Sunday, January 30, 2011

DNA: The Blueprint for Life

My first nature observation is not an observation that takes place outdoors, but inside a lab. In genetics lab the other day, we isolated the DNA from beef liver. This was the first time I had ever extracted DNA, and it is a long, interesting process. It led me to think about how complex and amazingly powerful such a small molecule truly is. It took us over three hours to isolate the DNA using both centrifuging and substrates.
DNA, or deoxyribonucleic acid, is what encodes our genes that program our phenotypes, which are the physical reflections of our genotypes. This double-helical structure is so complex and long, and is compacted into the nucleus of every cell in our bodies. It is truly a fascinating thought. If stretched and unraveled to capacity, our human DNA in would be over 6ft in length inside every cell! The length of all of the DNA present inside one adult human, or the human genome, would be equivalent to nearly 70 trips from the earth to the sun and back! It is incredible that we carry all of this encoding information inside of us.
Although the human genome has been cracked, there are still endless questions about how genes are turned on and off, and how to exactly do so. I am personally curious in this field of genetics, known as epigenetics. Patterns of gene expression are governed by the cellular material — the epigenome — that sits on top of the genome. It is these epigenetic marks that tell your genes to switch on or off. It is through epigenetic marks that environmental factors like diet, stress and prenatal nutrition can make an imprint on genes that is passed from one generation to the next. Helping individuals not inherit transmissible diseases or avoid being more prone to obesity is a great application of this knowledge.  
Returning to my experience in the lab this past week, I found it interesting to examine the replication process of DNA. The DNA replicating process in eukaryotes is not as well understood as prokaryotes, since we are innately more complex organisms with linear DNA instead of circular; however, the process is still very similar. Therefore, I am providing any readers with this video on DNA replication to visualize the process, which involves an assortment of DNA enzymes (polymerases) and RNA (ribonucleic acid) enzymes, instead of simply reading about the process. Enjoy!

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