PATHOLOGY

Detailed explanation-1: -In order for a cell to differentiate into its specialized form and function, it need only manipulate those genes (and thus those proteins) that will be expressed, and not those that will remain silent. The primary mechanism by which genes are turned “on” or “off” is through transcription factors.

Detailed explanation-2: -Stem cells produce new cells by dividing. In the right conditions, these new cells can then continue to divide and differentiate into specialized cells. Stem cells can also divide to produce new stem cells to replace themselves. They are self-replicating.

Detailed explanation-3: -Signals from the environment-chemicals, extracellular proteins/hormones/factors, neighboring cells, the physical environment-converge on the cell, typically activating a signaling cascade that leads to gene expression. These specific proteins change the phenotype into that of a more specialized cell.

Detailed explanation-4: -Embryonic stem cells are the starter cells of the human body. They are undifferentiated, which means they have not matured and specialized, and they are able to become any other kind of cell in the body. In embryos, these cells multiply and differentiate to become organs, bones and muscles.

Detailed explanation-5: -The cell types in a multicellular organism become different from one another because they synthesize and accumulate different sets of RNA and protein molecules. They generally do this without altering the sequence of their DNA.