Question

Address the following (~200-300 words total):

1. How does a normal cell become a cancerous cell? What has to happen to it?
2. The video resources in the MasteringBio assignment focus on the telomerase enzyme role in cancer development. Explain the connection between telomerase activity and cancer.
3. The textbook essay focuses on a mutation that can happen in white blood cells that leads to blood cancer, leukemia. Explain the connection between BCR-ABL mutation and leukemia.
4. Propose a scenario where telomerase and BCR-ABL proteins are active in the same cell.

Answer 1

A healthy cells behaviour gradually changes, a result of damage to between three and seven of the hundreds of genes that control cell growth, division and life span. First, the cell starts to grow and multiply. Over time, more changes may take place. The cell and its descendants may eventually become immortal, escape destruction by the body's defences, develop their own blood supply and invade the rest of body.
Telomeres repetitive (TTAGGG) DNA–protein complexes at the ends of chromosomes, are crucial for the survival of cancer cells. They are maintained by an enzyme called telomerase in the vast majority of tumors telomeres protect chromosome ends from fusion and from being recognized as sites of DNA damage. There is mounting evidence for the existence of an important relationship between telomeres and telomerase and cellular aging and cancer. Normal human cells progressively lose telomeres with each cell division until a few short telomeres become uncapped leading to a growth arrest known as replicative aging .
The BCR-ABL gene shows up in patients with certain types of leukemia a cancer of the bone marrow and white blood cells. BCR-ABL is found in almost all patients with a type of leukemia called chronic myeloid leukemia (CML). Another name for CML is chronic myelogenous leukemia Both names refer to the same disease.
The telomerase protein is constitutively activated in malignant cells from many patients with cancer, including the chronic myeloid leukemia (CML), but whether telomerase is essential for the pathogenesis of this disease is not known.