Nucleic acids are an acidic substances present in the karyon of cells and carry familial information in the cells. The nucleic acid consists of two subdivisions, nucleotide and nucleoside. When all three constituents of the nucleic acid, that is sugar, phosphate, and bases are present in a molecule, so it is called nucleotide and nucleoside when phosphate is absent. In cellular metamorphosis nucleotide have assortment of functions. They are energy currency in metabolic exchanges, the indispensable chemical links in the response of cells to endocrines and other exciting agents, structural constituents of an array of enzyme cofactors and metabolic intermediates. Most significantly, bases are the component of nucleic acid ; deoxyribonucleic acid ( DNA ) and ribonucleic acid ( RNA ) , the molecular depositories of familial information. The construction of every protein, cellular constituent, is a ultimate consequence of information programmed in the nucleotide sequence of a cell ‘s nucleic acids. “ The ability to shop and convey familial information from one coevals to the following is a cardinal status for life. ”
Deoxyribonucleic Acid ( DNA )
Deoxyribonucleic Acid is a supermolecule found in all life cells specifically in the chromosome and few in cytol every bit good in the chondriosome and chloroplasts. It is normally dual isolated construction and individual strand in few viruses like Parvovirus. The Deoxyribonucleic acid was foremost isolated by the Swiss Physician Friedrich Miescher in 1969, and he discovered in a little substance in the Pus of cast-off surgical patchs. Phoebus Levene identified base, sugar, and phosphate as nucleotide units in the twelvemonth 1919.
Deoxyribonucleic Acid, ( n.d )
Structure of Deoxyribonucleic Acid ( DNA )
The most recognized and the exact construction of the Deoxyribonucleic Acid was foremost introduced by J.D.Watson and F.H.C.Crick in the twelvemonth 1953.They deduced that DNA is dual spiral construction.The tax write-off was based on two major groundss:
They observed that sum of Thymine is ever equal to amount of Adenine and C with G. This is known as Chagaff ‘s regulation. ( Garner,2005 )
By the X-ray diffraction form of Wilkens and Franklin showed that the Deoxyribonucleic Acid molecule are coiling construction with reiterating units of base at every 0.34nm.
( Nelson et al, 2000 )
The dual spiral construction of the DNA is shown below:
Figure 1: The dual spiral construction of DNA.
Double spiral construction of DNA, ( n.d )
Deoxyribonucleic acid is a long polymer made from reiterating units called nucleotide. The Deoxyribonucleic Acid concatenation is 20A Angstroms broad ( 2.0A nanometer ) , and one base unit is 3.4A A ( 0.34A nm ) long. The Deoxyribonucleic acid dual construction is made of two polypeptide concatenation is in bend made of several bases which constitute of sugar, phosphate as anchor and base braces as complementary to each other which form H bonding. The dual spiral construction of DNA is right handed construction. ( Gardner et al, 2005 ) .The anchor of the DNA strand is made from jumping phosphate and sugar. The sugar in DNA is 2-deoxyribose, which is a pentose ( five-carbon ) sugar. The sugars are joined together by phosphate group ‘s signifiers a phosphodiester bond between the 3rd and 5th C atom of the sugar ring. The two polypeptide concatenation runs opposite way. One strand runs form three premier C of base to a five premier C of the other base and other from five prime to three premier Cs, jointly called as anti-parallel. In the dual spiral construction, the sugar phosphate ( anchor ) construction follow coiling way toward the outer border and the bases in the cardinal. The coiling coiling of the concatenation around each other consequence in the formation of major and minor channels. ( Becker et al, 2006 ) As mentioned, the polypeptide concatenation is made of several bases and bases are made of three constituents as shown below:
Sugar ( Deoxyribose )
Adenine ( A )
Guanine ( A )
Cytosine ( C )
Thymine ( T )
( Gardner et al, 2005 )
The construction of each constituents of base:
1 ) Deoxyribose Sugar 2 ) phosphate
3 ) Bases
a ) Purine
Adenine ( A ) Guanine ( G )
B ) Pyrimidine
Cytosine ( C ) Thymine ( T )
Figure 2: Components of DNA base. ( Bender, 2005 )
Function of Deoxyribonucleic acid
The Double spiral nature of the DNA accomplishes a alone map to hive away and convey familial information over long period of clip.
