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Cancer, Aging and Telomeres

Cancer, Aging and Telomeres. How molecular genetic research contributes to a better understanding of cancer and aging in humans. What is cancer?. Cancer is the result of accelerated growth of undifferentiated cells Proto-oncogenes in cells regulate mitosis, cell growth and apoptosis

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Cancer, Aging and Telomeres

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  1. Cancer, Aging and Telomeres How molecular genetic research contributes to a better understanding of cancer and aging in humans

  2. What is cancer? • Cancer is the result of accelerated growth of undifferentiated cells • Proto-oncogenes in cells regulate mitosis, cell growth and apoptosis • Apoptosis – cells are programmed to self destruct once they become damaged or old • Oncogenes are mutated proto-oncogenes that cause uncontrolled growth and result in tumors

  3. Normal Cell Growth • Mitosis is tightly controlled by enzymes and feedback mechanisms • Membrane proteins signal contact – this “contact inhibition” halts cell division (growth and replication)

  4. Proto - oncogenes to oncogenes • Cells also have proteins that recognize cells from the wrong part of the body and destroy them (apoptosis) • Cells that are damaged self destruct (apoptosis) • Mutations in any protooncogenes can result in oncogenes that do not initiate apoptosis

  5. Epidermal Growth Factor Receptor • Example: Epidermal Growth Factor Receptor • Normally, a molecule activates the receptor and the cell begins mitosis • A mutation in the ECF receptor that no longer requires an activator, means that cell continues to divide indefinitely

  6. The Immortal cells of Henrietta Lacks • Henrietta Lacks' cells were essential in developing the polio vaccine and were used in scientific landmarks such as cloning, gene mapping and in vitro fertilization. Courtesy of the Lacks family • Read more: http://www.smithsonianmag.com/science-nature/Henrietta-Lacks-Immortal-Cells.html#ixzz1LDFqjFDb

  7. HeLa Cells • Henrietta Lack’s cells were taken from a biopsy sample of a cervical cancer tumor in 1951 • They were used to develop an immortal line of human cells, that could divide indefinitely, be split into batches and given to different researchers • All vaccine development and many drug tests can only be done on human tissue cultures • Read more in The Immortal Life of Henrietta Lacks by Rebecca Skloot

  8. Telomeres • Telomeres are made of short subunits that extend the length of a chromosome • DNA polymerase can not replicate and entire chromosome – some information at the end is lost as the enzyme detaches • TTAGGG that repeats about 2 000 times in human skin cells is an example of a telomere • They are found at the end of linear chromosomes • Telomerase is an enzyme that adds telomeres

  9. Telomeres and Protoists • Single celled eukaryotes contain large amounts of telomerase that add telomeric sequences after DNA cell division • This makes them immortal – like this amoeba

  10. Telomerase • Adult stem cells in bone marrow that produce blood cells contain telomerase so there is no limit to their cell divisions • Telomerase has also been found in certain cancerous tumors and has been shown to induce tumors when introduced into healthy tissue • Shortening telomeres eventually leads to DNA polymerases clipping off the ends of genes during replication and is thought to contribute to aging

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