Question

Define Germ Plasm theory.

Answer 1

Hint: The relevant idea that information cannot permit from somatic cells to the germline, difficult to Lamarckism, is called the Weismann barrier. The theory to some extent anticipated the development of modern genetics.

Complete Answer:
- Germplasm (German: Keimplasma) is a biological concept assembled in the 19th century by the German biologist August Weismann. It states that heritable information is carried only by germ cells in the gonads (ovaries and testes), not by somatic cells.
- According to his theory, germplasm, which is unrelated to all other cells of the body (somatoplasm), is the important element of germ cells (eggs and sperm) and is the genetic material that is passed from generation to generation. Weismann first nominated this theory in 1883; it was later distributed in his treatise Das Keimplasma (1892;
- The Germ-Plasm: A Theory of Heredity). This view contradicted Lamarck’s theory of obtained characteristics, which was a dominant theory of heredity of the time. Although the circumstances of the germ-plasm theory have been adapted, its premise of the continuity of hereditary material is the justification of the modern understanding of the method of physical inheritance.
- This theory is based on the theory that living bodies are established of two fundamentally differ­ent types of material-the germplasm (protoplasm of germ cells such as sperms and ova) and the somatoplasm (protoplasm of somatic or body cells). The germplasm is accountable for the development of reproductive parts and remains in the organism, sealed and secluded from the somatoplasm which assembles out of the germplasm.
- In course of the period, the germplasm gives growth to the offspring in which again the germplasm remains distinct from the somatoplasm that it develops. Thus, the germplasm is a consecutive stream from generation to generation while the somatoplasm is formed new at every generation and is discontinuous. In bisexual plants and animals, at every family, the germplasm commotion becomes an intersection of the maternal and the paternal streams.

Note:
1. The idea of continuity and immortality of germplasm assembled the ground for the continuity of chromosome or DNA from one generation to the next.
2. It created the ground for the understanding of the concept of particulate inheritance of Mendel.
3. It provides some evidence about genes (determinants) which reside in chromosomes and represent some part of the animal body.
4. The considerable donation of this theory, according to the embryologists, is that it recommends the division of germplasm and somatoplasm during the separation of the zygote during embryogenesis.