Study Of Major Types Of Nucleic Acids Biology Essay

Nucleic acids are the substances found in the karyon of every life cells and it is the additive polymers of bases attached together and find their function as informational supermolecules. The two major types of nucleic acids are DNA and RNA. Both of them are compose of sugar, phosphate and bases. DNA chiefly serve as a depository of familial information where as RNA plays many functions in look of the information given by Deoxyribonucleic acid. Harmonizing to the theory of cardinal tenet given by Francis Crick, the information encoded in DNA is transportation to mRNA by the procedure of written text. And through the procedure of interlingual rendition the protein is manufactured by assorted RNAs in the ribosome within the cell cytol.

Transcription Translation

Deoxyribonucleic acid messenger RNA Proteins

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Move to cytoplasm through pores ( Within nucleus ) ( In karyon ) ( Inside ribosome )

( Becker et al, 2007 )

DNA-Deoxyribonucleic acid

Deoxyribonucleic acid is a nucleic acid ; it is in long polynucleotide concatenation and is normally a familial

Material where the familial information of all life cell/organisms is stored.However, in

Some instance RNA act like a familial stuff where DNA stuff is wholly absent,

E.g. in tobaccos mosaic assorted ( Gupta, 2001 ) .

The Deoxyribonucleic acid in all life cell is largely existed in dual isolated signifier and seldom observed

in individual isolated signifier, example-single stranded DNA in Parvovirus ( Gupta,2001 ) .

The Deoxyribonucleic acid in procaryotic cell occurred extremely twisted, round and associated with

interior side of plasma membrane, free of protein composite. In eucaryote it is found in

chromosome of karyon, chondriosome, cell cytol and chloroplast ( workss ) ( Conn & A ; Stump, 1976 ) .

Deoxyribonucleic acid Structure.












Fig.1 ( Nelson & A ; Cox, 2000 ) .

The DNA ( nucleic acid ) is nevertheless build up of four different types of edifice blocks

Called bases. Each of the base is composed of: a ) phosphate and

B ) Nucleoside moiety.This nucleoside consists of bases-a cyclic N incorporating

Compound ( supply stalls ) either dual ring purine base ( adenine and G ) or individual

pealing pyrimidine base ( C and T ) and pentose sugar ( 2’deoxy ribose )

( Deoxyribonucleic Acid ) .The basal T is usually in methylated signifier and

it is stable base which provide protection to DNA from enzyme nuclease.

Structure of four bases.

( Kratz, 2009 ) .Fig2

The sugar of DNA is 2’deoxyribose ( pentose ) , hydroxyl group ( OH ) is present merely at C 3aˆ?

Position but deficiency hydroxyl groups at C 2aˆ?position, unlike in RNA.In DNA a figure of

monomer nucleotide united to give long polynucleotide chain/macromolecule unit by the

formation of span called phosphodiester bond between two base at C 3aˆ?and C

5aˆ?end.The bases are side group anneal to the pentose sugar with the formation of glucosidic

linkage bond. Obviously in DNA molecule phosphate and sugar are the two primary back bonds

which are exposed outside of the spiral, fall ining together alternately and its hydrophilic in

nature. The side group ( basal brace ) are hydrophobic in nature, which is hinder inside of the dorsum

bond and signifier H bond between specific base coupling of the two opposite strand, so the

base themselves become to strong ( Gardner et al, 2005 ) .

Fig 3 DNA dual spiral.

( Synergistic Concepts in Biochemistry, 2002 ) .

Figure: 4. The chemical construction of DNA.

Deoxyribonucleic Acid ( n.d )

Harmonizing to Watson and Crick ( 1953 ) fig 3, DNA exists as a dual coiling construction,

Where one of the polynucleotide concatenation is complementary to another and it is twisted

together around a common axis and organize a right handed coiling construction. This dual

spiral of two complementary Deoxyribonucleic acid ironss are arrange in resistance way ( i.e.

antiparallel ) along the spiral, where one of the strand running in downward way from

5aˆ?carbona†’3aˆ?carbon and other complementary strand tally in 3aˆ?carbon a†’5aˆ?carbon

Direction ( Becker, 2007 ) .The two opposite strands are held together by the formation of

H bond between the specific base coupling and the base coupling is ever specific i.e.

