Home » Health » Dna (Deoxyribose nucleic acid)

Dna (Deoxyribose nucleic acid)

  • What does Dna (Deoxyribose nucleic acid) mean?
  • Deoxyribose Nucleic acid or, in brief, DNA is a nucleic acid that carries the genetic instructions necessary for the vital functions and biological evolution of all organisms and some viruses. The primary role of DNA is long-term hiding of information. DNA because it contains the information needed to construct other components of the cell, such as proteins and RNA; A template, a template, or a prescription. DNA fragments containing these genetic information are called genes. But other DNA sequences have structural functions (such as determining the shape of chromosomes) and others help to regulate how this genetic information can be used (in which cells and under what conditions).

 

  • Chemically, DNA is made up of two long polymers, consisting of simple units called nucleotides. The backbones of these polymers come from sugar and phosphate groups linked together by ester bonds. These two yarns run counter to each other. One group of four types of molecules, called bases, is attached to each sugar group. The sequence of these bases along the backbone of DNA encodes genetic information. During protein synthesis, this information identifies the amino acid sequence of the protein as it is read through the genetic code. During this process, the information in DNA is copied into RNA, another nucleic acid with a structure similar to DNA. This process is called transcription.

 

  • In the cells, DNA is contained within structures called chromosomes. Prior to cell division, chromosomes are mapped, while DNA replication occurs. DNA is located in the cytoplasm of the prokaryotes (ie bacteria and backgrounds) while the eukaryotes (ie animals, plants, fungi and protists) contain DNA in the cell nucleus. Chromatin proteins (such as histones) in chromosomes constrict and organize DNA. These compact structures regulate the interactions between DNA and other proteins to control which parts of the DNA are read.

 

  • Properties of DNA
  • It is a polymer composed of units called nucleotides. The DNA chain is between 22 and 26 Ångström (2.2-2.6 nanometers) wide and a nucleotide unit is 3.3 Å (0.33 nm) long. Although each unit is very small, DNA polymers are enormous molecules composed of millions of nucleotides. For example, chromosome # 1, the largest human chromosome, is about 220 million base pairs long.
  • Half of the DNA comes from the female individual and half from the male individual. In vivo DNA is not a single molecule, but a pair of tightly wrapped molecules. These two long threads form a double helix, wrapped together like an ivy. The nucleotide units comprise a sugar, a phosphate and a base. Sugar and phosphate form the backbone of the DNA molecule, and the base interacts with the other DNA strand in the double helix. Generally, a base linked to a sugar is called a nucleoside, a sugar and one or more phosphates are linked, and a base is called a nucleotide. Multiple nucleotides are called polynucleotides linked to each other.

 

  • The backbone of the DNA strand consists of amorphous sugar and phosphate residues. The sugar in the DNA is 2-deoxyribose, which is a pentose (five-carbon sugar). The group of phosphates between the carbon number 3 of one of the two adjacent sugars and the carbon number 5 of the next connects the sugars together forming a phosphodiester bond. The phosphodiester bond is one direction of the DNA strand because it is asymmetric. The direction of attachment of the nucleotides in a double-stranded thread is the opposite of the direction of the other strands. This order of DNA strands is called anti-parallel. The asymmetric ends of the DNA strands are called 5 ‘(five bases) and 3′ (three bases), a 5 ‘end phosphate group and 3’ ends carry a hydroxyl group. One of the major differences between DNA and RNA is the sugar they contain, and ribose is another pentose sugar instead of 2-deoxyribose in RNA.

 

  • The hydrogen bonds between the bases bound to the double-stranded two strands stabilize the DNA. The four bases in DNA are called adenine (abbreviated as A), cytosine (C), guanine (G), and thymine (T). These four base sugar-phosphates bind to one nucleotide, for example & quot; adenosine monophosphate & quot; is a nucleotide.

 

  • The bases are classified into two types: adenine and guanine, purine derivatives, which are heterocyclic compounds formed by fusing five and six member rings; Cytosine and thymine are pyrimidine derivatives, consisting of a six-membered ring. Another base, uracil (U), can be found in DNA, which is rarely the end result of cytosine degradation. RNA, chemically similar to DNA, contains uracil in place of thymine.

