The following points highlight the six main types of genes. The types are: 1. Complementary Genes 2. Duplicate Genes 3. Polymeric Genes 4. Modifying Genes 5. Lethal Genes 6. Moveable Genes. Type # 1. Complementary Genes: Bateson and Punnett crossed two different white flowered varieties of sweet pea and obtained an F1 progeny of red flowered plants. On self-pollination the [...]
The work of J. Cairns demonstrated DNA replication in bacteria in an elegant way. He used high resolution autoradiography for observing the distribution of radioactive label in the "chromosomes" of dividing E. coli cells. The bacterial cells were grown on a medium containing tritiated thymidine. The labelled DNA was extracted from the cells and spread on EM grids. A very [...]
The following points highlight the four main factors that influence the life of an organism. The factors are: 1. Temperature 2. Water 3. Light 4. Soil. Factor # 1. Temperature: It is the most ecologically significant environ mental factor. It varies seasonally. Thus, decreases progressively from the equator towards the poles and from plains to the mountain tops. It ranges [...]