The Cell - Essay Example

The Cell Organisms comprise of cells that defines the cells as be the basic unit of life in terms of structure. Each organism bears one or more cells where some are highly organized, some complex while others are coordinated to perform specialized functions (Guttman, 2011). However, the living organism has distinct characteristics that include evolution, growth and development, mechanisms for energy production, response to stimuli, and regulation. Life is well defined by the functions of a living organism in an ecosystem. Cells arise only from pre-existing cells mainly during reproduction and cell division. The type of cells includes prokaryotic and eukaryotic cells. Prokaryotic cells are primitive compared with eukaryotic cell where bacteria are good example (Barton, 2005). They have no nuclear membrane, no membrane-bound organelles and have uniform cytoplasm. Eukaryotic cells are present in higher living organisms such as plant and animals. They are highly specialized with membranous structures and possess a membranous nucleus. The nucleus contains the genetic material that is transferred to the offspring during reproduction. Nucleus as well controls cell activities and regulate the pattern of growth (Sinden, 1994). DNA (Deoxyribonucleic acid) is known to be the primary genetic material where all other cell molecules are made, and it is located in the nucleus. For an instant, protein biosynthesis begins with DNA during replication, transcription and then followed by the translation. Protein biosynthesis occurs in the ribosome where translation takes place with the help of mRNA. The ribosomes synthesize other enzymes that are vital for growth (Guttman, 2011). Cell membranes are semi-permeable and only allow certain materials to pass through in and out and not others. They are made up lipid bilayer that is embedded with protein. The lipid bilayer has polar ends on the outer surface while aminoacyl group are inside since they are non-polar. Some cell membranes are complex like in gram-positive bacteria that have a hidden peptidoglycan for antibiotic resistance (Barton, 2005). Cell walls are present only in plants and mainly regulate the osmotic balance apart from controlling the passage of materials. There are two types endoplasmic reticulum. The smooth endoplasmic reticulums have no ribosomes on their surface, and they carry out the synthesis of lipids. On the other hand, rough endoplasmic reticulum bears ribosomes on its surface hence it takes part in the synthesis of proteins. Another organelle is the Golgi body whose primary function is to transport membrane-bound vesicles. The chloroplast is a double membrane cell organelle that is only present in plants. The Lysosomes are organelles that carry out hydrolysis by breaking down various macromolecules hence they are digestive in nature (Seong, 2004). The chloroplast possesses light pigments known as chlorophyll whose primary function is to trap light energy during the process of photosynthesis. The mitochondria also have a double membrane, and they are the site for respiration. The inner membrane is highly folded to increase the surface area for enzyme action. Respiration is important processes that provide the cell with energy in the form of ATP. Photosynthesis is the process in which green plants utilize light energy in the breakdown of carbon dioxide and water to produce glucose for plant use (Donald, 2015). Photosynthesis has the light stage where hydrogen molecule from water is used to reduce NADP to NADPH, and one molecule of ATP is used. The next is the dark stage that relies on the use of enzymes to break down carbon dioxide to produce glucose. In respiration glucose is metabolized to yield ATP, which is an energy source for organisms (Donald, 2015). Glycolysis is one of the phases of cellular respiration in which the cell break down glucose to pyruvic acid. The pyruvic acid is then oxidized to form water and carbon dioxide. On the other hand, reproduction involves the use of specialized structures in multicellular organism to produce offspring. During the reproduction process, the genetic material is passed to the next generation that ensures the offspring have the same characteristic as a parent (Seong, 2004). In unicellular microorganism, reproduction is by cell division where a cell divides to form two equal daughter cells. Meiosis and mitosis are the primary processes of reproduction. Meiosis is specifically for sex cells wearers the mitosis is for the reproduction of somatic or non-gametic cells (Seong, 2004). The cells usually duplicate their genomic content during reproduction that is then transferred to each daughter cell. Asexual reproduction is by mitosis where two identical daughter cells are formed in somatic cells. However, sexual reproduction is by meiosis where sex cells or germ cells are produced and usually forms of four daughter cells that are genetically different. Gregor Medel deduced some classical genetic principles for inheritance. The principles relate to how parent transfer genes to their offspring or the transfer of genetic material from one generation to another. Medel’s laws include the Law of segregation where a gene pair defines each inherited trait. The sex cells only possess one gene in a pair; hence an offspring inherits a single gene from each parent. The next is ‘the Law of Independent Assortment’ which implies that traits for inheritance are not dependent on each other. The sorting of genes with the different trait is separate from one another. The Law of Dominance is the last one where if two alternate genes are present, the dominant one is expressed. From Mendel, different physical characteristics can be present in distinct combinations of different genotypes (Guttman, 2011). DNA refers to the Deoxyribonucleic acid molecule. DNA is a double helix structure and has two strands that run in opposite direction. The DNA is made up of with a phosphate group, deoxyribose sugar and nucleotide bases which include Thymine, Guanine, Cytosine, and the Adenine (Sinden, 1994). Chromosomes contain condensed form of DNA to allow its transfer to the offspring from the parents. However, the DNA may be as well be condensed in the chromatin for the transfer (Guttman, 2011). Cancer refers to the uncontrolled growth of cells mainly due to mutations of genetic content in the cells (Pecorino, 2012). The uncontrolled growth results in the formation of tumors where in severe cases result in the death of the individual. Cancerous growth should be detected early enough to be contained, and the cells can be restored. The gene control can be achieved through modification of the genome to counter mutated cells. Gene therapy can as well control gene expression. Recombination has been used in the repair of cancer cells where cancer cells are removed and then modified with normal genes. Use of drugs and chemicals also regulate gene expression that is referred as chemotherapy (Pecorino, 2012). The mutations in the cancer cells are the target by various methods for gene regulation. References Barton, L. (2005). Structural and Functional Relationships in Prokaryotes. New York: Springer Science & Business Media. Donald, R. (2015). Fundamentals of Anatomy and Physiology. New York: Cengage Learning. Guttman, B. (2011). Genetics: The Code of Life,Contemporary Issues . New York: The Rosen Publishing Group. Pecorino, L. (2012). Molecular Biology of Cancer: Mechanisms, Targets, and Therapeutics.UK: Oxford University Press. Seong, S. (2004). Cell Biology. New York: New Age International. Sinden, R. (1994). DNA Structure and Function. New Yolk: Gulf Professional Publishing. Read More