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The Hayflick limit, or Hayflick phenomenon, is the number of times a normal somatic, differentiated human cell population will divide before cell division stops. [ 1 ] [ 2 ] The concept of the Hayflick limit was advanced by American anatomist Leonard Hayflick in 1961, [ 3 ] at the Wistar Institute in Philadelphia , Pennsylvania.
Cell growth refers to an increase in the total mass of a cell, including both cytoplasmic, nuclear and organelle volume. [1] Cell growth occurs when the overall rate of cellular biosynthesis (production of biomolecules or anabolism) is greater than the overall rate of cellular degradation (the destruction of biomolecules via the proteasome, lysosome or autophagy, or catabolism).
The Limits to Growth (LTG) is a 1972 report [2] that discussed the possibility of exponential economic and population growth with finite supply of resources, studied by computer simulation. [3] The study used the World3 computer model to simulate the consequence of interactions between the Earth and human systems.
Liebig's law has been extended to biological populations (and is commonly used in ecosystem modelling).For example, the growth of an organism such as a plant may be dependent on a number of different factors, such as sunlight or mineral nutrients (e.g., nitrate or phosphate).
These stress factors include both environmental and internal damaging events, abnormal cellular growth, oxidative stress, autophagy factors, among many other things. [ 8 ] The physiological importance for cell senescence has been attributed to prevention of carcinogenesis , and more recently, aging, development, and tissue repair. [ 9 ]
Cell division can occur without cell growth, producing many progressively smaller cells (as in cleavage of the zygote), while cell growth can occur without cell division to produce a single larger cell (as in growth of neurons). Thus, cell proliferation is not synonymous with either cell growth or cell division, despite these terms sometimes ...
Alex Jones’ control of Infowars has lived on another day, although the long-term future of the site, known for peddling conspiracy theories, has been thrown into doubt after a bankruptcy judge ...
The Allee effect is a phenomenon in biology characterized by a correlation between population size or density and the mean individual fitness (often measured as per capita population growth rate) of a population or species.