 

  • Grooves
  • Two helical filaments form the DNA backbone. Two voids or cavities can be found by following the spaces between these yarns. These cavities are adjacent to base pairs and can form a place to connect to them. These cavities are not exactly the same size because they are not directly opposite each other. The major cavity is 22 Å wide and the minor cavity is 12 Å wide. It is much easier to reach the sides of the bases because of the narrowness of the small cavities. For this reason, proteins such as transcription factors, which bind to certain base sequences in DNA, come into contact with the edges of the bases in large pores. This can be different in some regions of the cellular DNA (see section “Alternative double stranded structures” below), but even there, they are named according to differences in size that would be seen if the DNA were to take the normal B shape.

 

  • Base matching DNA
  • One type of base in one thread of DNA and one base type in the other. This is called complementary base pairing: the purines form hydrogen bonds with pyrimidines, A binds only to T, and only C binds to G in C. Two bases connected to each other in a double helix are called a base pair. Double-stranded stable flanking also has hydrophobic effect and pi stacking, independent of DNA sequence. Because hydrogen bonds are weaker than covalent bonds, they can easily break off and form again.

 

  • Thus, the two strands of the DNA chain can easily be separated from one another like a zipper, either by mechanical force or at high temperature. As a consequence of their completeness, all information in a strand of DNA in a strand of DNA is copied in each strand, which is essential for DNA replication. In fact, specific and reversible interactions between complementary base pairs are essential for the vital functions of DNA.

 

  • Two types of base pairs form different numbers of hydrogen bonds, two hydrogen bonds of AT, and three hydrogen bonds of GC (see figure). Hence GC pairs are stronger than AT base pairs. Thus, the length of the DNA double helix and the percentage of GC base pairs that make up it are the determinants of the binding power of the two DNA strands.

 

  • The yarns of long DNA with high GC are more tightly connected to each other, while the yarns of short length with high AT rate are weaker than each other. In biology, the AT rate is high in areas where DNA double strand breaks up easily, such as the TATAAT Pribnow box in some promoters. To measure the power of this interaction in the laboratory, the temperature, the melting temperature, which is required to break the hydrogen bonds, is determined (this is also called the Tm temperature).

 

  • After all the base pairs in the DNA double strand have melted, the strands are disintegrated and continue to exist as two independent molecules in the solution. These two single-stranded DNA molecules do not have a single form, but some forms are more stable than others.

 

  • Meaning and opposite meaning
  • A DNA sequence is said to be “significant” if it has the same sequence as the messenger RNA copy from which it is synthesizing protein. The sequence in the other thread is called the “reverse semantic” sequence. Significant and inverse sequences can be found in different regions of the same DNA strand, meaning that both strands have both meaningful and meaningless sequences. Both prokaryotes and eukaryotes have an opposite meaning, that is, they produce RNA, which does not produce protein, and the function of these RNAs is still unknown. In one view, reverse-sense RNA is responsible for regulating gene expression through RNA-RNA base pairing.

 

  • In some DNA sequences, the concepts of meaning and adver- sation are confused because sometimes genes can overlap. In such cases, some DNA sequences function as a double, they code a protein when read through a thread, and a second protein when read along the other thread. In bacteria, there is evidence that such gene overlaps are associated with the regulation of gene transcription, whereas in viruses, overlapping genes allows more information to fit into a small viral genome.

 

  • Dna Supercoil
  • With a process called supercoiling, DNA can be twisted like a rope. A & quot; loose & quot; thread in DNA makes one complete revolution around the axis of the double helix at every 10.4 base pairs. But, if the DNA is twisted, the threads may be wrapped more tightly or loosely. If the DNA is twisted in the direction of helical wrapping, it is called positive superplumbing and the bases hold tightly together. If it is twisted in the opposite direction, DNA is called negative supper, and the bases are more easily separated from each other. Most DNA molecules in the environment are slightly superfluous negative, and enzymes called topoisomerases are responsible for this. A function of these enzymes is to eliminate the twisting that affects DNA strands during transcription and DNA replication.

