DNA is perhaps the most famous biological molecule; it is present in all forms of life on earth. But what is DNA or deoxyribonucleic acid?
Here, we cover the essentials. Virtually every cell in your body contains DNA or the genetic code that makes you you. DNA carries the instructions for the development, growth, reproduction, and functioning of all life. Differences in the genetic code are the reason why one person has blue eyes rather than brown, why some people are susceptible to certain diseases, why birds only have two wings, and why giraffes have long necks. Amazingly, if all of the DNA in the human body was unraveled, it would reach to the sun and back more than times.
It holds the instructions for building the proteins that are essential for our bodies to function. DNA is a two-stranded molecule that appears twisted, giving it a unique shape referred to as the double helix. Each of the two strands is a long sequence of nucleotides or individual units made of:. The bases of the two strands of DNA are stuck together to create a ladder-like shape. Most DNA lives in the nuclei of cells and some is found in mitochondria, which are the powerhouses of the cells.
Because we have so much DNA 2 meters in each cell and our nuclei are so small, DNA has to be packaged incredibly neatly. Strands of DNA are looped, coiled and wrapped around proteins called histones. In this coiled state, it is called chromatin. Animals Wild Cities Wild parakeets have taken a liking to London Love them or hate them, there's no denying their growing numbers have added an explosion of color to the city's streets.
India bets its energy future on solar—in ways both small and big. Environment Planet Possible India bets its energy future on solar—in ways both small and big Grassroots efforts are bringing solar panels to rural villages without electricity, while massive solar arrays are being built across the country.
Epic floods leave South Sudanese to face disease and starvation. Travel 5 pandemic tech innovations that will change travel forever These digital innovations will make your next trip safer and more efficient.
But will they invade your privacy? Go Further. Animals Wild Cities This wild African cat has adapted to life in a big city. Animals This frog mysteriously re-evolved a full set of teeth. Animals Wild Cities Wild parakeets have taken a liking to London. Animals Wild Cities Morocco has 3 million stray dogs. Meet the people trying to help. Animals Whales eat three times more than previously thought. Environment Planet Possible India bets its energy future on solar—in ways both small and big.
Environment As the EU targets emissions cuts, this country has a coal problem. Paid Content How Hong Kong protects its sea sanctuaries. To understand DNA's double helix from a chemical standpoint, picture the sides of the ladder as strands of alternating sugar and phosphate groups - strands that run in opposite directions. Each "rung" of the ladder is made up of two nitrogen bases, paired together by hydrogen bonds.
Because of the highly specific nature of this type of chemical pairing, base A always pairs with base T, and likewise C with G. So, if you know the sequence of the bases on one strand of a DNA double helix, it is a simple matter to figure out the sequence of bases on the other strand. DNA's unique structure enables the molecule to copy itself during cell division.
When a cell prepares to divide, the DNA helix splits down the middle and becomes two single strands. These single strands serve as templates for building two new, double-stranded DNA molecules - each a replica of the original DNA molecule. In this process, an A base is added wherever there is a T, a C where there is a G, and so on until all of the bases once again have partners.
In addition, when proteins are being made, the double helix unwinds to allow a single strand of DNA to serve as a template.
This template strand is then transcribed into mRNA, which is a molecule that conveys vital instructions to the cell's protein-making machinery. Where is DNA found? What is DNA made of? What does DNA do? How are DNA sequences used to make proteins? Genes only make up a small percentage of the genome, and the rest is composed of intergenic regions bottom that do not code for proteins. How much protein a given gene ultimately produces, or whether it is allowed to make any at all, is determined by its gene expression.
In the case of the genome, any non-protein-coding sequence that is functional would presumably have some effect on how a gene is expressed; that is to say, a functional sequence in some way regulates how much protein is made from a given coding DNA sequence. It is the difference in the composition of proteins that helps give a cell its identity. Since every cell contains the exact same DNA and genome, it is therefore the levels of gene expression that determine whether a cell will be a neuron, skin, or even an immune cell.
Whereas the Human Genome Project primarily used the technique of DNA sequencing to read out the human genome, actually assigning roles to and characterizing the function of these DNA bases requires a much broader range of experimental techniques. These approaches included, among others, sequencing RNA, a molecule similar to and made from DNA that carries instructions for making proteins, and identifying regions of DNA that could be chemically modified or bound by proteins [].
Researchers picked these methods because they each give clues as to whether a given sequence is functional i. Additionally, proteins that bind to DNA influence whether a gene is expressed, and chemical modifications of DNA can also prevent or enhance gene expression. Each of these approaches can identify sequences within the genome that have some sort of biochemical activity, and to add to the usefulness of this project, the labs conducted these techniques in multiple cell types in order to account for natural variability.
So what did they ultimately find? Many scientists already suspected this, but with ENCODE, we now have a large, standardized data set that can be used by individual labs to probe these potentially functional areas. Likewise, because it was such a large project with strict quality controls, we can be sure that the data are reproducible and reliable.
Although the main benefits stemming from this project may not be realized for some years similar to the Human Genome Project , at the moment there are already some areas where this enormous data set will be useful. There are a host of diseases that seem to be associated with genetic mutations; however, many of the mutations that have been discovered are not within actual genes, which makes it difficult to understand what functional changes the mutations cause.
Using the data from the ENCODE project, researchers will be able to hone in on the disease-causing mutations more quickly, since they can now associate the mutations with functional sequences found in the ENCODE database.
0コメント