A ever brace with T ( A=T ) by organizing two H bonds and G with

Cytosine ( Ga‰?C ) by organizing three H bonds. ( Gardner et al.2005 ) .The base coupling will be

non happened until and unless the base is non specific, so the Deoxyribonucleic acid sequences will be non in

self-generated and if it is specific sequence will be in self-generated mode. Antiparallel in

nature made DNA so stable. The base brace in DNA are stacked 3.4C? distance with 10 bases

braces per bend ( 360 ) of dual spiral and bases are perpendicular to each other. The dual coiling

Structure is rather stiff, syrupy with huge length and little diameter dwelling of child and

major channel, with 34A. The major channel is deep and broad for the site where most protein

Deoxyribonucleic acid interactions occur, whereas the minor channels are rather narrow and shallow. Diameter of

dual spiral is 20C? . ( Gardner. et Al, 2005 ) .

Forms of Deoxyribonucleic acid: Three major signifiers of Deoxyribonucleic acid are reference below base on their umber of

base braces, comparative humidnesss, construction, etc.

A signifier

B signifier

Z signifier

1, construction

Right handed

Right handed

Left handed/zigzag.


60 %

92 %




10 ( common in human ) 12

( Strickberger, 1976 ) .

Functions of DNA related to its construction.

The dual coiling construction and specific base brace present in Deoxyribonucleic acid severs as a mechanism for

the accurate replication/transmission of the familial information. Due to the complementary

strand of the dual coiling construction, each strand serve as a templet to stipulate the base

Sequence of a freshly synthesized complementary strand therefore, lead to the production of two

girl molecules of DNA, which are indistinguishable to that of parent DNA ( Conn & A ; Stumpf, 1976 ) .

Double spiral of DNA besides contains two types of channels ; they are major and minor channels.

The major channels are the site /space for the binding of other regulative proteins/non histone as

good as infinite for other strands of nucleic acids and minor channels are the sites for histone

binding. ( Bhagavan,2002 ) .

In dual spiral DNA, the bases are hinder/shield inside the coiling construction which is

hydrophobic in nature and many H bonds ( weaker than normal chemical bond ) are

signifier between the specific bases coupling of the complementary strand along the length of dual

spiral, at least two H bond for each base brace, therefore it maintain the high grade of

stableness and rigidness to the molecule ( Strickberger,1985 ) . At the same clip sugar and phosphate

Backboned are besides arranged alternately from outside and maintain connected each other by

phosphodiester bond.Therefore the base and back bond maintain DNA stableness and stored the

familial information for long times ( Nelson & A ; Cox, 2000 ) . However, in DNA due to

absence of OH ( present merely H -made stable ) group at C2 ‘ place, it prevent the formation of

cyclic phosphate ester therefore, less susceptible in hydrolysis at room temperature and will non assail

by the alkaline, since, H can non assail unlike in RNA ribose at C2’position hydroxyl

group is presence which act as nucleophile assailing the phosphodiester bond and lead in less

Opportunity of hive awaying familial information ( Lodish, 2008 ) .In DNA molecule it contain

thymine base alternatively of U for familial information storage. This is really of import in Deoxyribonucleic acid

because it contain methyl group which keep impersonal and cell ensured to mend the harm Deoxyribonucleic acid

cause by the obliteration of C with out damaged the other DNA. It can besides maintain the Deoxyribonucleic acid

construction stableness for long clip, since the T base is no reactive, therefore familial information

is stored for long clip and occur exact tallies of familial information.The methylated T

even prevent Deoxyribonucleic acid from chemical attracts/enzyme nuclease.If U is present alternatively of

T than it will forestall repairing of damaged DNA, more over mistake will take topographic point during

the flow of familial information and protein synthesis. ( Becker,2006 ) .In DNA, the base

and sugar are bounded each other by the formation of N-glycosidic bond, which assistance in

keeping the Deoxyribonucleic acid construction stableness at utmost pH ( Conn & A ; Stumpf,1976 ) .

Therefore DNAs chief map is to stored and convey the information /it act like “ direction

manual ” in its sequences and supply all the information needed ( Lodish,2008 ) .

Ribonucleic acid: Ribonucleic acid

RNA is besides one of the nucleic acid found in many beings including workss animate beings, viruses

and bacteriums ( Gupta,2001 ) .RNA molecule is largely in individual isolated signifier, dual stranded is

non common. However double stranded is observed in lesion tumours ( works virus ) and

Reovirus ( carnal virus ) .Unlike Deoxyribonucleic acid, RNA is seldom familial in nature and so its chief undertaking is to

carry/simply interpreting the message encoded in DNA into proteins.RNA in most being is

non-genetic in nature ( do non function as familial stuff even the information is presence

in ) .Despite occur largely in non-genetic signifier, it besides occur as familial in nature merely in the

specific system where DNA ( usual familial stuff ) is invariably absent, so RNA map as

familial stuff like DNA. Example in baccy mosaic virus ( Gupta,2001 ) .If RNA is in dual

stranded, the base coupling will be specific as that of DNA.

