He summarized his observations into three conclusions about cells:. We know today that the first two tenets are correct, but the third is clearly wrong. It became possible to maintain, grow, and manipulate cells outside of living organisms. The first continuous cell line to be so cultured was in by George Otto Gey and coworkers, derived from cervical cancer cells taken from Henrietta Lacks, who died from her cancer in The cell line, which was eventually referred to as HeLa cells , have been the watershed in studying cell biology in the way that the structure of DNA was the significant breakthrough of molecular biology.
In an avalanche of progress in the study of cells, the coming decade included the characterization of the minimal media requirements for cells and development of sterile cell culture techniques. It was also aided by the prior advances in electron microscopy, and later advances such as the development of transfection methods, the discovery of green fluorescent protein in jellyfish, and discovery of small interfering RNA siRNA , among others.
The study of the structure and function of cells continues today, in a branch of biology known as cytology. Advances in equipment, including cytology microscopes and reagents, have allowed this field to progress, particularly in the clinical setting. He saw bacteria some 9 years later. Pringsheim observed how a sperm cell penetrated an egg cell. Cambridge Instruments produced the first commercial scanning electron microscope.
It was unsurprising that van Leeuwenhoek would make such a discovery. He was a master microscope maker and perfected the design of the simple microscope which only had a single lens , enabling it to magnify an object by around two hundred to three hundred times its original size. Van Leeuwenhoek became fascinated. He went on to be the first to observe and describe spermatozoa in He even took a look at the plaque between his teeth under the microscope.
In a letter to the Royal Society, he wrote, "I then most always saw, with great wonder, that in the said matter there were many very little living animalcules, very prettily a-moving. In the nineteenth century, biologists began taking a closer look at both animal and plant tissues, perfecting cell theory. Scientists could readily tell that plants were completely made up of cells due to their cell wall. However, this was not so obvious for animal cells, which lack a cell wall.
German scientists Theodore Schwann and Mattias Schleiden studied cells of animals and plants respectively. These scientists identified key differences between the two cell types and put forth the idea that cells were the fundamental units of both plants and animals. However, Schwann and Schleiden misunderstood how cells grow. Eventually, other scientists began to uncover the truth.
Another piece of the cell theory puzzle was identified by Rudolf Virchow in , who stated that all cells are generated by existing cells.
At the turn of the century, attention began to shift toward cytogenetics, which aimed to link the study of cells to the study of genetics. In the s, Walter Sutton and Theodor Boveri were responsible for identifying the chromosome as the hub for heredity —forever linking genetics and cytology.
The discovery of the cell continued to impact science one hundred years later, with the discovery of stem cells, the undifferentiated cells that have yet to develop into more specialized cells.
Scientists began deriving embryonic stem cells from mice in the s, and in , James Thomson isolated human embryonic stem cells and developed cell lines. His work was then published in an article in the journal Science. It was later discovered that adult tissues, usually skin, could be reprogrammed into stem cells and then form other cell types. These cells are known as induced pluripotent stem cells. The discovery of the cell has had a far greater impact on science than Hooke could have ever dreamed in In addition to giving us a fundamental understanding of the building blocks of all living organisms, the discovery of the cell has led to advances in medical technology and treatment.
Today, scientists are working on personalized medicine, which would allow us to grow stem cells from our very own cells and then use them to understand disease processes. All of this and more grew from a single observation of the cell in a cork. Robert Hook refined the design of the compound microscope around and published a book titled Micrographia which illustrated his findings using the instrument. How do organelles benefit eukaryotic cells? Why is nucleus called the brain of the cell?
How does the nucleus differ in prokaryotic cells and eukaryotic cells? How are the nucleus and the nucleolus different? How do ribosomes relate to DNA?
How do ribosomes differ from lysosomes? Why is the Golgi Apparatus located where it is? What does the golgi apparatus do in a plant cell?
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