Biology

Life of any organism is a complicated and compound process. Organism depends on the several properties of life that ensure its functioning in the environment. Burkett (2006) names six main properties of life, which are compulsory for every living organism. The first important property of life is cellular organization because all organisms have one or more cells. The second one is homeostasis that is vital for all organisms. An organism has to be able to regulate and maintain its internal environment during any changes in the external environment. Another property of life is irritability; it is the ability of an organism to respond to pain, pressure or any other exposure of external factors, such as sound, light, etc. The fourth property of life is reproduction. Reproduction is a vital ability for all organisms, as well as growth and growth and development since an organism is able to product new cells and pass hereditary information on to its offspring (Burkett, 2006). Then, any organism has to obtain and use energy that is of paramount importance for the functioning. This ability is called metabolism and it is the main chemical activity for cells and more complicated organisms. Finally, the last property of life is evolution. All organisms must be able to adapt to the environment and evolve at the same time. Cell is the simplest and smallest element of life. It consists of three major elements; they are a cell nucleus, cytoplasm, which connects all structures of a cell, vacuole, replenish and maintain useful elements, and a cell wall, which protects and supports the structure of a cell.

However, the vital activity of cell may seem to be simple; cell has a much more complicated organization and requires the same vital processes as more compound organisms. Cellular respiration is a total of enzymatic processes, which lead to the split of carbohydrates, fatty acids and amino acids into carbon dioxide and water. It allows to supply a cell with the nutrient energy. Cellular respiration is a vital process because all cells waste energy for growth, movement, irritability, reproduction and other properties of life. Photosynthesis is an ability of green plants and some microorganisms to produce energy in the sunlight. This process results in manufacturing food from carbon dioxide and water with the help of sunlight. At the same time, photosynthesis is a compound and complicated process. Stone (2004) states that “photosynthesis makes a vital connection between the sun and the energy needs of living systems”. Actually, it provides plants and other organisms with endless source of energy. However, one of the most significant functions of a cell is reproduction. Cells reproduce by the division of one cell into two or more cells. Prokaryotes divide into two cells when the main cell becomes longer that leads to creation of two daughter cells. Eukaryotes have two types of cell division, and during its division organoids and cytoplasm separate from old cells to new daughter cells. Meiosis is a type of cell division, which enables the reproduction of cells. At the same time, during meiosis the number of chromosomes reduces twice. In opposition to meiosis, during mitosis cells divide into its duplicates or cells with the similar contents.

Mendel laws are the principles of transmission of hereditary characters from parents to offspring. Mendel found out that the peas in his garden had certain characteristics (Stone, 2004). It provoked new studies about traits between organisms and stimulated the establishment of the new science – genetics. Mendel also discovered that organisms could possess dominant or recessive factors of inheritance that influence its further offspring. When maternal organisms had two similar factors, hybrids of the first generation obtained one factor from every parent without any fusion of these factors. Thus, it was found out that every character of an organism is controlled by the pair of genes. Mendel’s laws also allowed to realize the significant role of a cell nucleus and chromosomes in transmission of hereditary characters. DNA is a macromolecule, which provides a storage and transmission of genetic program from the maternal organism to daughter one, that is a vital aspect for functioning of all living organisms. Additionally, it includes the information about proteins and RNA structure. Therefore, DNA influences two main features of the living organisms such as inheritance and evolution. Due to DNA, organisms are able to grow, develop and reproduce. It consists of repeating units, which are called nucleotides; DNA looks like a two chains coiled up around the same axis. Nucleotides are combined into long polynucleotide chains, which unite into double spiral. The framework of each chain consists of phosphates and sugars.

Cancer is caused by retroviruses “when they enter the nuclei of normal cells” (Stone, 2004). Retroviruses promote the division and destruction of cells that is characteristic for cancer. Cellular genes, which were inactive before viruses entered a cell, become active and lead enormous growth of infected cells, and these genes become oncogenes. The growth of infected cells goes out of control and cancer leads to mutation. Mutation results in extreme changes of DNA sequence of a cell. DNA of infected cell also duplicates the codes of a healthy cell or removes it. Finally, cells stop to grow normally, and their abnormal growth negatively influences the life of an organism and leads to its consequent deformation and destruction. Healthy cells also get infected by the oncogenes. Cancer leads to total destruction of host cells. One of the most difficult challenges in curing the cancer is that oncogenes completely resemble normal genes. This prevents normal genes from stabilization and repairing infected genes. Cancer is a disease that breaks the regulation of cells’ growth and gene control.