Introduction To Cell Biology

Cell Biology: An Overview Cell biology is the area of biology which deals with characteristics of cells – the structure and function of cells as basic units of life. Every living being is made up of cells, which include the ones that are individual like bacteria and the ones that are many-celled including plants and animals. Knowledge of the cells is significant for a better concept of life particularly diseases, growth and reproduction. 1. Structure of Cells Cells vary in size, shape, and function, but they all share certain basic structures: Cell Membrane: The cell membrane is a phospholipid bi-layer which surrounds the cell, it acts as barrier that separates the cell from the environment. It controls conductivity and selectively allows material to go in and out of the cell hence keeping the internal condition of the cell steady. Cytoplasm: Cytoplasm is semi fluid substance occupying the largest fraction of cell volume and possesses all the organelles. It is the scene of many cellular activities as well for the transport of molecules within the cell. Nucleus: The nucleus is the largest organelle in a cell and houses all the working cell’s hereditary material or DNA. It plays a critical role in controlling the rates of synthesis of genes and also the organization of cell operations including increases of growth, metabolism as well as the process of reproduction. Organelles: Organelles are the specialized structure found in the cell that has its specific role to play. Examples are Mitochondria which contained energy production, Endoplasmic reticulum involved in synthesis and transport of proteins and lipids, Golgi apparatus which is involved in modification and sorting of proteins, and lysosomes which degrades waste products. 2. Types of Cells Cells are broadly classified into two types based on their structure: Prokaryotic Cells: These are basic microorganisms which are single celled and are of the bacterial form. They do not possess a limit membrane, a nucleus and other conocentrically developed organelles. In prokaryotic cells the DNA is situated in the nucleoid area. Eukaryotic Cells: Eukaryotic cells are larger and more complicated and they range from the simplest organism, protist, fungi, plants as well as animals. They have a clear and evident nuclear area and are characterized by many membrane-bound organelles to carry out specific tasks. 3. Cellular Functions Cells perform various essential functions to sustain life: Metabolism: The metabolic reactions occur in the cells, anabolic and catabolic reactions which help nutrients to be changed into energy and new materials to replace the worn-out parts of the body. Protein Synthesis: Cell synthesises proteins, which are then used for the cell structures, performing their roles and coordination. This process includes transcribe (the process of copying DNA and converting it into RNA) and translate (the process of compiling proteins out of amino acids according to the code from the RNA). Cell Division: They also replicate by such methods as mitosis, which is to enable growth and repair of tissues in the body as well as meiosis which allows for sexual reproduction in higher organisms, so as to produce variation and keep alive the train of genetic heritage. Communication: They use chemicals to pass the messages, and these chemicals are critical in the regulation of processes such as fighting infections among others. 4. Cell Cycle and Regulation Cell division or the cycle of development of cells entails differences journeys that the cells undergo as they reproduce. It consists of four main phases: G1 Phase (Growth 1): S phase: The cell increases in size and studiously manufactures proteins that are required in DNA replication. S Phase (Synthesis): The process of set of chromosomes get duplicated so there are two similar sets of chromosomes present in the cell. G2 Phase (Growth 2): The cell itself keeps increasing in size and in preparing for division by mitosis. M Phase (Mitosis): The nucleus splits its chromosome and the cell body (nuclear fission and cytoplasm) to create two daughter cells. The cell cycle is extremely important in the normal growth and development of tissues and organs. This has the potential of causing uncontrolled growth of cells in our bodies such as those seen in cancer.