 

  • Alternative double spiral structures
  • There are various forms of DNA (conformation). However, only A-DNA, B-DNA, and Z-DNA have been observed in living organisms. Which form of DNA depends on the DNA sequence it takes, the direction and amount of the supersurface, the chemical changes in the bases, and the properties of the solution (such as metal ion and polyamine concentration). The form “B” described above from these three forms is the most common under the conditions found in the cells.

 

  • Compared to form B, the shape of DNA is a wider spiral, the smaller groove is wider and shallow, and the larger groove is narrower and more compact. A-shaped nucleic acids may occur in hybrid-paired DNA-RNA complexes, which occur in non-physiological conditions, in DNA samples that have lost water, and in DNA, and RNA strands in the cell. The DNA fragments that undergo chemical change with methylation can show a larger formal change and take the Z shape. In this case, the yarns rotate about the spiral axis to form a left-handed spiral, which is the opposite of the more common B-shape. These extraordinary structures are recognized by Z-DNA binding proteins and are thought to be related to transcriptional control.

 

  • Quadrilateral structures
  • At the ends of linear chromosomes are specialized regions called telomeres. The main function of these regions is to make copies of the chromosomal ends via the enzyme telomerase. Since the enzymes normally copying DNA can not copy the extreme parts of the chromosomes, this transcription is made via telomerase. These specialized chromosome headers also protect the ends of the DNA and prevent the cellular DNA repair systems from being perceived as damage that needs to be repaired. Telomeres in human cells are typically single-stranded DNA extensions consisting of several thousand repeats of the TTAGGG sequence.

 

  • These guanine rich sequences stabilize chromosomal ends with stacking clusters of four base units instead of base pairs in normal DNA. Here, four guanines form a flat layer, which stacks on top of each other to form a stable G-quadruplex structure. The stabilization of these structures occurs by hydrogen bonding between the edges of the bases and a metal ion chelating in the middle of each quadruple-based unit. These G-quartets can also occur in other ways: this quadruple unit can be formed by folding a single thread several times, or these four bases can come together with the fact that each of the two or more different parallel threads provides a base for the common structure.

 

  • In the same order as these stacked structures, telomeres also form structures called telomeric (T-schism, English: telomere loops or T-loops). In these, single-stranded DNA is folded into a ring stabilized by telomeric binding proteins. The single-stranded DNA at the end of a T-RNA is linked to a double-stranded DNA region. At this junction, the single-stranded telomer DNA breaks the double strand of double stranded DNA and matches the base with one of the two stranded strands. This is a three-fold loop called a displacement loop or D-loop.

 

  • Chemical changes
  • Base changes
  • Chromosomes come into play when DNA is packaged in a structure called chromatin. This package affects the expression of the gene. The base change (modification) is associated with this packaging, such that the sites of the cytosine bases have undergone a high degree of methylation where there is little or no gene expression. For example, cytosine methylation and 5-methylcytosine occur, which is important for inactivation of the X chromosome. The average level of methylation is noticeable from living organisms: there is no cytosine methylation in the worm Caenorhabditis elegans, whereas up to 1% of the vertebrate DNA can contain 5-methylcytosine. Although 5-methylcytosine is an important base, its deamination results in a thymine base, which is why methylated cytosines tend to mutate. Other base modifications include adenine methylation in bacteria and the “J-base” that occurs at the end of uracil glycosylation in kinetoplasties.

 

  • DNA damage (Mutation)
  • The DNA may be damaged by various mutagens, resulting in a change in the DNA sequence. Among the mutagens, oxidizing agents, alkylating agents and high-energy electromagnetic radiation (such as ultraviolet light and X-rays) can be cited. The type of damage that occurs in DNA depends on the type of mutagen. For example, ultraviolet light damages DNA by forming thymine dimers (thymine dimers). In contrast, oxidizing factors such as free radicals or hydrogen peroxide can cause damage to a variety of different species, such as base exchange (especially guanosine) and two-strand breaks. Every human cell receives 500 base-oxidant damage per day. The most harmful of these oxidative damages are double chain breaks because their repair is difficult, they can lead to point mutations, insertions and deletions in DNA sequences as well as chromosomal translocations.

