The cell is recognized as the basic unit of life. However, an organism or the body comprises other components precisely organized to confer the unique characteristics of life observed in different living things. Analysis of the human body among other living or nonliving things from a chemical point of view shows atoms as the smallest building blocks of an organism. Precisely, the total body chemistry of the body has been approximated to comprise 96% of common atoms such as carbon, oxygen, hydrogen, and nitrogen (Sherwood, 2008). The common atoms follow unique chemical combinations to form important molecules of life such as proteins, nucleic acids, carbohydrates, and fats. The nucleic acids form a critical molecule of life because it forms genetic materials such as DNA, which plays a critical role in determining the characteristics of an organism and other functions of the body (Sherwood, 2008).
As such, life arises from atoms and molecules organized in specific ways to bring out unique characteristics of life, some visible and others invisible to the naked eye. However, it is important to note that these inanimate ingredients of life are themselves nonliving chemical components that must be organized in unique ways to give forth life (Sherwood, 2008). The cell is recognized as the smallest but fundamental unit of life because of its role in influencing all the structural and functional processes associated with life. In this case, scientific research has shown the existence of single-celled organisms such as the amoeba which can be termed independent forms of life.
However, humans and plants are multi-cellular organisms whose structural and functional aspects are influenced by numerous cells. It is important to note that in some multi-cellular organisms such as a sponge, the cells are similar but in complex multi-cellular forms of life such as humans, several types of cells such as nerve cells, muscle cells, and gland cells combine to achieve the various structural and functional roles of a cell in such organisms.
The Basic Anatomy and Physiology of a Cell
A cell consists of three major parts, including the cell membrane, the nucleus, and the cytoplasm. In this case, every cell regardless of its type or form must have these three components or parts. The cell membrane or plasma membrane is a thin layer that encloses the other components of a cell as well as plays a critical role in the survival of the cell by regulating the movement of materials into and out of the cell (Sherwood, 2008).
The cell membrane consists of well-organized molecules known as phospholipids structured in the form of carbohydrates heads and lipid tails. The plasma membrane achieves the regulatory function through its selective permeability characteristic. The cytoplasm is the substance in which other cell organelles are found within the cell and play a critical role in the transportation of materials within the cell. On the other hand, the nucleus serves as the control center for all cell functions and consists of a nucleolus and the cell’s nucleic acid known as the DNA (Sherwood, 2008). The nucleus content is further enclosed by a nuclear membrane but with nuclear pores that allow communication with other organelles. The nucleus contains genetic information in the form of DNA, which is held in the cell by other nucleus organelles known as the chromosomes.
The cytoplasm consists of other organelles commonly known as cytoplasmic organelles such as the mitochondria, Golgi apparatus, lysosome, smooth endoplasmic reticulum (SER), rough endoplasmic (RER), and the ribosome. The mitochondria generate the energy necessary for the cell functions by converting sugars into ATP, a form of energy used by the cell for its functions. The lysosome on the other hand plays a protective role by destroying materials that may be toxic to the cell (Sherwood, 2008). Other than destroying potential toxic materials, the organelle also destroys and eliminates old organelles.
The ribosomes also play a critical in the cell by synthesizing the proteins needed by the cell for structural functions. The ribosome achieves this role by reading the DNA codes for the synthesis of the various forms of proteins required by the cell. The SER contributes to the survival of the cell through the synthesis of carbohydrates and lipids as some of the building blocks of the cell while the RER plays an important role in the protein synthesis of proteins by aiding the ribosome to attach to the DNA in the process of protein synthesis.
Cell Respiration and Photosynthesis
Cell respiration and photosynthesis are two important cell functions that take place in different parts of the cell with the latter taking place in the chloroplast while the former taking place in the mitochondria. The importance of cellular respiration is the production of energy from the molecules such as carbohydrates or sugars ingested by the cell necessary to carry out the various functions of the cell (Porth, 2011). However, photosynthesis takes place only in plant cells with chlorophyll as one of the key ingredients of photosynthesis and its main role is the manufacturing materials or food needed by the plant for its functions or storage. The process of cellular respiration involves breaking down glucose into carbon dioxide and water with the release of energy. The released energy is then converted into ATP as represented in as follows:
C6H12O6 + 6O2 6CO2 + 6H2O
The cellular respiration can be summarized into three phases including the glycolysis (the breakdown of glucose), the citric acid cycle (the formation of electron carriers), and the electron transport chain (the formation of ATP).
Cell reproduction occurs through a cell division process known as mitosis. The process of mitosis is crucial in ensuring the production of new cells needed for repair, replacement of older cells, and growth (Saltsman, 2011). The process involves the division of one cell into two complete independent cells but identical to the parent cell or original cell (Saltsman, 2011). The human cell goes through a 6-phase cell division process.
The DNA consists of nucleotides made up of phosphoric acid, deoxyribose (a five-carbon sugar), and one of four nitrogenous bases. The nitrogenous bases which determine or carry the genetic information are categorized into pyrimidine bases (thymine and cytosine) and purine bases ( adenine and guanine) (Porth, 2011). The four bases are organized into a double helix structure with base pairing.
Mendel’s Laws of Genetics
Mendel’s first law known as the segregation law states that for gametes to form the two alleles for a trait must separate and one parent passes only one allele for every trait to their offspring (Martini, Stephens & Read, 2013). On the other hand, the Second Law states that the genes for different traits are inherited independently of each other from either of the parents.
In conclusion, developments in the study of genes have seen the application of such knowledge in the control of cancer. Insights on the molecular mechanism of cancer development have seen the identification of novel downstream target genes such as the genes modulated by ACTR in the control of urinary bladder cancer. As such, the genetic control mechanism in cancer control aims at regulating or altering the expression of certain genes responsible for cancer development or growth.
- Martini, A., Stephens, D., Read, A. (2013). Genes, hearing, and deafness: From molecular biology to clinical practice. London: CRC Press.
- Porth, C. (2011). Essentials of pathophysiology: Concepts of altered health states. New York, NY: Lippincott Williams & Wilkins.
- Saltsman, K. (2011). Chapter 4: Cellular Reproduction: Multiplication by division. National Institute of General Medical Sciences.
- Sherwood, L. (2008). Human physiology: From cells to systems. Stamford, CT: Cengage Learning.
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