The sequencing of the human genome, which is finding the order of the more than 3 billion nucleotides (A, T, C, and G) in the human chromosomes, is being accomplished by two independent groups of scientists. The two versions of this sequence were published in the magazines Nature and Science in February 2001. One group, formerly led by Craig Venter, is Celera Genomics, of Rockville, Maryland, a company started in 1998. The other research group is the result of a consortium of public agencies with laboratories in several countries.
The sequence of the human genome carried out by the public sector, now led by Francis Collins, has a budget of more than $3 billion. The major sponsors were the U.S. Department of Energy and the National Institutes of Health (NIH), as well as the Wellcome Foundation of England. The current map covers about 95 percent of the human genome and has been found to be 99.96 percent accurate. This work has revealed, in a surprising way, that the human genome only has about 30,000 genes instead of 70,000 to 140,000, according to previous estimates. With a DNA sequence of over 3 billion base pairs (bp) and considering the average gene size of 3,000 bp, it is estimated that only 3 percent of the human genome actually codes for some protein. This means that about 97 percent of the human genome has seemingly no coding function; that is, most of the nucleotide sequences in human DNA do not code for genes. This nonfunctional portion of DNA has, for lack of a more accurate term, been called "junk DNA," and its function and purpose have yet to be understood. More important, the data from the Human Genome Project has also revealed that each human being, independent of apparent differences, is about 99.9 percent identical to any other person.
With so much interest and emphasis on the Human Genome Project, what are the practical applications of the sequence of the human genome? The information will help in the early diagnosis of disease, an understanding of the predisposition to genetic diseases, and in genetic counseling, for example. For instance, the sequence of the human genome allows geneticists to understand why certain people have a predisposition to heart disease, and it will eventually lead to the development of new drugs specifically developed to combat the cause of disease and not the symptoms alone. Sequencing the genome will make available basic scientific knowledge for the development of gene therapies for incurable diseases, such as diabetes, muscular dystrophy, cystic fibrosis, Parkinson's disease, and Alzheimer's disease.
By the beginning of 2002, geneticists had already isolated about 13,000 human genes and learned about their functions, including those that code for eye color, circulatory proteins, and genes that when mutated cause a predisposition for developing breast cancer and prostate cancer. All this complex information is contained in each and every cell of the human body. If it were possible to stretch out the incredible amount of information contained in the DNA of all the chromosomes in a single human cell, it would reach about seven feet. If the DNA of all the cells of the human body were stretched out and aligned, it would be enough to cover the distance from Earth to the moon about 8,000 times. Incredible packaging mechanisms allow this information to be stored within each tiny cell.
Tags: Bio Technology, Bio Genetics, Genetic Engineering
0 comments:
Post a Comment