Covers the whole description of structure of the RNA in detail. Happy learning:)

1. RNA: Structure and it's types
Made by : Anshul Sethi
Roll no : 614/20
Biotech(hons) 1st year

2. Introduction
• Ribonucleic acid is a single-stranded nucleic acid
found in all living cell.
• Just like DNA it is also an information carrier which
contains the information of synthesis of protein.
• RNA molecules perform a variety of roles in the cell
but are mainly involved in the process of protein
synthesis (translation) and its regulation.

3. Occurrence
• In a prokaryotic cell whole of the RNA is found in
the cytoplasm because there is no nucleus.
• In a Eukaryotic cell RNA is mainly found in free in
the cytoplasm and within the ribosomes and also in
the nucleolus.
• It can be also present in mitochondria chloroplast
and in some plant virus and animal virus as a
hereditary material.

4. Structure
• RNA molecule is a single chain of ribonucleotide
arranged in a linear sequence and connected
together by 3'to 5' phosphodiester bonds.
• A ribonucleotide contain three parts

5. • Adenine ,guanine, cytosine and uracil are the
four nitrogen bases present in the RNA
molecule.
• In a RNA the phosphate group at 5' position of
sugar molecule in one ribonucleotide is joined to
the sugar molecule of the next ribonucleotide at
3' position by phosphodiester Bond.
• This forms a backbone of alternating sugar-
phosphate-sugar molecule.
• The nitrogen base molecules are joined to the
sugar molecule at C-1' position of this backbon
by glycosidic Bond.

6. Nucleoside = Nitrogen base + Pentose sugar
Ribonucleoside = Nitrogen base + Ribose sugar

7. Nucleotide is a basic unit of nucleic acid.
Nucleotide=N-base+pentose sugar+ phosphate group
Ribonucleotide=N-base+ribose sugar+phosphate

8. 1.The pentose sugar present
in DNA is deoxyribose.
1.The pentose sugar present
in RNA is ribose.
2.Contain cytosine , thymine
as pyrimidine base and
adenine , guanine as purine
base.
2.Contain cytosine , uracil as
pyrimidine base and adenine
, guanine as purine base.
3.It is a double chain of
polynucleotide.
3.It is a single chain of
polynucleotide.
4.It can replicate itself. 4.It cannot replicate itself.
5.It is genetic material for all
living organisms.
5.It is genetic material for
some plant and animal virus.
6.Mainly occur in the nucleus
as main constituent of
chromosome
6.Mainly occur in cytoplasm and
it is the main constituent of
ribosomes.

10. Genetic RNA
• When RNA acts as a genetic material in an
organism, then it is called Genetic RNA.
• It is only found in plant and animal virus which is
hereditary in the absence of DNA.
• It can be double or single-stranded.
Replication of Genetic RNA
1. Replication of RNA in Retroviruses (Viruses follow
reverse transcription)
ticle enters the host cell,
◆Viruses having RNA as the hereditary material
possess an enzyme called reverse transcriptase.

11. ◆When a virus particle enters the host cell, its RNA
released in the host cytoplasm.
◆ Here, with the help of reverse transcriptase strand of
complementary DNA is synthesised using RNA as
template.
◆This single DNA strand synthesis complementary
antiparallel strand completing the formation of double-
stranded DNA.
◆This viral DNA then joins the DNA of host cell
becoming its integral part.
◆The integrated DNA copy with host DNA is called
provirus DNA and this process of DNA transcription is
called reverse transcription.

12. ◆Utilising synthetic machinery host cell, this DNA
produces several copies of RNA and protein
molecules to be used in the formation of protein
coat.
2. Replication of RNA in RNA-RNA viruses
◆These viruses synthesise new genomic RNA on RNA
template with the help of te enzyme called replicase.
◆These new RNA molecules then synthesise mRNAs
Whiel guide synthesis of viral proteins using host's
ribosomes, tRNA, amino acids and required enzymes.

13. Non genetic RNA
• The organisms which have DNA as their hereditary
material the all types of RNAs present in that
organism are non genetic.
• Cell access the information stored in DNA by
creating RNA to direct the synthesis of proteins by
the process of translation.

14. Messenger RNA or Nuclear RNA
• In 1961 two french scientists Jacob and Monad
hypothesis the existence of a intermediary
between DNA and its product which they named as
mRNA.
• All the genetic information is stored in the DNA so
messenger RNA carries that information from the
DNA of the nucleus to the ribosomes of the
cytoplasm in which the proteins are synthesized on
the basis of this information.
Messanger RNA or Nuclear RNA

15. Characteristics of mRNA
1.It is synthesized as a complementary strand on the
DNA template(3'to5' stand).
2.It contains same complementary base arrangement
of the DNA from which it is copied except that
thymine of DNA is substituted by uracil.
3.In all the Eukaryotic cells the hetrogenous
RNA(hnRNA) is formed first which is a precursor of
the actual mature mRNA.
4.The information present on the Eukaryotic genes
are always in segments .

18. 13.For each polypeptide chain there is only one mRNA is
used.
14.Life span of mRNA in prokaryotes like Bacteria is 2
minutes whereas in eukaryotic mRNA is more stable and
able to survive for hours .

