DNA is the macromolecule base of inheritance. It is a nucleic acid that contains the information of the hereditary characteristics of each living being and the sequences for the creation of amino acids that will generate the vital proteins for the functioning of organisms.
The DNA or DNA (acronym in English) are acronyms for deoxyribonucleic acid and its main function is the storage of all the information necessary for the expression of certain characteristics, in segments called genes or packaged in chromosomes.
In addition, the DNA transcribes the information of the amino acid sequences in the RNA or ribonucleic acid, so that these instructions can be protected from the nucleus to the ribosomes, which will translate the information to create the proteins (chains of amino acids).
Referring to what has been said above, it can be seen that the DNA is coding and the RNA is not coding but they work together for the transmission of genetic information.
The DNA begins to be studied in the year 1868 by Friedrich Miescher that he names together with the RNA as nucleic acids. The DNA description was first published in 1953 by Jamen Watson and Francis Crick, both awarded the 1962 Nobel Prize in Medicine.
The main characteristic of human DNA is its double helix structure also called helical.
Where is the DNA located?
In prokaryotic cells (no defined cell nucleus), DNA is found in the cytosol, along with the other elements that float in it. Thus. its replication is immediate, that is, it does not need to resort to other processes to transmit the genetic information at the time of cell division.
In eukaryotic cells (with defined cell nucleus), the DNA is located in the cell nucleus. There are 2 ways in which DNA transmits the genetic information inside:
Before cell division : it replicates and is packaged with other molecules and proteins forming a larger molecule called chromosome. In this way, during mitosis, the 2 daughter cells will carry a copy of the original DNA.
For the translation or synthesis of proteins: the information of the sequences of 3 nitrogenous bases (codon) that will determine the functions of the DNA proteins of each organism need the messenger ribonucleic acid (mRNA) to travel safely out of the nucleus, towards the ribosomes
What are the functions of DNA?
DNA is characterized because it must fulfill 2 fundamental functions:
- Replication : must be able to replicate. In this sense, a DNA chain contains 2 strands of information that can be replicated in another 2 double strands.
- Expression : must be able to use the information to express hereditary characteristics or to encode proteins for the proper functioning of the organism.
DNA is a macromolecule with a double helix structure. The 2 strands that form the DNA go in reverse directions joined by their nitrogen bases (Adenine, Guanine, Cytosine and Thymine). It is for this reason that the structure of DNA is usually referred to as an inverted ladder .
What are the parts of the DNA?
The DNA is formed by deoxyribonucleotides, chains of nucleotides where each unit, in turn, is made up of 3 parts:
- a 5-carbon sugar molecule (deoxyribose for DNA and ribose for RNA),
- a phosphate group and,
- 4 nitrogenous bases (Adenine, Guanine, Cytosine and Thymine in the DNA; Adenine, Guanine, Cytosine and Uracil for RNA).
Replication of DNA
DNA replication occurs before the cell divides and consists of obtaining identical copies of the fundamental cellular information for transfer from one generation to another, thus constituting the basis of genetic inheritance.
The rolled DNA ( chromosome ) is untangled by the topoisonerase enzyme so that the helicase enzyme then acts by breaking the hydrogen bonds of the nitrogen bases (Adenine, Guanine, Cytosine and Thymine) to separate the 2 strands.
Each strand has a directionality and each end is called 5 ‘and 3’ (five cousins and three cousins), since it is only possible to add nucleotides at the 3 ‘end, that is, the direction of elongation will always be from 5’ to 3 ‘.
With this in mind, the nucleotides that will match the information of a strand will be added by the DNA polymerase in the 5 ‘to 3’ direction, where the hydrogenated Adenine bases always bind with the Thymine, the Thymine always with the Adenines, the Guanina always with the Citosina and the Citosinas always with the Guanina.
The nucleotide sequence established in a strand of DNA is transcribed into a messenger RNA (mRNA). The transcription of the DNA into the corresponding mRNA is similar to the process of DNA replication, in the sense of the association of the nitrogenous bases.
In this way, the hydrogenated Adenine bases bind with the Uracil, the Timina continue to always bind to the Adenina, the Guanina always with the Cytosine and the Cytosine always the Guanine.
Once the transcription is finished, the corresponding mRNA will transport the information to the ribosomes to begin with the translation or synthesis of proteins.
DNA and RNA
The DNA and RNA are nucleic acids together and are responsible for maintaining, replicating, store and transport the genetic information that defines each living being. Thanks to this information, the unique features of
The DNA means deoxyribonucleic acid, has a deoxyribose sugar and its nitrogen base is composed of: adenine, cytosine, guanine and thymine. It is characterized by having 2 strands rolled together to form a double helix.
In turn, RNA, that is, ribonucleic acid, contains ribose sugar, its nitrogen base is formed of: adenine, cytosine, guanine and uracil. It consists of a single strand.
However, both are nucleic acids composed of sugars, a phosphate group and a nitrogen base.
DNA, chromosome and genes
DNA is the helical chain that contains the genetic and protein synthesis information of each organism. It is packaged in chromosomes at the time of meiosis or cell division, preparatory phase so that the daughter cells each have an exact copy of the original DNA.
Instead, a gene is a segment of the DNA chain that defines or expresses a certain inherited characteristic.
Recombinant or recombined DNA is a genetic recombination technology, that is, they identify genes (segments of DNA that express certain characteristics of an organism), combine them and create new sequences. That is why this technology is also called in vitro DNA .
Mitochondrial DNA is a fragment of nucleic acid in mitochondria . The mitochondrial genetic material is inherited exclusively by the maternal part. Mitochondrial DNA was discovered by Margit MK Nass and Sylvan Nass using the electron microscope and a mitochondrial DNA sensitive marker.
Mitochondria are small organelles within eukaryotic cells, in order to produce energy for the cell to fulfill its functions. However, each mitochondrion has its own genome and its cellular DNA molecule.