A domain is the highest taxonomic level of species in biology. In 1977, Woese and his coworkers developed the groundbreaking three-domain system.  They proposed this classification based on differences in the sequences of nucleotides in the cell’s ribosomal RNAs (known as 16S rRNA). They created the first worldwide tree of …

The genes of nuclear chromosome have a significant and key role in the inheritance of almost all traits from generations to generations,but altogether they cannot be considered as the sole vehicle of inheritance because certain experimental evidences suggest the occurance of certain extranuclear genes or DNA molecules in the cytoplasm …

In order to grow, cells have two options. They must either replicate themselves to create more cells, or the cells themselves must expand in volume. In humans, tissues such as the skin and blood contain cells that are actively dividing, while other tissues such as fat contain cells that expand. …