Lamarckism
The theory of acquired characteristics put forth by Jean-Baptiste P.A. Lamarck (1744-1829), a French botanist, zoologist and biological philosopher.
According to Lamarck, evolution occurs because organisms can inherit traits acquired by their ancestors. Giraffes can only survive by eating leaves high up on trees so they stretch their necks to reach the leaves and this stretching of the neck is passed on to later generations.
The basic tenet of Lamarckism has been rejected. Darwinism (the theory of the origin of species and the development of higher organisms from lower forms through natural selection, the survival of the fittest, and the evolution of humans from an ancestor common to himself and the apes) has prevailed, together with the principles of transmission genetics.
Lysenkoism was a 20th-century Soviet version of Lamarckism.
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Destruction. Hemolysis is the destruction of red blood cells with the release of hemoglobin; bacteriolysis is the destruction of bacteria; etc. Lysis can also refer to the subsidence of one or more symptoms of an acute disease as, for example, the lysis of fever in pneumonia.
- Lysosomal enzyme
An enzyme in an organelle (a little organ) called the lysosome within the cell. Lysosomal enzymes degrade (break down) macromolecules (large molecules) and other materials (such as bacteria) that have been taken up by the cell during the process of endocytosis. In endocytosis, macromolecules and particles from outside the cell are taken up by the […]
- Lysosome
An organelle (a little organ) in a cell containing enzymes that degrade macromolecules (large molecules) and other items (such as bacteria) taken up by a cell during the process of endocytosis. In endocytosis, macromolecules and particles outside the cell are taken up by the cell via a progressive invagination (inpouching) and eventual pinching off of […]
- Lytic
Suffix having to do with lysis (destruction), as in hemolytic anemia, the excessive destruction of red blood cells leading to anemia.
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A disorder of the heart’s electrical system that predisposes individuals to irregular heartbeats, fainting spells, and sudden death. The irregular heartbeats are typically brought on by stress or vigorous activity. Abbreviated LQTS. LQTS is often symptomless and undiagnosed, but it is well known as a cause of sudden cardiac death in young, apparently healthy people, […]