 

  • Most mutagens enter the gap between two base pairs, which is called intercalation. Most intercalators are aromatic and planar molecules, such as ethidium bromide, daunomycin and doxorubicin. In order for an intercalator to be able to enter between two base pairs, the opening of the DNA strand must be twisted in the opposite direction.

 

  • These prevent transcription and DNA duplication, poisoning and mutations. Thus, DNA intercalators are often carcinogenic, examples of which include benzophenone diol epoxide, acridine derivatives aflatoxin and ethidium bromide. Nevertheless, because of their ability to inhibit DNA transcription, these toxins are also used chemotherapy to block rapidly growing cancer cells.

 

  • Biological functions
  • DNA is found in linear chromosomes in eukaryotes and circular chromosomes in prokaryotes. A set of chromosomes in a cell is called its genome; The human genome consists of about 3 billion base pairs located within the 46 chromosomes. The information that encodes proteins and other functional RNA molecules is contained in the sequence of DNA fragments called genes. Transmission of genetic information in the genome occurs through base pairing.
  • For example, the transcription of a DNA sequence as a complementary RNA sequence during transcription is possible by drawing between the DNA and the correct RNA nucleotides. During the so-called protein translation (translation) process, a protein that scatters this RNA sequence is synthesized, resulting in base pairing between RNA nucleotides.

 

  • Another important biological process is duplication of DNA, which is a copy of genetic information in the cell. Details of these functions are processed in other materials; Where the interactions between DNA and other molecules fulfilling the functions of the genome are addressed.

 

  • Genes and genomes
  • More information you key use this keywords: Cell nucleus, chromatin, chromosome, gene, non-coding DNA
  • The DNA that makes up the genome is found in the cell nucleus in eukaryotes, and also in the mitochondria in small amounts. The DNA in the prokaryotes is in the cismin called the irregularly shaped nucleoid in the cytoplasm.
  • The information encoded by the genome is contained in genes, and this information, carried by a living individual, is called its genotype. The gene is a hereditary unit and is defined by a DNA sequence that determines a particular feature of the organism. In addition, there are also sequences (such as promoters and promoters) that regulate the transcription of this DNA region.
  • In most biological species, only a small fraction of the sequences in the genome encode proteins. For example, only 1% of the human genome encodes protein exons, whereas 50% of human DNA consists of self-repetitive sequences that do not encode proteins.
  • The availability of DNA encoding so many proteins in eukaryotic genomes and the large differences in genomic size (“C-value“) of the species is not yet understood and is known as the “C value“.
  • Non-coding DNA sequences, however, still encode RNA molecules that do not functionally function, which also play a role in the regulation of gene expression.

 

  • Some coding DNA sequences play a structural role for chromosomes. Telomer and centromere typically contain very few genes but are important for the function and stability of chromosomes. An important type of non-coding DNA in humans is pseudogenes, which are copies of genes that have become mutationally inoperable.
  • These DNA sequences are usually molecular fossils, but sometimes they can be the raw material for the formation of new genes, resulting in gene duplication and divergent evolutionary processes.

 

  • Transcription and translation
  • Genes are DNA sequences that encode functional molecules, which determine the phenotype of a living thing. In the case of proteins encoding genes, the DNA sequence defines a messenger RNA sequence, which specifies the sequence of one or more proteins. The relationship between the DNA sequence in the genes and the amino acid sequence in the proteins is determined by the biological cycle (translation) rules, which are collectively summarized by the genetic code. The genetic code consists of triplet ‘words‘ (eg ACT, CAG, TTT), which correspond to sequences of three nucleotides, which is called a triplet codon.

 

  • In the transcription, the codons of a gene encoding a protein are first copied by RNA polymerase into a messenger RNA. This RNA copy is then decoded by a ribosome; The ribosome reads it by base mapping between the messenger RNA and the carrier RNAs carrying the amino acid. There are 64 possible codons (4 ^ {3}) since four bases can have 3 combinations. These are twenty standard amino acid codes, so most amino acids fall into multiple codons. In addition, there are three ‘stop’ or nonsense codons at the end of the protein coding region, which are the TAA, TGA and TAG codons.

