What is junk DNA, and what is it worth?

Answer 1

Our genetic blueprint consists of 3.42 billion nucleotides packaged in 23 pairs of linear chromosomes. Most mammalian genomes are of comparable size—the mouse script is 3.45 billion nucleotides, the rat's is 2.90 billion, the cow's is 3.65 billion—and code for a similar number of genes: about 35,000. Of course, extremes exist: the bent-winged bat (Miniopterus schreibersi) has a relatively small 1.69-billion-nucleotide genome; the red viscacha rat (Tympanoctomys barrerae) has a genome that is 8.21 billion nucleotides long. Among vertebrates, the highest variability in genome size exists in fish: the green puffer fish (Chelonodon fluviatilis) genome contains only 0.34 billion nucleotides, while the marbled lungfish (Protopterus aethiopicus) genome is gigantic, with almost 130 billion. Interestingly, all animals have a large excess of DNA that does not code for the proteins used to build bodies and catalyze chemical reactions within cells. In humans, for example, only about 2 percent of DNA actually codes for proteins.

For decades, scientists were puzzled by this phenomenon. With no obvious function, the noncoding portion of a genome was declared useless or sometimes called "selfish DNA," existing only for itself without contributing to an organism's fitness. In 1972 the late geneticist Susumu Ohno coined the term "junk DNA" to describe all noncoding sections of a genome, most of which consist of repeated segments scattered randomly throughout the genome.
Typically these sections of junk DNA come about through transposition, or movement of sections of DNA to different positions in the genome. As a result, most of these regions contain multiple copies of transposons, which are sequences that literally copy or cut themselves out of one part of the genome and reinsert themselves somewhere else.

Elements that use copying mechanisms to move around the genome increase the amount of genetic material. In the case of "cut and paste" elements, the process is slower and more complicated, and involves DNA repair machinery. Nevertheless, if transposon activity happens in cells that give rise to either eggs or sperm, these genes have a good chance of integrating into a population and increasing the size of the host genome.


Although very catchy, the term "junk DNA" repelled mainstream researchers from studying noncoding genetic material for many years. After all, who would like to dig through genomic garbage? Thankfully, though, there are some clochards who, at the risk of being ridiculed, explore unpopular territories. And it is because of them that in the early 1990s, the view of junk DNA, especially repetitive elements, began to change. In fact, more and more biologists now regard repetitive elements as genomic treasures. It appears that these transposable elements are not useless DNA. Instead, they interact with the surrounding genomic environment and increase the ability of the organism to evolve by serving as hot spots for genetic recombination and by providing new and important signals for regulating gene expression.
Genomes are dynamic entities: new functional elements appear and old ones become extinct. And so, junk DNA can evolve into functional DNA. The late evolutionary biologist Stephen Jay Gould and paleontologist Elisabeth Vrba, now at Yale University, employed the term "exaptation" to explain how different genomic entities may take on new roles regardless of their original function—even if they originally served no purpose at all. With the wealth of genomic sequence information at our disposal, we are slowly uncovering the importance of non-protein-coding DNA.

In fact, new genomic elements are being discovered even in the human genome, five years after the deciphering of the full sequence. Last summer developmental biologist Gill Bejerano, then a postdoctoral fellow at the University of California, Santa Cruz, and now a professor at Stanford University, and his colleagues discovered that during vertebrate evolution, a novel retroposon—a DNA fragment, reverse-transcribed from RNA, that can insert itself anywhere in the genome—was exapted as an enhancer, a signal that increases a gene's transcription. On the other hand, anonymous sequences that are nonfunctional in one species may, in another organism, become an exon—a section of DNA that is eventually transcribed to messenger RNA. Izabela Makalowska of Pennsylvania State University recently showed that this mechanism quite often leads to another interesting feature in the vertebrate genomes, namely overlapping genes—that is, genes that share some of their nucleotides..

Answer 2

Junk DNA in non-coding DNA. It is not transcribed or even if transcribed, the RNA short lived.
Junk DNA is not totally useless.It has certain functions. Had there been no function natural selection would not have favoured it kept it.To retain this DNA which accounts for more than the coding DNA, means it has some role in the cell.
1.It regulates the function of genes.
2.It is supposed to be ancient genes that have become useless by becoming converted into pseudogenes.
3.It could be introns and retrotransposons.
4 It acts as the umbrella for trapping mutations and environmental radiations.
5. It might be developed into future genes.

Answer 3

Junk DNA is a term for all that DNA that does not correspond to any coding, be it a protein, promotor region, methylated signal, yata yata yata. However, it does play an important role in our system. Not only can junk DNA one day become interpretable DNA, but it also serves as a protection fom pathogens, such as viruses. When a Virus infects our cells its DNA (or RNA)actually gets incorporated into our DNA. Now if that DNA infected a region that controlled your heart beat, that would be a serious problem. This junk DNA serves as a protection by limiting the chance of an infection that would do harm like that.

Answer 4

Junk DNA is important to people like population geneticists who look at differences within that "junk DNA" and within coding regions to determine genetic diversity. There are inter-simple sequence repeats, restriction enzyme length polymorphisms, and microsatellites (also known as variable nucleotide tandem repeats), repeats of nucleotide motifs. These are just to point out a few. These may or may not be in coding DNA and are great for population studies when litlle or none is known about the organism's genome.

Answer 5

All canines come from a single ancestor. So each 'organic blood' canines is in hassle-free terms a heavily inbred canines picking for specific features. Oversimplification, however the element is that canines proportion an undesirable lot of genetics. those tests , while provided acurately do what they say. They try for specific genetic markers linked with specific breeds. They then use a statstical formulation to count variety those markers and arrive at their result. a lot can flow incorrect. The pattern could be of undesirable high quality. achievable teh proprietor did it incorrect, or the lab used low priced ingredients. The try could be contaminated or accomplished incorrect. in the event that they seem to be a 'actual' or qualified lab, usually the tests would be superb. yet i could desire to set this up in my storage legally and that could desire to be suspect. there are countless agencies that in the time of hassle-free terms try for some markers, at an analogous time as others try for all. you'll be able to desire to renowned which variety of try. be sure you grant a high quality pattern and that they use sturdy technique. interior the top, it continues to be a guesstimate and not absolute. yet I even have seen lots of those tests be somewhat precise. and a few way off. So that's a youthful technologies that gets greater advantageous in time.

Answer 6

DNA is genetic material which carry hereditary characters from 1 generation to another it is useful in identification of children and there parents.

Answer 7

its not coding 4 any thing but it is there just to compensate the DNA length
eubzz is correct

Answer 8

No idea Sir