The construction of DNA determine the map
The base coupling of A with T and G with C makes the possibility of exact duplicate of Deoxyribonucleic acid that shop exact information to inherited to the progeny and the absence of OH group in DNA aid to forestall from formation of cyclic phosphate ester, and in bend prevented from hydrolization by base. The Deoxyribonucleic acid is methylated to one of the Pyrimidine base T which is helpful in prevent attacking from the enzymes nuclease. The dual nature of DNA provides protection against the chemical onslaught because of the H adhering between bases provide the first line of the defence, since bases are hydrophobic, they stack together and do a surface non-susceptible to the chemical onslaught to the Deoxyribonucleic acid. All the bases are stacked upon one another in the cardinal part of the Deoxyribonucleic acid, in making so, H2O is excluded from stack of the bases, where this is “ dry ” part of the bases makes any H2O soluble compounds hard to make bases and interrupt it. ( Gardner, et Al, 2005 ) The Deoxyribonucleic acid is design in such a manner that it forms major and minor channels which plays of import function in interaction with assortment of molecule with DNA. ( Becker, et Al, 2006 ) . The presence of sugar “ Deoxyribose ” in the polypeptide concatenation makes C to carbon bonds which are much resistant to the chemical onslaught under all conditions except at certain strong acids at high temperature. The N-glycosidic bond between the base -sugar and larger figure of H bonding helps in stableness of the Deoxyribonucleic acid. ( Gardner et al, 2005 )
Ribonucleic Acid ( RNA )
Ribonucleic Acid is chiefly found in the cytol of the cell. RNA is largely non familial and it act as familial stuff in some works viruses like Tobacco Mosaic viruses. The basic construction of RNA is similar with few differences and RNA is largely individual stranded.
Structural differences of RNA with DNA
RNA and DNA are both nucleic acids, but differ in three chief ways. First, unlike DNA which is double-stranded, RNA is a single-stranded molecule and has a much shorter concatenation of bases. Second, DNA contains deoxyribose ; where as RNA contains ribose ( DNA lacks hydroxyl group attached to the pentose ring in the 2 ‘ place ) . This OH group makes RNA less stable than Deoxyribonucleic acid because it is more susceptible to hydrolysis. Third, the complementary base to adenine is non thymine in RNA, but instead U, which is an unmethylated signifier of T. ( Lodish, 2008 ) . In RNA, bases in the concatenation are joined by3 iˆ? , 5 iˆ?phosphodiester bonds.
Figure 3: Chemical construction of RNA
Ribonucleic Acid ( n.d )
The individual polypeptide concatenation of RNA is made of three constituents as DNA except one of the bases of Pyrimidine is replaced by Uracil. The constituents of ribonucleotide are shown below:
Sugar ( Ribose )
Adenine ( A )
Guanine ( A )
Cytosine ( C )
Uracil ( U )
( Becker et al, 2006 ) & A ; ( Gardner et al, 2005 )
The construction that are different from Deoxyribonucleic acid are shown below and other constituents are every bit same as Deoxyribonucleic acid as shown in ( figure 2 ) except sugar and one of the pyrimidine base as mentioned above and shown below.
Sugar ( Ribose ) 2 ) Bases ( Pyrimidine )
Uracil ( U )
Figure 4: Ribose sugar and Uracil. ( Bender, 2003 )
The map of RNA
Ribonucleic acid does the interlingual rendition of the information stored in Deoxyribonucleic acid in to amino acerb sequence of protein. In interlingual rendition the DNA service as templet and work harmonizing to the messenger RNA and the transfer RNA carry peculiar amino acid to take part in the procedure of interlingual rendition. The rRNA is the major demands of the ribosome for the protein synthesis and provides specific adhering sites for the protein synthesis. ( Hartl, 2001 ) The RNA provides selective binding with other molecules because of its individual isolated construction provides flexibleness of flexing back on to itself allows one parts of the molecules to organize a weak H adhering with the other portion of same molecules. ( Alberts, 2008 )
Type of RNA and maps based on their construction:
A ) Messenger RNA
The information stored in the Deoxyribonucleic acid is copied into messenger RNA, since the messenger RNA is transcribed on DNA ; its base sequence is complementary to that of the section of DNA on which it is transcribed messenger RNA has five premier cap and the poly ( A ) tail that aid proper binding of the messenger RNA to the ribosome ( Eukaryotes ) .when the individual messenger RNA is used for coding a cistron called monocistronic ( eucaryotes ) and coding for more than one is called polycistronic ( Prokaryotes ) .It has get downing codon AUG and halt codon AUG, UGA, UUG. ( Becker et al, 2006 )
Figure 5: construction of messenger RNA ( Eukaryotes )
( Becker et al, 2006 ) & A ; ( Harlt et al, 2005 )
Function of messenger RNA
