of enzymes are also involved in the entire process (Solomon, Berg, & Martin, 2004). The process of glycolysis is the most important but quite complex pathway through which the cells obtain energy as the glucose obtained in nutrition is converted and interconvert to other molecules such as pyruvate, releasing energy. These processes cannot be effect without the role of enzymes such as oxidases and reeducates and which are enhanced by proton carriers such as NAD and FADH (Baker, 2008). The Krebs cycle is an important pathway through which all the cells obtain energy through conversion of substances to release some form of energy in different stages (Cobb, 2011).
Genetics and life
Cellular life is highly dependent on the genetic makeup as described by the central dogma of molecular biology (Spilsbury, & Spilsbury, 2004). The continuation of cellular life depends largely on the sharing of genes between the cells in one generation and the nest generation, reproduction thus comes in, and reproduction is the process by which organisms give rise to another organism of their kind. In animals, this is done through mating, a process by which a female and a male organism mate and share their pass some of their genes to the new organism. The process of passing the genes from one organism to another is explained by genetics, animals have two types of cells in their bodies; gametes and somatic cells (Cyganiewicz, & Moryl, 2005). The difference is that the gametes are the reproductive cells, whose genetic makeup is normally half, while the somatic or body cells have their full genetic makeup. Once the organism mate, the gametes combine their half genetic make ups to develop a new organism with the full genetic makeup, each half derived from both each of the mating parents. This further provides the new cells with a variety of genes or biological codes of life in the DNA, which further code for the instructions that enhance the survival of the cells (Cyganiewicz, & Moryl, 2005).
Mitosis and meiosis in relation to cell survival
The animal cell must divide to give rise to a new cell of its kind if the generation is to survive in the environment. This is affected by the process of cell division and multiplication, looking at animal cells, it is important to note that the two types of cells mentioned above; somatic and gamete cells are quite different in terms of the genetic makeup in their nucleus. This difference further implies that their method of occurrence and is not very similar. There are two distinct processes through which the animal cells divide; mitosis and meiosis. In mitosis, the cell undergoes a four stage process, prophase, metaphase, anaphase and telophase. In this process, the genetic material as well as all other parts of the cell is divided into two similar functional components, culminating into the division of the entire cell into two distinctive cells. The two cells have a full genetic makeup, made up of 46 chromosomes in humans and varying number in other animals. However, the process is quite different t in meiosis. This is because it is the process through which reproductive cells, the gametes divide to give rise to new xcells, in this process, the cells divide into two cells in the four stage procedure, but the result is that the two resulting cells only receive half the number of chromosomes (the genetic makeup) from the mother cell. This ensures that the cells will have a potential to combine with another cell during the fertilization, producing a cell with the full genetic makeup.
So what is the relationship of these processes to the life of the organism?
It is important to conclude with a review of how all these processes are connected or relate to each other in the process of maintaining life for the animal cells (Baker, 2008).. The cell theory provides an insight into the structures and functions of the cellular components work with instructions from the genetic material stored in the nucleus of the cell (Solomon, Berg, & Martin, 2004). The genetic information cannot be effective without translation, which further requires both energy and proteins. These proteins as well as energy are provided through nutrition and digestion, the ingested materials are first broken down to the simple forms, and then used to make the cellular components as well as provision of protein molecules for the translation of genetic code (Baker, 2008). In addition, all these processes require energy, which is in turn provided by the process of metabolism and respiration (Cyganiewicz, & Moryl, 2005). The genetic makeup is developed from the genetic combination of gametes in the process of reproduction (Spilsbury, & Spilsbury, 2004). Moreover, all these processes are driven and enhanced by hormones as well as other enzymes, all of which are proteins synthesized with instructions from the genetic material. Thus, the maintenance of cellular life is highly complicated, and is not just a simple hierarchical line o0f functions, but a highly interconnected system (Cyganiewicz, & Moryl, 2005).
References
Baitsell, G. A. (2008). The cell theory: a modern concept of the cell as a structural unit. Mason, OH: Cengage learning
Baker, J. (2008). The cell theory: a restatement, history, and critique. London: Garland.
Cobb, A. (2011). The cell theory. New York: Facts on File.
Cyganiewicz, P., & Moryl, F. (2005). The cell theory. London: Pendulum Press.
Lee, F. K. (2007). Cell scientists: discovering how cells work. New York, Springer.
Luisi, P., & Luisi, P. L. (2008). The emergence of life: from chemical origins to synthetic biology. Cambridge, UK: Cambridge University Press.
Magner, Lois. (2002). History of the Life Sciences. New York: CRC Press.
Solomon, P., Berg, L., & Martin, D. (2004). Biology. Mason, OH: Cengage Learning.
Spilsbury, L., & Spilsbury, R. (2004). Life Processes: From Reproduction to Respiration. London: Heinemann Library.
Tropp, B., & Freifelder, D. (2007). Molecular biology: genes to proteins. London: Jones & Bartlett Learning.
