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An 1831 color lithograph by Robert Seymour depicts cholera as a robed, skeletal creature emanating a deadly black cloud.. The miasma theory (also called the miasmic theory) is an abandoned medical theory that held that diseases—such as cholera, chlamydia, or the Black Death—were caused by a miasma (μίασμα, Ancient Greek for 'pollution'), a noxious form of "bad air", also known as ...
Galvanic cell with no cation flow. A galvanic cell or voltaic cell, named after the scientists Luigi Galvani and Alessandro Volta, respectively, is an electrochemical cell in which an electric current is generated from spontaneous oxidation–reduction reactions.
The theory of classical irreversible thermodynamics treats self-assembly under a generalized chemical potential within the framework of dissipative systems. [ 147 ] [ 148 ] [ 149 ] The second law of thermodynamics requires that overall entropy increases, yet life is distinguished by its great degree of organization.
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.
Each cell type is defined by its particular pattern of regulated gene expression. Cell differentiation is thus a transition of a cell from one cell type to another and it involves a switch from one pattern of gene expression to another. Cellular differentiation during development can be understood as the result of a gene regulatory network.
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. [1] [2] All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. [3] Cell biology is the study of the structural and functional ...
Autophagy was first observed by Keith R. Porter and his student Thomas Ashford at the Rockefeller Institute.In January 1962 they reported an increased number of lysosomes in rat liver cells after the addition of glucagon, and that some displaced lysosomes towards the centre of the cell contained other cell organelles such as mitochondria.
In it Burnet expanded the ideas of Talmage and named the resulting theory the "clonal selection theory". He further formalised the theory in his 1959 book The Clonal Selection Theory of Acquired Immunity. He explained immunological memory as the cloning of two types of lymphocyte. One clone acts immediately to combat infection whilst the other ...