Structure of RNA

RNA is really similar to DNA, which is made up of four different edifice blocks the

nucleotide. Nucleotide is composed of phosphate, sugar ( ribose ) and base. In this nucleic

acid the bases are purine ( adenine and G ) , which is dual ring and pyrimidine

( U and C ) , which is individual ring. Sugar and phosphate are the anchor. Unlike

Deoxyribonucleic acid, RNA contains hydroxyl group at both C2 and C3 of the ribose ring. It has besides got

uracil base alternatively of thymine.RNA can organize 3-D constructions by coupling of

complementary base within a additive sequence, G pairs with C and A with U organizing

different constructions.Base stacking interaction drama critical function in stabilising the RNA

structure-weak interaction. Phosphodiester bond is besides present and the spiral runs from 5 ‘

a†’3′.The four bases of RNA are given below.

Fig5.Sugar Adenine Guanine Cytosine Uracil

Fig6.Bases of RNA ( Kratz,2009 ) .

Figure 7: Chemical construction of RNA ( Kratz,2009 ) .

Non-genetic RNA synthesis on DNA templet and signifiers three major RNA. They are

differ from one another base on their construction and functional function in the cells. They are

reference be love:

Messenger RNA ( messenger RNA ) -structure

Fig 8.Structure of messenger RNA. ( Synergistic Concepts in Biochemistry, 2002 )

Is chiefly individual stranded and complementary with the sequence of DNA.

It is formed on chromosomes in the nucleole and transported out into the cell

Cytoplasm ( Gupta, 2001 ) .It is heterogenous category of molecules.This messenger RNA nowadayss in additive

Polymers form a codon for the industry of protein since, it is a templet for protein

synthesis. In 5’/N-terminus, methionine, AUG codon act as start/switch on codon and at 3’/C-

end points usually with UAA, UGA, UAG of this three codon map as stop/switch off

codon. Between this two codon ( start and halt ) present a reading frame, where sequencing of

amino occurs. ( Becker,2007 ) .This RNA contribute little mass of the entire RNA nowadays in the

cell. It is less stable, short lived. In bacterial cells messenger RNAs are extremely unstable they are

invariably being degraded and resynthesised but in eucaryotic cells the bend over rate is much

less. ( Conn & A ; Stump, 1976 ) .

Function of messenger RNA related to its construction.

During the nucleuss of written text, messenger RNA is synthesis from the cistron section of Deoxyribonucleic acid

which finally carries familial information contain in DNA into a codon ( three letters

familial codification /triplets ) to ribosome in cytoplasm.The interlingual rendition novices from 5’end

, where codon runs from peculiar switch on codon to exchange off codon at 3’end/ C-

end point of polypeptide concatenation term “ Reading frame ” .Each of the amino acids is encode by one/three codons in this messenger RNA and each codon specifics one amino acid.The start codon like methionine, AUG specified amino acids merely at N-terminus but the three halt codon present at C-terminus did non specified any aminic acids, so interlingual rendition is terminated. The reading frame, which is located in between start and stop codon is remain as uninterrupted codon sequence in

messenger RNA and is translated into a additive sequence of aminic acids in bend synthesis of protein occur.Therefore it served as intermediate between DNA and protein molecule. ( Lehninger,1995 ) .

Transportation RNA ( transfer RNA ) /Soluble RNA ( sRNA )

It is a little polymer RNA species, individual stranded, helica construction, signifier on chromosome and found in cytol located in ribosome ( Conn & A ; Stump, 1976 ) but is independent of ribosome that is charge with an amino acids at one terminal and coated with anticodon at another terminal. This tRNA exist in three degrees:

Fig 9.Secondary construction of transfer RNA. ( Secondary Structure of transfer RNA, n.d. )

1/Primary degree ( additive form ) ,2/.Secondary degree ( stem form ) and 3/.Tertiary construction ( 3-D form ) .All this three transfer RNA portions a common secondary construction and 3-D form. The secondary construction is represented by trefoil foliage form and 3-D resemblance an upside-down ‘L’.They possesses four base brace stems holding three stem loops- a ) anticodon cringle at the underside of secondary construction along with three letters of anticodon, B ) dihydrouracil cringle ( D-loop ) on left side and eventually T loop the sequences of three bases.The above reference anticodon gets pair with mRNA codon, therefore activated amino acids ( the amino acids encoded by mRNA codons ) can added to turning polypeptide molecules.The procedure is specific, it is maintain by aminoacyl-tRNA synthetase enzyme.In this procedure coupling of base in between two RNA normally occurs in 3’base in messenger RNA codon 5’in transfer RNA codon.If the amino acid is so specific to tRNA than right synthesis of ptotein occurs, but if the incorrect amino acid is attached there will be immediate removable of that amino acid out of transfer RNA. ( Lodish, etal,2008 ) .

