1. NUCLEIC ACID
RNA
DNA

2. RNA

3. RNA ( RIBONUCLEIC ACID )
SINGLE STRANDED NUCLEIC ACID.
RNA CONTAINS RIBOSE (HYDROXYL GROUP ATTACHED TO THE PENTOSE RING) .
UNSTABLE GENETIC MATERIAL W.R.T DNA.
COMPLEMENTARY BASE TO ADENINE IS NOT THYMINE AS IT IS IN DNA BUT URACIL.

4. DIFFERENCE BETWEEN DNA & RNA
Double stranded helical nucleic acid.
Complementary base to adenine is thymine.
DNA contains deoxyribose ( no hydroxyl group attached to the pentose ring in the 2` position).
RNA
Single stranded nucleic acid.
Complementary base to adenine is uracil.
RNA contain ribose i.e hydroxyl group attached to the pentose ring in the 2` position.

5. DNA RNA

6. STRUCTURE OF RNA
RNA is a ubiquitous family of macromolecule that perform major vital role in the coding, decoding, regulation and expression of genes. RNA is assembled as a chain of nucleotides. Viruses encode their genetic material using an RNA genome. RNA is a single stranded chain of nucleotide comprise of sugar- phosphate backbone and four nitrogenous base pairs (i.e adenine, uracil, guanine & cytosine) . RNA contains ribose sugar. A phosphate group is attached to the 3` position of one ribose and 5` position of next. Bases form hydrogen bonds b/w C-G & A-U. Structural feature of RNA that distinguish it from DNA is the presence of a hydroxyl group at the 2` position of ribose sugar. RNA is unstable in nature due to 2` OH group, presence of uracil and its catalytic behaviour.

8. TYPES OF RNA mRNA ( messenger RNA). rRNA ( ribosomal RNA ).
tRNA ( transfer RNA ).
tmRNA ( transfer messenger RNA).
snRNA or introns ( small nuclear RNAs).
PiRNA ( piwi-interacting RNAs).
dsRNA ( double stranded RNA).
tasiRNA ( trans-acting siRNA).

9. LIST OF RNAs IN NATURE TYPE mRNA rRNA tRNA snoRNA FUNCTION
Codes for protein.
structural & catalytic role during translation.
translation. (brings aminoacids & reads the genetic code).
Nucleotide modification of RNAs.

10. LIST OF RNA TYPES FUNCTION Sm Y RNA snRNA SRP RNA Rnase MRP
Telomerase RNA
miRNA
piRNA
Satellite RNA
mRNA trans – splicing.
splicing & other function.
membrane integration.
rRNA maturation & DNA replication.
telomere synthesis.
gene regulation.
transposon defence.
self propogating.

12. mRNA

13. mRNA CODON CHART

14. mRNA PROCESSING

15. Messenger RNA is a large family of RNA molecule that convey genetic information from DNA to the ribosome , where they specify the amino acid sequence of the protein products of gene expression . Following transcription of mRNA by RNA polymerase , the mRNA is translated into a polymer of amino acid . mRNA genetic information is encoded in the sequence of nucleotides , which are arranged into codons consisting of three bases.

16. Each codon encodes for a specific amino acid , except the stop codons which terminate the protein synthesis .This process of translation of codon into amino acids requires two other types of RNA : tRNA that mediates recognition of codon & provides the corresponding amino acid and rRNA that is central component of the ribosomes protein –manufacturing machinery .

17. During transcription,RNA polymerase makes a copy of a gene from the DNA to mRNA as needed.The short lived unprocessed product is termed precursor mRNA.Eukaryotic pre mRNA requires extensive processing. 5' cap addition : A 5' cap (also termed an RNA cap, an RNA 7-methylguanosine cap) is a modified guanine nucleotide that has been added to the "front" or 5' end of a mRNA after the start of transcription. The 5' cap consists of a terminal 7-methylguanosine residue.Shortly after the start of transcription, the 5' end of the mRNA being synthesized is bound by a cap-synthesizing complex associated with RNA polymerase. This enzymatic complex catalyzes the chemical reactions that are required for mRNA capping.

