Mysterious life-helix DNA
DNA (deoxyribonucleic acid) is the hereditary information material support: DNA makes up genes. The DNA molecule is a polynucleotide consisting of the base units called nucleotides, each nucleotide is composed of three elements:
a nitrogenous base, which may be adenine (A), cytosine (C), thymine (T) or guanine (G).
of a sugar molecule (sugar) called deoxyribose
one or more phosphate groups
Linear sequence of nucleotides – the order in which they are strung – is the primary structure of DNA. But like any complex molecule, DNA has several levels of structure. Primary structure does not fully describe the composition of the molecule, but must be deciphered and other levels of structure, in order to fully characterize.
In living cells, DNA exists predominantly two-chain form (two chains, or chains of nucleotides) and the secondary structure is given of the way in which the two strands are connected with each other, namely, the hydrogen bonding between base pairs nitrate the chain and the other. Nitrogenous bases can not connect anyway, but only in specific combinations: adenine binds to thymine always set (AT) and cytosine – guanine (CG). There are two issues that have been clarified by Crick and Watson in their model: one strand is DNA and how to connect them together.
The major contributing to whose clearance was four scientists mentioned the tertiary structure of DNA, the molecule that is specific three-dimensional form. Today, we know that DNA is in the form of a “double helix” as named Watson, the two strands twisting around one another at certain angles and distances between turns precise helical structure. To discover this structure tertiary Crick and Watson came famous.
Finally, DNA has a quaternary structure, a higher degree of organization, which refers to the interactions of DNA with other molecules, enabling it to carry out specific functions. In the cell, DNA is associated with proteins called histone molecules of forming a more compact structure called chromatin. In this form the DNA can be found in the cell nucleus.
In general, the DNA molecule looks like a large spirally wound, the sides are formed + deoxyribose phosphate groups, and the steps – of the nitrogenous base pairs AT and GC.
Today, we know all this, but imagine that 60 years ago, they were not known. No one could describe DNA even in summary form I described above. DNA molecule structure size was too small to be seen under a microscope, so everything had to be inferred indirectly through complicated calculations, interpreting results of specific analyzes, the assumptions often denied and rarely confirmed by transposing a huge scale DNA molecule image as an imagined and scientists.
It must be said that, overall, the molecular structure of the gene was, at that time, a great unknown. Today, many people know that genes are composed of nucleic acids, but at that time the idea was not accepted even by all the scientific community. Enough scientists believed that genes are made up of proteins capable of self-replication, while DNA is attributed only a structural role for the protein carrier. The Crick-Watson made light in this area, as it provided evidence to support the idea that genes are made up of nucleic acids.
On this foundation was built molecular genetics, from which we expect for the future, solving the many problems of humanity: hunger, diseases and more. Currently, no week passes without a lab in the world to announce that it has discovered something about a gene. But that would not have been possible without discovering the structure of DNA, the molecule that makes up genes polynucleotide, miraculous spiral whose composition is entered secret life.