 

 

 

  • DNA Combination
  • Cell division is necessary for the proliferation of living things and the growth of (multi-celled living things). But when a cell divides, it has to copy its DNA so that the two puppies have the same genetic information on the main cell. The double stranded structure of DNA provides a simple mechanism for DNA duplication (DNA duplication). The two strands are separated, then the complementary sequence of each strand is produced by an enzyme called DNA polymerase. This enzyme chooses the right one for each synthesizer necessary for synthesizing the thread by base pairing and adds it to the stranded thread. Because the DNA polymerase can extend a DNA strand only in the 5 ‘- 3’ direction, there are different mechanisms for the replication of antiparallel strands of a double strand. Thus, the base in the old thread determines the bases added to the new thread, eventually obtaining a perfect replica of the cell DNA.

 

  • Interaction with proteins
  • All the functions of DNA depend on its interaction with proteins. Some of these protein interactions are non-specific, while in others they can be linked to a particular DNA sequence. Enzymes can also bind to DNA, and among them polymerases that transcribe DNA bases and transcribe for DNA redundancy are particularly important.

 

  • Binding proteins to DNA
  • Structural proteins bound to DNA are well understood examples of non-specific DNA-protein interactions. DNA found on chromosomes forms complexes with structural proteins.
  • These proteins organize DNA in a compact structure called chromatin. The binding of DNA to small, basic proteins called histones plays an important role in the formation of chromatin in eukaryotes; While in prokaryotes various other protein types are linked to DNA. Histones form a disk-shaped complex called nucleosomes, in which double-stranded DNA is wrapped around it twice.
  • The ionic bonds between the basic residues of the histones and the acidic phosphates of the sugar-phosphate backbone of DNA form a non-specific interaction, largely independent of the base sequence. Chemical variations of these basic amino acids include methylation, phosphorylation, and acetylation.

 

  • These chemical changes affect the interaction of DNA with histones, resulting in the accessibility of transcription factors to DNA and the rate of transcription. The high-mobility group proteins found in the non-specific DNA binding proteins found in the chromate bind to the twisted or distorted DNA. These proteins bend adjacent groups of nucleosomes to form larger scales and bring the chromosomes to the square.
  • A major group of proteins found among the binding proteins to DNA are single-stranded DNA binding proteins (also referred to as single-stranded DNA-binding proteins). In situ replication is considered to be the best understood member of this protein family of proteins, which function in the case of splitting of the helix, for example DNA replication, recombination and DNA repair.
  • These proteins stabilize single-stranded DNA, preventing it from forming stem-loops or destroying it by nucleases.

 

  • Unlike the proteins mentioned above, other proteins evolved to link to certain DNA sequences. The best researched ones are transcription factors, proteins that regulate transcription of the blob. Each transcription factor is linked to a set of specific DNA sequences, and it activates or inhibits the transcription of genes that have proximal sequences.
  • Transcription factors do this in two different ways. First, they bind the RNA polymerase responsible for the transcription, either directly or by means of the mediator proteins, resulting in the polymerase promoter being placed in close proximity and starting transcription is possible. On the other hand, transcription factors are linked to enzymes that degrade histones in the promoter; As a result of which the accessibility of the polymerase to DNA changes.
  • Since these DNA binding sequences can be found all over the genome of a living thing, changes in the activity of a transcription factor can affect thousands of genes. Thus, these proteins are often the target of signal transduction processes associated with processes that control environmental changes, cellular metamorphosis and development. The specificity of the interaction of these transcription factors with DNA stems from the protein’s contacts with the edges of the DNA bases, where they “read” the DNA sequence. Most of these interactions with the bases take place in the large trough, which is easily accessible to these bases

 

  • DNA-modifying enzymes
  • Nucleases and ligases
  • Nucleases are enzymes that cut DNA strands, catalyzing the hydrolysis of phosphodiester bonds. The nucleases that hydrolyze the nucleotides at the ends of the DNA strands are called exonuclease, whereas those that hydrolyze the strands at the ends of the strands are endonucleases. The most commonly used endonucleases in molecular biology are restriction endonucleases, which cut DNA in certain sequences. For example, the EcoRV enzyme shown in the picture on the left identifies the 6-base 5′-GAT | ATC-3 ‘sequence and cuts it at the point indicated by the vertical line. In the wild, these enzymes, as part of the restriction modification system, benefit from protecting bacteria against phages, digesting the phage DNA that enters the cell. In technology, these enzymes are used for molecular cloning and DNA fingerprinting.