18. Splicing is the process by which pre-mRNA is modified to remove certain stretches of non –coding sequences called introns ; the stretches that remain include protein -coding sequences and are called exons . Sometimes pre -mRNA messages may be spliced in several different ways , allowing a single gene to encode multiple proteins . This process is called alternative splicing . Splicing is usually performed by an RNA -protein complex called the spliceosome , but some RNA molecules are also capable of catalyzing their own splicing ( see ribozymes ).

19. Polyadenylation is the covalent linkage of a polyadenylyl moiety to a messenger RNA molecule. In eukaryotic organisms , with the exception of histones , all messenger RNA (mRNA) molecules are polyadenylated at the 3' end . The poly (A) tail and the protein bound to it aid in protecting mRNA from degradation by exonucleases . Polyadenylation is also important for transcription termination .

20. RIBOSOMAL RNA

22. Ribosomal ribonucleic acid (rRNA) is the RNA component of the ribosome, and is essential for protein synthesis in all living organisms. It composes the predominant material within the ribosome, which is ca. 60% rRNA and 40% protein by weight. Ribosomes contain two major rRNAs and 50 or more proteins.The LSU rRNA acts as a ribozyme, catalyzing peptide bond formation. The ribosomal RNAs form two subunits, the large subunit (LSU) and small subunit (SSU).

23. mRNA is sandwiched between the small and large subunits, and the ribosome catalyzes the formation of a peptide bond between the 2 amino acids. A ribosome also has 3 binding sites called A, P, and E. The A site in the ribosome binds to an aminoacyl-tRNA (a tRNA bound to an amino acid).

24. The amino (NH2) group of the aminoacyl-tRNA, which contains the new amino acid, attacks the ester linkage of peptidyl-tRNA (contained within the P site), which contains the last amino acid of the growing chain, forming a new peptide bond. This reaction is catalyzed by peptidyl transferase . prokaryotic and eukaryotic ribosomes can be broken down into two subunits (the S in 16S represents Svedberg units), nt= length in nucleotides of the respective rRNAs. Prokaryotic = Both 70S 50S (5S : 120 nt, 23S  : 2906 nt) 30S (16S : 1542 nt) eukaryotic = 80S 60S (5S : 121 nt,[1] 5.8S : 156 nt,[2] 28S : 5070) 40S (18S : 1869 nt)

25. Eukaryotes generally have many copies of the rRNA genes organized in tandem repeats; in humans approximately 300–400 repeats are present in five clusters (on chromosomes 13, 14, 15, 21 and 22). Because of their special structure and transcription behaviour, rRNA gene clusters are commonly called "ribosomal DNA”. The 18S rRNA in most eukaryotes is in the small ribosomal subunit, and the large subunit contains three rRNA species (the 5S, 5.8S and 28S in mammals, 25S in plants, rRNAs).

26. Mammalian cells have 2 mitochondrial (12S and 16S) rRNA molecules and 4 types of cytoplasmic rRNA (the 28S, 5.8S, 18S, and 5S subunits). The 28S, 5.8S, and 18S rRNAs are encoded by a single transcription unit (45S) separated by 2 internally transcribed spacers. The 45S rDNA organized into 5 clusters (each has repeats) on chromosomes 13, 14, 15, 21, and 22. These are transcribed by RNA polymerase I. Translation is the net effect of proteins being synthesized by ribosomes, from a copy (mRNA) of the DNA template in the nucleus.

27. TRANSFER RNA

28. A tRNA is an adaptor molecule composed of RNA, typically to 94 nucleotides in length, that serves as the physical link between the nucleotide sequence of nucleic acids (DNA and RNA) and the amino acid sequence of proteins . It does this by carrying an amino acid to the protein synthetic machinery of a cell (ribosome) as directed by a three –nucleotide sequence (codon) in a messenger RNA (mRNA) . As such , tRNAs are a necessary component of protein translation , the biological synthesis of new proteins according to the genetic code .