The messenger RNA carries information on the sequence of amino acid for the protein synthesis. The 5 iˆ? cap in mRNA provides protection from the nuclease that attack the RNA at 5 iˆ?end and besides place messenger RNA on the ribosome for induction of translocation particularly in eucaryotes. The poly ( A ) tail provides protection against the nuclease onslaught and interacts with specific protein involved in transporting messenger RNA to cytoplasm. It besides helps to transcribe the messenger RNA molecule. Deoxyribonucleic acid has useless noncoding DNAs ( Eukaryotes ) , so that messenger RNA is necessary in the remotion of noncoding DNAs by spliceosome. ( RNA protein complex ) ( Becker et al, 2006 ) & A ; ( Bhagavan, 2002 )
B ) Transfer RNA
Transportation RNA is RNA molecule has inverted ‘L ‘ construction or clover leaf construction. It has anti-codon cringle that make base brace with the messenger RNA for specific amino acids. Amino acids are bind to tRNA through ester linkage to the three premier OH by peculiar messenger RNA to organize charged tRNA.This activated transfer RNA with the messenger RNA codifications at the peptidyl adhering site and the aminoacyl adhering site of the ribosomes. ( Becker et al, 2006 )
Figure 6: Secondary construction of transfer RNA
Secondary construction of transfer RNA ( n.d )
Function of transfer RNA
When the information of messenger RNA ranges to tRNA it brings interlingual rendition of mRNA sequence into aminic acerb sequence of the protein. The L-shaped third construction maximizes the length of the base brace by stacking them into two sets organizing long drawn-out part. The two parts of each the drawn-out part are non aligned absolutely and therefore it bends somewhat. This alliance allows the base brace to stack on each other and provide stableness. ( Weaver, 2002 ) The folded nature of the anti-codon anchor into peculiar form provides base partner offing with corresponding codons. The distorted construction of the transfer RNA is said to supply its decrypting map when necessary. The fond regard of the amino acid to tRNA through ester linkage to the 3I„ OH to organize activated or charged transfer RNA and this charged transfer RNA is responsible for partner offing with mRNA codons in appropriate site of the protein. The charged transfer RNA recognizes appropriate codon with messenger RNA in the peptidyl site ( P ) and aminoacyl site ( A ) of the ribosome and leave through issue site. ( Weaver, 2002 )
C ) Ribosomal RNA
Ribosomal RNA, the name suggests it is found in the ribosome. In the cells that are synthesising proteins, negatron micrographs has shown that ribosomes are associated in a bead like threading called poly-ribosomes formed by the fond regard of the ribosomes to a individual molecule of mRNA.The ribosomal units in the procaryotes are 70s ribosomes and 80s in eucaryotes. This ribosome ‘s are farther dissociated into fractional monetary units of 50s and 30s in procaryotes and 60s and 40s in eucaryotes, because messenger RNA of the originating aminoacyl transfer RNAs can non adhere straight to 70s and 80s ribosomes. ( Ahluwalia, 1985 )
. Function of rRNA
rRNA is used in constructing the ribosome ‘s and that moves along the messenger RNA and the binding of ribosome with the messenger RNAs take topographic point at 5 iˆ? terminal of the messenger RNA as shown in the ( fig 5 ) and it checks the suited codification of mRNA.The messenger RNA and transfer RNA transporting the first amino acid bind to smaller ribosomal fractional monetary unit in its proper orientation by agencies of particular nucleotide sequence called mRNAs ribosome binding site, besides known as radiance -Dalgarno sequence.
( Lodish et Al, 2008 )
General map of RNA based on the construction:
RNA construction has an OH-group attached at the 2A?carbon of ribose and this 2A?-hydroxyl group in RNA Acts of the Apostless as nucleus loving, assailing the phosphodiester bond. It consequences in less opportunity of hive awaying the information. On the other manus this hydroxyl group on C two of ribose makes RNA more apt by assailing and hydrolysis the phosphodiester bond at around PH 7. This stableness divides RNA into mononucleotides by alkalic solution. The C two hydroxyl group of RNA provides a chemically reactive group that takes portion in RNA- mediated contact action and as a consequence RNA like ribosomal RNA plays a catalytic function in the formation of peptide bond, by exact sequencing the amino acids during protein synthesis and flow of information is accurate. ( Lodish et Al, 2008 ) .Presence of Uracil in RNA gets easy folded forming secondary construction. During folding, Uracil gets brace with A in which they will stabilise the secondary construction of RNA. Its presence besides helps in heightening the smooth flow of familial information in the exact sequence of aminic acids during protein synthesis. Uracil is besides a reactive base since it does non hold a methyl group that prevents the renaturation of spiral and being receives immediate familial information. ( Lodish et Al, 2008 ) . Beside this individual stranded construction besides provide flexibleness in bending and signifier weak H bond with same portion of molecules and supply selective binding with other molecules. ( Alberts et al, 2008 )
Therefore, DNA and RNA are the of import molecular depositories for familial information because they store and transmit information signifier one coevals to other over long period of clip and can convey in development.