 

  • DNA ligase enzymes combine cut or broken DNA strands. Ligases especially play a crucial role in delayed-strand DNA replication, because replication combines short DNA fragments that occur in the fork. They are also used in DNA repair and genetic recombination.

 

  • Topoisomerases and helicases
  • Topoisomerases have both nuclease and ligase activity. These proteins change the degree of superfluidity in DNA. Some of these enzymes cut off a thread of the DNA helix and turn it around, then recombine the DNA helix. Others of these enzymes cut off a thread of the DNA helix and allow the other thread to cut through it, then recombine the sheath. Topoisomerases are involved in many processes related to DNA, such as DNA replication and transcription.

 

  • Helicases are proteins with molecular motor properties. Nucleoside triphosphates use chemical energy carried in ATP, breaking hydrogen bonds between bases, and twisting the DNA double strand in the opposite direction to open it as single strands. These enzymes are necessary for processes involving enzymes that need access to DNA bases.

 

  • Polymerases
  • Nucleic acid polymerases are enzymes that synthesize polynucleotide chains from nucleoside triphosphates. The products they produce are copies of existing polynucleotide chains (called molds). These enzymes work by adding a new nucleotide to the 3 ‘hydroxyl group of the last nucleotide in a DNA chain. Therefore all the polymerases travel in the 5 ‘- 3’ direction. In the active region of these enzymes, the incoming nucleoside triphosphate matches the base with the template; Whereby the polymerase can synthesize a complementary string of the correct pattern. Polymerases are classified according to the type of mold they use.

 

  • In DNA replication, the DNA-dependent DNA polymerase makes a copy of a DNA sequence. Since it is vitally important that there are no errors in this process, most of these types of polymerases have proofreading activity. In these cases, rare errors in the synthesis reaction can be understood by the fact that the base pairing is not correct. If a non-compliance is detected, an exonuclease activity in the 3′-5 ‘direction is activated and the faulty base is removed. In most organisms, the DNA polymerases are housed in a large complex called the replizome, containing auxiliary subunits (such as DNA vigilantes and helicases).

 

  • RNA-dependent DNA polymerases are a special class of polymerases that replicate in the RNA strand as sequence DNA. Reverse transcriptases include this class, which are viral enzymes involved in the infection of cells by retroviruses. Telomerases are also included in this class, which is necessary for telomerisation. It is a distinctive feature of other enzymes such as ribosomal RNA, which is part of the heart’s own structure.

 

  • Transcription is carried out by DNA-dependent RNA polymerase, which copies the enzyme as a sequence RNA in the DNA strand. For transcription of a gene, the RNA polymerase is ligated to a region called the promoter on the DNA and separates the DNA strands. Then copy the genome sequence as an RNA chain, from where it comes to a DNA region called the terminator to stop there and break from the DNA. As well as DNA-dependent DNA polymerase, RNA polymerase II (the enzyme that transcribes most genes in eukaryotes) also acts as part of a large protein complex composed of various regulatory and helper proteins.

 

  • Genetic recombination
  • A DNA helicase usually does not interact with other DNA fragments, and even different chromosomes in human cells are located in different regions of the nucleus. The physical separation of different chromosomes in this way plays an important role in the functioning of DNA as a stable information repository. The times that the chromosomes interact with each other are only in the crossover where they enter the recombination. During the crossover, the two DNAs are coiled, a segment is displaced and the cut ends join.

 

  • Through recombination, genetic information is exchanged between chromosomes, and new gene combinations occur, which are thought to be important in increasing the efficiency of natural selection and in rapid evolution of new proteins.

 

  • Genetic recombination is also associated with DNA repair, especially in the double strand breakage reaction of the cell.

 

  • The most common form of chromosome wrapping is homologous recombination, in which two chromosomes have very similar sequences. Non-homologous recombination can be damaging to the cell because it can lead to chromosomal translocation and genetic abnormalities. The recombination reaction is catalyzed by enzymes called recombinases (e.g., RAD51).

