I need help for the following questions. Thanks!!!
1. What are growth factors? Explain how they function to control cell division and differentiation.
A growth factor is a naturally occuring substanc capable of stimulating cellular growth, proliferation and differentiation. Usually it is a protein or a steroid hormone. Growth factors are important for regulating a variety of cellular processes.
Growth factores typically act as signaling molecules between cells. Examples are cytokines and hormones that bind to specific receptor on the surfact of their target cells.
They often promote cell differentation and mutaration, which varies between growth factore. For example, bone morphogenic proteins stimulate bone cell differentiation, whil fibroblast growth factors and vascular endothlial growth factors stimulate blood vessel differentiation (angiogenesis).
2. What are proto-oncogenes? What do they do? What happens when proto-oncogenes become oncogenes?
A proto-oncogene is a normal gene that have many different functions in the cell. Some proto-oncogenes provide signales that read ti cell division. Other proto-oncogenes regulate progranned cell death (apoptosis). Apoptosis leads to the elimination of cells without releasing harmful substances into the surrounding area. Apoptosis plays a crucial role in developing and maintaining health by eliminating old cells, unnecessary cells, and unhealth cells. When a proto-oncogene becomes mutilated it becomes a oncogene. This causes the cell to devide in an unregulated manner. An oncogene may contribute to the growth of a tumor, which may be cancerous.
3. What is the function of a tumor-suppressor gene?
Tumor-suppressor genes regulate and stop cell division.
An example is P53 which causes cells with DNA damage to undergo programmed cell death (apoptosis). This prevents them forming tumor.