29. The specific nucleotide sequence of an mRNA specifies which amino acids are incorporated into the protein product of the gene from which the mRNA is transcribed , and the role of t RNA is to specify which sequence from the genetic code corresponds to which amino acid . One end of the tRNA matches the genetic code in a three- nucleotide sequence called the anticodon . The anticodon forms three base pairs with a codon in mRNA during protein biosynthesis .

30. The covalent attachment to the tRNA 3’ end is catalyzed by enzymes called aminoacyl-tRNA synthetases . During protein synthesis , tRNAs with attached amino acids are delivered to the ribosome by proteins called elongation factors which aid in decoding the mRNA codon sequence . If the tRNA 's anticodon matches the mRNA , another tRNA already bound to the ribosome transfers the growing polypeptide chain from its 3 ’ end to the amino acid attached to the 3 ’ end of the newly delivered tRNA , a reaction catalyzed by the ribosome.

31. The cloverleaf structure becomes the 3D L-shaped structure through coaxial stacking of the helices, which is a common RNA Tertiary Structure motif. The 5'-terminal phosphate group. The acceptor stem is a 7-base pair stem made by the base pairing of the 5'-terminal nucleotide with the 3'-terminal nucleotide (which contains the CCA 3'-terminal group used to attach the amino acid). The CCA tail is a cytosine-cytosine-adenine sequence at the 3' end of the tRNA molecule. This sequence is important for the recognition of tRNA by enzymes and critical in translation. The D arm is a 4 bp stem ending in a loop that often contains dihydrouridine. The anticodon arm is a 5-bp stem whose loop contains the anticodon. The T arm is a 5 bp stem containing the sequence TΨC where Ψ is a pseudouridine.

32. An anticodon is a unit made up of three nucleotides that correspond to the three bases of the codon on the mRNA. Each tRNA contains a specific anticodon triplet sequence that can base -pair to one or more codons for an amino acid . Some anticodons can pair with more than one codon due to a phenomenon known as wobble base pairing . To provide a one –to -one correspondence between tRNA molecules and codons that specify amino acids , types of tRNA molecules would be required per cell . Aminoacylation is the process of adding an aminoacyl group to a compound . It produces tRNA molecules with their CCA 3‘ ends covalently linked to an amino acid . Each tRNA is aminoacylated (or charged ) with a specific amino acid by an aminoacyl tRNA synthetase . There is normally a single aminoacyl tRNA synthetase for each amino acid .

33. FUNCTION OF mRNA
IT CONVEY GENETIC INFORMATION FROM DNA TO THE RIBOSOMES , WHERE THEY SPECIFY THE AMINO ACIDS SEQUENCES OF PROTEINS PRODUCTS OF GENE
EXPRESSION.FOLLOWING TRANSCRIPTION OF mrna BY RNA POLYMERASE , THE mRNA IS TRANSLATED INTO A POLYMER OF AMINO ACID.INFORMATION IN DNA CANNOT BE DIRECTLY DECODED INTO PROTEINS, IT IS FIRST TRANSCRIBED OR COPIED INTO mRNA.

34. FUNCTION OF tRNA
TRANSFER RNA FUNCTION AS AN INTERPRETER BETWEEN NUCLEIC ACID & PROTEIN LANGUAGE BY PICKING UP SPECIFIC AMINO ACIDS AND RECOGNIZING THE APPROPRIATE CODON IN THE MRNA .ITS MAIN FUNCTION IS TO TRANSFER AMINO ACIDS TO GROWING POLYPEPTIDE CHAIN DURING THE RIBOSOMAL SITE OF PROTEIN SYNTHESIS DURING TRANSLATION.

35. FUNCTION OF rRNA
RIBOSOMAL RNA FORMS PART OF RNA ,WHICH ARE INVOLVED IN PROTEIN SYNTHESIS.THE CATALYTIC ACTIVITY OF THE RIBOSOME -THE CREATION OF A CHEMICAL BOND BETWEEN TWO AMINO ACIDS I.E PEPTIDE BOND COMES FROM THE RNA COMPONENT OF RIBOSOME.