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The same cells that recognize PAMPs on microbial pathogens may bind to the antigen of a foreign blood cell and recognize it as a pathogen because the antigen is unfamiliar. [11] It is not easy to classify red blood cell recognition as intrinsic or extrinsic, as a foreign cell may be recognized as part of the organism if it has the right antigens.
The grandmother cell hypothesis is an extreme version of the idea of sparseness, [22] [5] and is not without critics. The opposite of the grandmother cell theory is the distributed representation theory, that states that a specific stimulus is coded by its unique pattern of activity over a large group of neurons widely distributed in the brain.
In biology, cell signaling (cell signalling in British English) is the process by which a cell interacts with itself, other cells, and the environment. Cell signaling is a fundamental property of all cellular life in prokaryotes and eukaryotes. Typically, the signaling process involves three components: the signal, the receptor, and the effector.
In immunology, clonal selection theory explains the functions of cells of the immune system (lymphocytes) in response to specific antigens invading the body. The concept was introduced by Australian doctor Frank Macfarlane Burnet in 1957, in an attempt to explain the great diversity of antibodies formed during initiation of the immune response .
The recognition-by-components theory, or RBC theory, [1] is a process proposed by Irving Biederman in 1987 to explain object recognition. According to RBC theory, we are able to recognize objects by separating them into geons (the object's main component parts). Biederman suggested that geons are based on basic 3-dimensional shapes (cylinders ...
In biology, cell theory is a scientific theory first formulated in the mid-nineteenth century, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells.
Nerve cells are connected by sites of contact and not cytoplasmic continuity. Waldeyer himself was neutral on this point, and strictly speaking the neuron doctrine does not depend upon this element. The heart is an example of excitable tissue where the cells connect via cytoplasmic continuity and yet is perfectly consistent with cell theory.
The cell on the left is going through mitosis and its chromosomes have condensed. Cell nucleus: A cell's information center, the cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It houses the cell's chromosomes, and is the place where almost all DNA replication and RNA synthesis (transcription) occur.