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Alexander Carl Heinrich Braun (10 May 1805 – 29 March 1877) was a German botanist from Regensburg, Bavaria.His research centered on the morphology of plants and was a very influential teacher who worked as a professor of botany at the universities of Freiburg, Giessen, and Berlin at various times.
The cell was first discovered by Robert Hooke in 1665 using a microscope. The first cell theory is credited to the work of Theodor Schwann and Matthias Jakob Schleiden in the 1830s. In this theory the internal contents of cells were called protoplasm and described as a jelly-like
Sidney Walter Fox (24 March 1912 – 10 August 1998) was a Los Angeles-born biochemist responsible for discoveries on the origins of biological systems. Fox explored the synthesis of amino acids from inorganic molecules, the synthesis of proteinous amino acids and amino acid polymers called "proteinoids" from inorganic molecules and thermal energy, and created what he thought was the world's ...
The typical normal human fetal cell will divide between 50 and 70 times before experiencing senescence. As the cell divides, the telomeres on the ends of chromosomes shorten. The Hayflick limit is the limit on cell replication imposed by the shortening of telomeres with each division. This end stage is known as cellular senescence.
The centrosome was discovered jointly by Walther Flemming in 1875 [1] [2] and Edouard Van Beneden in 1876. [3] [4] Flemming investigated the process of cell division and the distribution of chromosomes to the daughter nuclei, a process he called mitosis from the Greek word for thread. However, he did not see the splitting into identical halves ...
The cells were filtered, and since centrifuges were not available at the time, the cells were allowed to settle to the bottom of a beaker. He then tried to isolate the nuclei free of cytoplasm . Miescher subjected the purified nuclei to an alkaline extraction followed by acidification, resulting in the formation of a precipitate that he called ...
Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested materials. Endocytosis includes pinocytosis (cell drinking) and phagocytosis (cell eating). It is a form of ...
Hayflick was born May 20, 1928, in Philadelphia, Pennsylvania.He received his Ph.D. at the University of Pennsylvania in 1956. After receiving a post-doctoral fellowship for study at the University of Texas Medical Branch in Galveston under the tutelage of the renowned cell culturist Charles M. Pomerat (1905–1964), [8] he returned to Philadelphia, where he spent ten years as an Associate ...