 

  • The first step in the recombination is the formation of a double-stranded cut, which results in either an endonuclease or DNA damage. As a result of a series of steps partially catalyzed by recombinase, the two strands are joined by at least one Holliday link: one strand of each strand is stranded with the other strand complementary to the other strand. The Holliday junction is a tetrahedral structure, which travels along chromosomes by displacing one thread with another in two joined chromosomes. The recombination reaction terminates with the cleavage of the linkage and the recombination of the released DNA ends.

 

  • The evolution of DNA metabolism
  • The genetic information in DNA allows all modern living things to function, that is, to grow and multiply.
  • It is unclear, however, that DNA has performed this function throughout the 4 billion years of life’s history, suggesting that it is the RNA of the hereditary material that the oldest forms of life use. RNA may play a central role in the metabolism of primary cells because of its ability to transfer both genetic information and catalysis as part of ribozymes.

 

  • This ancient RNA world in which nucleic acids play both a role in both inheritance and catalysis may have influenced the evolution of today’s genetic code to four nucleotide bases. It is suggested that the number of bases encoding hereditary information may be balanced by four, with these two opposite effects, where the number of bases in a living thing will increase the efficiency of replication but the multiplicity of bases will increase the catalytic efficiency of the ribosomes.
  • However, there is no direct evidence of old genetic systems because it is not possible to obtain DNA from many fossils. The reason is that DNA exposed to environmental influences lasts for less than a million years and breaks down into small pieces in solution over time. There is an allegation that the old DNA is isolated, especially when a living bacterium is isolated in a salt crystal of 250 million years ago, but these claims are controversial.

 

  • Usage in technology
  • Gene engineering
  • In modern biology and biochemistry, recombinant DNA technology is used extensively. The recombinant DNA is an artificial DNA assembled from other DNA fragments. DNA fragments can be introduced into living beings by transformation through plasmid or viral vectors. Recombinant proteins can be produced using genetically altered living organisms that are generated in this way, which can be used in agricultural research and in medical research.

 

  • Forensic science
  • Forensic scientists can identify a perpetrator using DNA found in blood, semen, skin, saliva or hair found in a crime scene. This process is called genetic fingerprinting or genetic profiling. In DNA profiling, the lengths of the variable parts of the DNA containing repetitive sequences (microsatellite and minisatellite) are determined, which are compared in different humans.
  • This method is a very reliable method for recognizing a criminal. However, if the criminal code is infected with more than one person’s DNA, this identification can become complicated. DNA profiling was developed in 1984 by the British geneticist Sir Alec Jeffreys and was first used in forensic science in 1988 to convict Colin Pitchfork for the Enderby killings. Those who commit crimes can be forced to give a sample of their DNA in order to be stored in a database . In this respect, some old cases that had no evidence other than the crime of the DNA sample could be resolved. DNA profiling has also been used to identify the identities of victims of massacres.

 

  • Bioinformatics
  • The processing, searching and analysis of DNA sequences through the computer are among the topics of bioinformatics. Important advances in computer science have been traced through the development of methods for the storage and retrieval of DNA sequences, particularly for array search algorithms, machine learning and database theory.
  • Array searching and mapping algorithms are concerned with the presence of shorter string sequences in long strings of letters, which are developed for the detection of certain nucleotide sequences. The algorithms used by the text editor programs are extremely inefficient in the case of DNA sequences because of the small number of different characters that make up the DNA sequences. The sequence alignment problem associated with this is to find similar sequences and identify mutations that are different from each other.

 

  • These techniques are used in particular for multiple sequence alignment, phylogenetic relationships and protein function studies. The use of DNA sequences corresponding to the entire genome requires the recording of genes and their regulatory elements on these sequences. Identification of regions with the characteristics of protein or RNA encoding genes in DNA sequences is possible thanks to gene detection algorithms which allow scientists to predict a genetic product in advance,

 

  • DNA nanotechnology
  • DNA nanotechnology manufactures self-constituting, branched DNA complexes with useful properties using DNA-specific molecular recognition properties. DNA is not used to carry biological information, but as a structural material. In this way, two-dimensional periodic sequences and polyhedral-shaped three-dimensional structures were created. Nanomechanical tools and algorithmic structures have also been shown, and these DNA structures have allowed the regulation of other molecules (gold nanoparticles and streptavidin proteins).

