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Loin

The portion of the lower back from just below the ribs to the pelvis.

Loneliness, fear of

“autos” (self) and “phobos” (fear). “Autos” has given us many English words such as “automatic” and “automotive” (self-moving) and “autonomy” (self-governing). And “phobos” has bequeathed us a vast number of phobias such as “claustrophobia” (fear of closed places) and “acrophobia” (fear of heights).

Long arm of a chromosome

The long arm of a chromosome is termed the q arm. All human chromosomes have 2 arms, the p (short) arm and the q (long) arm. They are separated from each other only by a primary constriction, the centromere, the point at which the chromosome is attached to the spindle during cell division. The symbol […]

Long QT syndrome

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, […]

Lytic

Suffix having to do with lysis (destruction), as in hemolytic anemia, the excessive destruction of red blood cells leading to anemia.

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 […]

Lysis

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 […]

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 […]

Lysenkoism

A theory put forth by a Russian plant-breeder named Trofim Denisovich Lysenko [1898-1976] during the Lenin/Stalin years that served to stifle the progress of genetics in the Soviet Union. Lysenko rejected Mendelian genetics in favor of the doctrine of acquired characteristics, a form of Lamarckism. (According to the earlier doctrine of Lamarck, evolution occurs because […]