what are oncogenes ? give me detailed information !!!?

Question

dont want info frm wikipedia !!!!!!!!!

Answer 1

A cell can escape from its controls when a number of genes, whose products play a role in these regulatory processes, are changed by mutations in their DNA. A cell affected in this way will then, for instance, start to proliferate too fast or it will not die when appropriate. In both instances, the number of progeny of the transformed cell is higher than that of normal cells from the same tissue. Because the descendants of the transformed cell inherit the mutations, their behavior will be as much out of line as that of their progenitor. After 30 cell divisions the clone contains 1 billion cells and weighs 1 gm. Another 10 cell divisions and the tumor weighs 1 kg and contains 1000 billion cells. During this process it is possible that additional mutations occur in one of the transformed cells, which may then result in a subclone of cells with a more aggressive behavior. The speed with which a transformed cell may form a tumor depends on the nature of the cell in question and how much of the regulator processes still remain active.

The genes whose products play a regulator role in cell growth, division, differentiation and death are all potential cancer genes. Many of these genes have now been implicated in the pathogenesis of brain tumors. There are three different types of cancer genes:

Oncogenes
Tumor suppressor genes
Mutator genes

Oncogenes:

In the beginning of the 1980s the first human oncogenes were discovered and isolated. The RAS genes are the prototype of a large group of proto-oncogenes. The basic rule for all these genes is that they can be activated by specific changes (mutations) in their DNA. These mutations always result in a gain-of-function, which means that the protein product of the oncogene is somehow more active than the product of the proto-oncogene. Activation of a proto-oncogene can be brought about by point mutations as seen in the RAS genes but also by gene amplifications, which will result in an increase in the amount of the product of the gene or by chromosomal translocations which may activate gene expression, again resulting in the amount of the oncogenic protein. Other examples of activating mutations are the balanced chromosomal translocations that are often observed in leukemias and lymphomas and that lead to the fusion of two genes from different chromosomes, thus creating an entirely new gene with altered properties.

Answer 2

An oncogene is a modified gene, or a set of nucleotides that codes for a protein, that increases the malignancy of a tumor cell. Some oncogenes, usually involved in early stages of cancer development, increase the chance that a normal cell develops into a tumor cell, possibly resulting in cancer.

The first oncogene was discovered in 1970 and was termed SRC (pronounced SARK). Src was in fact first discovered as an oncogene in a chicken retrovirus. Experiments performed by Dr G. Steve Martin of the University of California, Berkeley demonstrated that the SRC was indeed the oncogene of the virus. In 1976 Drs. J. Michael Bishop and Harold E. Varmus of the University of California, San Francisco demonstrated that oncogenes were defective proto-oncogenes, found in many organisms including humans. For this discovery Bishop and Varmus were awarded the Nobel Prize in 1989.

Answer 3

Oncogenes are genes which promote cancer. A number of them have been identified in the last decade or so. The presence of oncogenes increases the chances that you will get certain cancers by a large percentage.

My mother had her second cancer last year. And, when the doctor found out that she and I had both had uterine cancer and that my sister had an early hysterectomy and so could have avoided cancer, he asked her to have a test for oncogenes. Luckily, it was negative. But this can be a very good test to get when indicated, because, if you know you have an oncogene, you can be especially careful and catch any cancer early when it is highly treatable.