 

  • DNA History and anthropology
  • Since the mutations that accumulate in DNA over time are then inherited, the information they carry is historically a history. Geneticists can make inferences about the evolutionary history of a living thing, its phylogeny, by comparing DNA knots. The phylogenetic field is a powerful tool in evolutionary biology. When comparing the DNA sequences of a fellow individual, community geneticists can be informed about the history of that community. This information can be used in various fields ranging from ecological genetics to anthropology. For example, the ten lost tribes of Israel, which are mentioned in the Torah, are defined by DNA findings.

 

  • DNA has also been used to identify family relationships, for example, in the American presidency, proving that there is a relationship between Jefferson and the descendants of Thomas Jefferson’s slave Sally Hemings. This use is similar to the use of DNA in the criminal investigations mentioned above. As a matter of fact, some of the investigations have been resolved by the DNA of the crime scene being coincident with the DNA of the relatives of the criminal.

 

  • History of DNA research
  • The DNA was purified by the first Swiss physician Friedrich Miescher, who in 1869 discovered a microscopic substance in the pus in the surgical dressings. Since it is found in cell nuclei (nucleus), it gave it the name “nucleus“. In 1919, Phoebus Levene, the nucleotide unit forming base, sugar and phosphates were identified. Levine DNA is a chain of nucleotide units linked together by phosphate groups. However, Levene thought that this chain was short and that the bases had a self-repeating sequence. In 1937, William Astbury obtained the first X-ray diffraction images showing that DNA had a regular structure.
  • In 1928, Frederick Griffith showed that it is possible to transfer the “straight” shape-determining characteristic of the pneumococcal bacteria to “wrinkled” pneumococcal bacteria, which is enough to mix dead “straight” bacteria with live “wrinkled” bacteria. Using this experimental system, Oswald Avery and colleagues Colin MacLeod and Maclyn McCarty showed that in 1943, DNA was the altering agent. In 1952, DNA confirmed the role of DNA in genetics by showing that the genetic material of the T2 phage was DNA in the Hershey-Chase experiment by Alfred Hershey and Martha Chase.
  • In 1953, James D. Watson and Francis Crick put forward the accepted structure of DNA today in Nature. The double-stranded molecular models were based on a single X-ray diffraction image, which was obtained in May 1952 by Rosalind Franklin and Raymond Gosling.

 

  • Another information they have based their models was that Erwin Chargaff had previously mapped DNA bases that he had specially communicated to them. The Chargaff rules play an important role in determining the double-stranded form of both B-DNA and A-DNA.
  • Experimental evidence supporting the Watson and Crick model appeared in five articles published in the same issue of Nature. Franklin and Gosling’s work was the first publication of their X-ray diffraction data and analysis method, which in part supported the Watson and Crick model.
  • In the same issue, there was a paper by Maurice Wilkins and two colleagues about the DNA structure, their analysis of in vivo B-DNA X-ray diffraction patterns supported two double-helix patterns proposed by Crick and Watson two pages behind. After Franklin’s death in 1962, Watson, Crick and Wilkins won the Nobel Prize in Physiology or Medicine. Nobel prizes at that time allowed only those who were alive to give a reward. The debate continues as to who should take credit for discovery.
  • In an influential presentation in 1957, Crick put forward the “Fundamentals of Molecular Biology” and summarized the relationship between DNA, RNA and proteins, summarized before the evidence had been fully assembled, and also expressed the “adapter hypothesis.” The confirmation of the duplication mechanism implied by the double-stranded structure was made by the Meselson-Stahl experiment published in 1958.
  • Other studies by Crick et al. Showed that the genetic code consists of non-overlapping base trilogens called codons, on which Har Gobind Khorana, Robert W. Holley and Marshall Warren Nirenberg solve the genetic code. These discoveries correspond to the birth of the molecular biology.

 

Dna (Deoxyribose nucleic acid)
Author: wik Date: 6:42 pm
Health

Wik's Random Content