Answer:
Explanation:
Mutations are effectively errors in the DNA copying or transcription processes. They can occur naturally or be caused by mutagens, either chemical such as benzene or environmental such as ultraviolet light. These mutations concern the basses on DNA and can be as small as one base changing to another or as complex and detrimental as the insertion of a new base along the strand. Such mutations can drastically change the proteins created by an organism and affect entire chromosomes or genes. Some mutations that affect gametes can be passed down from parent to offspring and are called germline mutations. Such mutations can create entirely new alleles and increase a populations genetic variation. One such genetic mutation that occurs in humans in cancer. Cancers are errors in a cells DNA caused by mutations that allow the cell to grow and multiply uncontrollably copying the mutated DNA along the way. One specific type of cancer is breast cancer. Breast cancer has two different types of mutations. There are the BRCA 1 and 2 varieties. According to the charts, the BRCA 1 mutation appears to be more deadly. If a woman carries the BRCA 1 mutation, she has, once again according to the chart, an 18 percent chance of death. All of the women in the table above had a family history of cancer. This would point to the fact that cancer can be passed down as well as contracted from a certain type of mutagen known as a carcinogen. The table also references preventative surgeries in a number of women carrying both the BRCA 1 and 2 mutations as well as some without either. Unfortunately, given the data shown, it is impossible to determine the effectiveness of such procedures. To be able to judge this, data about the survival rates of women who underwent the procedures versus those who did not would be required. The bar graph above the chart also mentions ages. It shows that the numbers of cases of breast cancer increase rather quickly until ages 50-59 and then steadily and slowly decline. Most breast cancer cases occur in women 50-59 years old. This tells us that the mutation takes quite a few years to manifest as it is a genetic mutation and is furthered by the sufferers decreased ability to fight off carcinogens with age. If cancer can be removed by surgeries or by the death of the afflicted, why does it still exist in our population? The answer is simple. Cancer can be passed on hereditarily but that is not the only way for it to be contracted. Carcinogens that exist as chemicals or as environmental factors are present everywhere and can mutate one’s DNA and therefore genes. This can then be passed on to offspring as well.
