Cells were first seen in 17th-centuryEurope with the invention of thecompound microscope. In 1665,Robert Hooke referred to the building blocks of all living organisms as "cells" (published inMicrographia) after looking at a piece ofcork and observing a structure reminiscent ofmonastic cells;[4][5] however, the cells were dead. They gave no indication to the actual overall components of a cell. A few years later, in 1674,Anton Van Leeuwenhoek was the first to analyze live cells in his examination ofalgae. Many years later, in 1831,Robert Brown discovered thenucleus. All of this preceded thecell theory which states that all living things are made up of cells and that cells are organisms' functional and structural units. This was ultimately concluded by plant scientistMatthias Schleiden[5] and animal scientistTheodor Schwann in 1838, who viewed live cells in plant and animal tissue, respectively.[3] 19 years later,Rudolf Virchow further contributed to the cell theory, adding that all cells come from the division of pre-existing cells.[3]Viruses are not considered in cell biology – they lack the characteristics of a living cell and instead are studied in themicrobiology subclass ofvirology.[6]
Cell biology research looks at different ways to culture and manipulate cells outside of a living body to further research inhuman anatomy andphysiology, and to derive medications. The techniques by which cells are studied have evolved. Due to advancements in microscopy, techniques and technology have allowed scientists to hold a better understanding of the structure and function of cells. Many techniques commonly used to study cell biology are listed below:[7]
Cell culture: Utilizes rapidly growing cells on media which allows for a large amount of a specific cell type and an efficient way to study cells.[8] Cell culture is one of the major tools used in cellular and molecular biology, providing excellent model systems for studying the normal physiology and biochemistry of cells (e.g., metabolic studies, aging), the effects of drugs and toxic compounds on the cells, and mutagenesis and carcinogenesis. It is also used in drug screening and development, and large scale manufacturing of biological compounds (e.g., vaccines, therapeutic proteins).
Fluorescence microscopy: Fluorescent markers such asGFP, are used to label a specific component of the cell. Afterwards, a certain light wavelength is used to excite the fluorescent marker which can then be visualized.[8]
Phase-contrast microscopy: Uses the optical aspect of light to represent the solid, liquid, and gas-phase changes as brightness differences.[8]
Confocal microscopy: Combines fluorescence microscopy with imaging by focusing light and snap shooting instances to form a 3-D image.[8]
Transmission electron microscopy: Involves metal staining and the passing of electrons through the cells, which will be deflected upon interaction with metal. This ultimately forms an image of the components being studied.[8]
Cytometry: The cells are placed in the machine which uses a beam to scatter the cells based on different aspects and can therefore separate them based on size and content. Cells may also be tagged with GFP-fluorescence and can be separated that way as well.[9]
Cell fractionation: This process requires breaking up the cell using high temperature or sonification followed bycentrifugation to separate the parts of the cell allowing for them to be studied separately.[8]
The scientific branch that studies and diagnoses diseases on the cellular level is calledcytopathology. Cytopathology is generally used on samples of free cells or tissue fragments, in contrast to thepathology branch ofhistopathology, which studies whole tissues. Cytopathology is commonly used to investigate diseases involving a wide range of body sites, often to aid in the diagnosis of cancer but also in the diagnosis of some infectious diseases and other inflammatory conditions. For example, a common application of cytopathology is thePap smear, ascreening test used to detectcervical cancer, andprecancerous cervical lesions that may lead to cervical cancer.[10]
^Alberts, Bruce; Johnson, Alexander D.; Morgan, David; Raff, Martin; Roberts, Keith; Walter, Peter (2015). "Cells and genomes".Molecular Biology of the Cell (6th ed.). New York, NY: Garland Science. pp. 1–42.ISBN978-0815344322.
._Natuurkundige_te_Delft_Rijksmuseum_SK-A-957.jpeg)
.jpg)