19. Structure of mRNA

20. 1.CAP Region -
◆It is a methylated region made up of 7,methyl guanosine
at 5'end.
◆It provides stability to mRNA
2. Coding Region -
◆It is the region where all the information for protein
chain synthesis is coded.
◆It has generally 1500 nucleotide (depending upon which
protein has to be synthesized.
(a) Initiation codon
◆The coding region always begins with AUG code which
codes for the initiation of the protein synthesis.
◆It codes for methionine amino acid.

21. (b)Stop /Terminating Codon -
◆At the end of coding region UAA or UAG or UGA codon is
present which when read by ribosome the protein synthesis
stops that's why it is known as "Stop" codon.
◆It does not code for any amino acid.
3. Poly-A Tail -
◆It contain polyadenylic acid sequence or poly adenine
nucleotide.
◆It protects the mRNA from degradation.
4. UTR( Untranslated regions ) -
◆Present just after G-Cap .
◆Helps mRNA to bind with ribosomes.
5. NCR( Non coding region) -
◆Present before the Poly-A tail which act as cellular regulator.

22. Tranfer RNA(tRNA)
• Transfer RNA (tRNA) is a small type of stable RNA that
carries an amino acid to the corresponding site of
protein synthesis in the ribosome.
• It is also termed as soluble RNA and it constitute 10-
15% of the total RNA.
Transfer RNA(tRNA)

23. Characteristics of tRNA
1.It is the smallest of all other RNAs having 75-95
nucleotide .
2.The polynucleotide chain of the tRNA has hydroxyl
ion at 3' end and phosphate at 5'end.
3.Due to the internal complementary base pairing,
the polynucleotide chain of the tRNA undergoes
secondary and tertiary folding.
4.as a result tRNA molecule acquires L shape 3D
configuration which resembles twisted cloverleaf.

24. 5.The 3' end of the polynucleotide chain of the tRNA
is called acceptor end as it is the attachment site for
amino acid.
6.In 1965,R.W.Holley proposed cloverleaf model of
tRNA .

25. Cloverleaf model of tRNA

26. Acceptor arm or Amino acid arm

27. Anticodon arm
• It is a loop like structure containing
anticodon sequence nucleotide that
are complementary to triplet codon
of the mRNA molecule.
• It lies opposite to the Amino acid
arm.
• Since the base triplet on mRNA chain
is called codon, its complementary
base triplet on tRNA molecule is
termed as anticodon.
• function of anticodons is to bring
together the correct amino acids to
create a protein, based on the
instructions carried in mRNA.

28. DHU arm (Dihydrouridine arm)
• It has stem formed of 5 base pair and D loop made up
of about 10 nucleotides.
• It contain modified ribonucleotide dihydrouridine in the
D loop derived from uridine.
• The main function of D loop is recognization of amino
acid

29. TΨC Arm or TΨCG arm
• It contains modifed ribonucleotide pseudouridinylate
and ribothymidylate.
• It's stem contains 5 base pairs and terminal loop
contains 7 nitrogenous base with a specific sequence
of T(Ribothymidine),. P(Pseudouridine),C(Cytosine),
G(Guanine).
Variable arm
.It contain 4-21 nucleotide.
•It helps in stability of tRNA.

30. Unusual Base pairs in tRNA
• Addition to the usual bases of RNA( A,U,G,C) there
are some additional unusual base pairs are also
present in tRNA.
• For example :
DHU(Dihydrouridine),T(Ribothymidine),Pseudo
uridine etc.
• Q.what is the role of unusual base pairs?
• Ans-Prevents intramolecular base pairing in the
open tRNA loop.

31. Structures of unusual base pairs

32. Ribosomal RNA (rRNA)
• It is the most common type of RNA found in the
cell.
• It constitutes 70 to 80% of total cellular RNA.
• It is found in ribosomes.
• The rRNA ensures the proper alignment of the
mRNA, tRNA, and the ribosomes.
Structure of rRNA
• It has 3D structure formed by folding
and complementary base pairing.

33. Types of rRNA

34. • In eukaryotes 80s ribosomes are present having
60s as larger ribosomal subunit and 40s as smaller
ribosomal subunit.
• 60s that is larger subunit of the eukaryotic
ribosome is made up of 28s and 5.8s rRNA
molecules.
• 40s that is smaller subunit of the eukaryotic
ribosome is made up of 18s rRNA molecules.
•rRNA is differ in base composition from
tRNA and mRNA.
•rRNA is relatively richer in guanine and
cytosine.
Base composition of rRNA

35. Other types of RNA
1.Small nuclear RNAs(snRNAs)-
◆These are small RNA molecules found in nucleus of
eukaryotic cell.
◆They are formed of 100-215 nucleotide
2.Genetic RNA -
◆In some viruses RNA is genetic material which carries
hereditary information.
3.Enzymatic RNA or Ribozyme -
◆Ribozymes (ribonucleic acid enzymes) are RNA
molecules that have the ability to catalyze specific
biochemical reactions, including RNA splicing

36. Functions of RNA
1.Facilitate the translation of DNA into proteins
2.Functions as an adapter molecule in protein synthesis
3.Serves as a messenger between the DNA and the
ribosomes.
4.Promotes the ribosomes to choose the right amino
acid which is required in building up of new proteins in
the body.
5.It serves as the genetic material in some organisms
(viruses).

37. THANK YOU