Function of transfer RNA related to its construction.

The 5 iˆ?-P term end point is ever base paired and it is thought that this contribute to the stableness of the transfer RNA. On the other manus the 3 iˆ? end point ever a four base – individual isolated part and it is the acceptor terminal. ( Freifelter,1986 ) .In this RNA the folded construction promotes its decryption map and modified base assistance in binding of right amino acids. The L-shaped construction extended the length of its base coupling root by stacking them in two sets organizing long base paired part, and so each root are set little due to imperfect aligned.Thus, such aligned provide base paired to stacked on each other and provide stableness ( Weaver,2002 ) .In tRNA the third construction holding anticodon base stack are projecting out off from the anchor of transfer RNA, this places them in place to interact with base of codon in messenger RNA. And distorted nature of anticodon anchor into peculiar spiral form, which facilitates base partner offing with corresponding codons ( Weaver,2002 ) .

RibosomalRNA ( rRNA ) construction.

It exist in individual isolated signifier and most indispensable constituents of of import portion of protein synthesis mechainery are rRNA, ribosome ( existent sites of protein synthesis ) , enzyme etc.It is more stable sort of RNA. This species makes approximately 80 % of entire RNA in the cell. The rRNA is formed from merely a little subdivision of DNA molecule therefore, no definite base relation ship between rRNA and DNA as a hole. Ribosomal RNA has coiling construction which is consequence from turn uping back of a individual isolated polymer at topographic points where H bonding is possible due to short lengths of complementary construction. However, rRNA does non happen as a two-base hit stranded polymer. More over rRNA does non hold highly stiff and stable dual coiling construction of DNA, it may be in several conformations.And this RNA served as of import structural constituents in ribosomes. ( Conn & A ; Stumpf,1976 ) .Three sorts of rRNA found in procaryotes are 16s, 5s and 23s and ribosome are bind to the messenger RNA near to translation get down site. In eukaryotes 18s, 5s and 28s are found and ribosome are bind at 5’end of the messenger RNA ( Conn & A ; Stumpf,1976 ) .

Function of rRNA related to its construction.

It involves in constructing up of ribosomal construction, where the complex construction runs along

the direction of messenger RNA molecule.The ribosome is being adhere to mRNA at 5’end, therefore

look into the suited codon of mRNA.This besides catalyzes the assembly of aminic acids in

polypeptide chains.It even binds with transfer RNA and the accoutrement protein for protein

industries harmonizing to the information nowadays by messenger RNA ( rRNA ) . ( : Lodish,2008 ) .

General maps of RNA

In RNA it contains uracil base, which is non stable as comparison to thymine, so RNA

easy involed in turn uping therefore, consequence in organizing secondary construction ( individual stranded spiral ) .when

it is turn uping, uracil gets brace with A and so stabilized the secondary construction therefore, helps in

smooth flow of familial information in the right sequences of aminic acid during protein

synthesis.It besides prevent the renaturation of spiral due to extremely reactive of U and abscent of

methyl life cell got immediate information ( Weaver,2002 ) . RNA being Ss polymer it

crook /fold back on itself to organize weak bond with another portion of same molecule due its

flexibleness of back bond, so recognized peculiar form base on exact sequence.Than selective

adhering occur, therefore consequence in flow of familial information during protein synthesis.In RNA, OH

group is present on C-2 ‘ which makes chemically laible by hydrolyzing the phosphodiester bond

at impersonal pH.This lead to mononucleotides.OH group besides provide chemical reactive group in

catalysis.Such catalytic functions are play by rRNA in peptide bond formation particularly during

protein synthesis, eventually accurate flow of information ( Lodish,2008 ) . The chief undertaking for RNA stuff is to fabricate the protein through two procedure called written text and interlingual rendition affecting all three types of RNA to make the occupation otherwise but they function hand in glove towards common goal-protein synthesis ( Becker, etal,2007 ) .mRNA carries the familial information from Deoxyribonucleic acid for it orderly and specific sequences of amino to new protein. rRNA serves as structural constituent in ribosome and transfer RNA carry the activated amino acids to stipulate sites on the messenger RNA templet ( Conn & A ; Stumpf,1976 ) .