(DOWNLOAD) "Crazy Genes (Biology TODAY)" by The American Biology Teacher # eBook PDF Kindle ePub Free
eBook details
- Title: Crazy Genes (Biology TODAY)
- Author : The American Biology Teacher
- Release Date : January 01, 2010
- Genre: Life Sciences,Books,Science & Nature,
- Pages : * pages
- Size : 159 KB
Description
Things seem to have gotten rather crazy in the world of genetics. Even the concept of the gene is being questioned. The gene - what could be more solid than that? But think about it: the definition of a gene has changed in a number of ways since it was introduced by Wilhem Johannsen in 1919 as an abbreviation for the term "pangen," which had been coined by Hugo de Vries 20 years earlier to describe the unit that controls the production of a single hereditary trait. After all, neither man knew that DNA was the material substance of such units. And it wasn't until the structure of DNA was discovered and explored in the mid-20th century that the idea of a gene as a sequence of nucleotides developed, along with the concept that the sequence was transcribed into mRNA and then translated into a protein sequence. Also, keep in mind that the idea of a gene was further elaborated with the discovery that only portions of the mRNA (exons) were actually translated. So genes have had quite a checkered career already, and it shouldn't come as a big surprise that the gene concept is being renovated yet again. We humans need to find names for things even when we know very little about them, so the idea of hereditary elements was given a designation based on little real knowledge of what genes actually were. And our knowledge is still partial. The reason the gene's definition has been called into question lately is because of the rush of genomic data appearing in the last few years. Since we are again tempted to think we have the story straight, we think it's time for a definitional overhaul. The first inkling that this would be needed was when the human genome was published and the gene number was estimated to be around 25,000, meaning that most of the genome didn't seem to be coding for protein. If most DNA wasn't made up of genes, what was it doing, if anything? This question hasn't come close to being answered yet. What working out the human genome, and that of dozens of other species, has indicated is that knowing the sequence of nucleotides is not enough to figure out how genes are really behaving.