A cell is the basic structure of any living thing, and thus can be considered the basis of life. All life is made up one type of cell or another. A notable thing about living systems is their ability to maintain a comparatively constant state known as homeostasis. The cell happens to be the earliest level of complexity capable of maintaining homeostasis, and manages to perform this critical function thanks to its unique structure. According to the current cell theory, all living things are made up of one or more cells, with new cells being formed through the division of pre- existing cells into two. Any function that is essential to life occurs inside the cell. A cell transfers to the next generation any information needed to carry out and regulate its function through a process called cell division.
Each cell is made up of three components: a cell membrane, the cytoplasm, and organelles. The membrane is a structure surrounding the cell that acts as a boundary between its internal and external environment. It is quite a critical component as it controls what gets into or out of the cell. The cytoplasm is the cell’s watery interior containing organelles, ions, and proteins. Organelles conduct all the activities needed for the cell to grow, reproduce, and live. In a living thing, cells make up a kind of an organization between tissues and organelles. Tissues are groups of specialized cells while organelles are collections of specialized macromolecules. Tissues are not all the same and differ from each other in terms of the function and structure of their constituent cells. Hence, the cells making up each type of tissue vary in size, interior structure and shape in order to facilitate their assigned physiological function inside the tissue. The nucleus is a spherical organelle that serves as the cell’s information center. It is surrounded by the cell membrane and makes up about ten percent of the cell. The nucleus serves two functions, the most important one being holding the genetic material known as DNA (deoxyribose nucleic acid). It also coordinates the cell’s activities such as growth, reproduction, energy conversion, and protein secretion. The cytoplasm is a jelly-like matrix that contains organelles such as the sugars, amino acids, and proteins used for cellular growth and reproduction. It serves a number of crucial cellular functions such as facilitating movement, conducting electricity, and dissolving waste products. The network of filaments found in the cytoplasm gives the cell its shape.
Cell production is a process through which a cell divides to create new cells. Every time a cell divides, it makes a copy of tightly coiled DNA strands known as chromosomes. It then sends identical copies of the chromosomes to the newly created cells in a process known as mitosis. A chromosome is made up of two halves known as chromatids that are divided at their middle by a centromere. During mitosis, such a structure is attached to the spindle fibers in a way that pulls a chromatic to each cell side when it divides. Chromosomes also happen to be part of a homologous pair containing genes that control the same trait.
Cellular respiration and photosynthesis are processes carried out by most living things in order to get usable energy from nature. Most plants perform photosynthesis whereby they make their own food, while most animals utilize cellular respiration to fulfill their energy requirements. Photosynthesis is a process through which plant transform light energy into chemical energy to create carbohydrate molecules like glucose that are full of energy. Cellular respiration is all about the breakdown of food molecules to make energy that is stored in the form of ATP (adenosine triphosphate) molecules. Once plant cells create sugar molecules via photosynthesis, they undergo cellular respiration to form ATP molecules. On the other hand, animals get food molecules from plants and then endure cellular respiration so as to get ATP molecules. Any living organism used such stored ATP molecules to conduct their metabolic processes.
When traits are transferred from one generation to another, they tend to follow genetic inheritance principles defined by a scientist called Gregor Mendel during the mid-19th century. Mendel’s first law is known as the principle of segregation. It states that the two members of a gene pair called alleles tend to separate from one another to form gametes whereby half the gametes carry an allele while the other half carries the other. Mendel’s second law is called the principle of independent assortment. It states that the manner in which an allele pair is separated into two daughter cells does not affect how another pair is segregated. Mendel’s principles are based on an assumption that one allele in a pair is dominant to the other.
Cancer is a condition that results from a gene mutation or a dramatic change in how genes are regulated. Gene activation or silencing is a processes through which many proteins are either turned on or off in a way that significantly changes a cell’s overall activities. A gene that is usually not expressed in that particular cell can get switched on and then expressed at rather high levels. It is possible to detect changes in transcription, epigenetic regulation, protein translation, RNA stability, and post-translational control in a cancer case. Such changes may not occur at the same time in one instance of cancer. However, changes taking place at every one of these levels can be noticed when observing cancer in different individuals at different parts of their bodies. Scientists are trying to figure out the common changes that result in certain types of cancer or how a certain modification can be exploited to do away with a tumor cell.
- Akçay, S. (2017). Prospective elementary science teachers’ understanding of photosynthesis and cellular respiration in the context of multiple biological levels as nested systems. Journal of Biological Education, 51(1), 52-65.
- Freeman, J. (2017). History and Anatomy of a Cell. Microreviews in Cell and Molecular Biology, 2(2).