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Name: Chatta
Status: student
Grade: 12+
Location: Outside U.S.
Country: India
Date: Winter 2011-2012


Question:
Does DNA change with growth or does it stay exactly the same throughout our life time?



Replies:
DNA generally does not change drastically over a lifetime. However, DNA expression can change over time based on developmental and/or environmental cues (even though the underlying sequences stay the same).

However, during cell division, minor mutations can always crop up. Some are silent while others are disastrous (i.e. cancer). To prevent the likelihood of such genomic disaster, cells are pre-programmed to senesce after a certain number of divisions. This is governed by the Hayflick Limit.

This is an extreme case, but there have been documented cases of viruses invading human cells and "exporting" some of their DNA through horizontal gene transfer. The HeLa cell line is one example of a chimeric "hybrid". These cells are cancerous, but highly useful for research because the Hayflick Limit does not apply. They are functionally immortal. br>
Dr. Tim Durham Undergraduate Studies & University Colloquium Department of Biological Sciences Florida Gulf Coast University



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