Nucleic acids are polymers of nucleotides that include DNA and RNA, which are found in living systems. RNA is one of the major biological macromolecules essential for life, along with DNA and proteins. There are different types of RNA including mRNA, tRNA, and rRNA that have primary functions like translation, protein synthesis, and mRNA processing. RNA can also carry genetic information like DNA and some viruses have RNA genomes.

1. Lini Cleetus C
1st M.Sc BPS
CBPST, KOCHI

2. What we will be discussing?
Nucleic acids
Nucleotides
Nucleoside
Nitrogenous bases
Pentose sugar
DNA and RNA
RNA
Introduction
Different types &
functions
Conclusion

3. Nucleic Acids
Nucleic acids are
polymers of
nucleotides
They include
DNA(deoxyribonucle
ic acid) and
RNA(ribonucleic
acid);
-which are found in
living systems
RNA

4. Nucleotide
PURINES PYRIMIDINES RIBOSE DEOXYRIBOSE
NITROGENOUS PENTOSE PHOSPHATE
BASES SUGAR GROUP

5. Nucleosides
A nitrogenous base(purine or pyrimidine) bound to a
pentose sugar(ribose or deoxyribose)
Example:
adenosine or deoxyadenosine
Guanosine or deoxyadenosine
Cytidine or deoxycytidine
Uridine or deoxythymidine

6. Nitrogenous bases
Cytosine(C) Thymine(T) Uracil(U)
Adenine(A) Guanine(G)
Pyrimidines
Purines

7. Pentose sugars

8. PRIMARY STRUCTURE OF
NUCLEIC ACIDS
N-Glycosidic
linkages

9. Structure of nucleic acids
Back bone is sugar and phosphate group
Nitrogenous bases linked to sugar moiety project from
the backbone
Nitrogenous bases are linked to pentose sugar through
N-glycosidic linkage to form a nucleoside
Phosphate group is linked with 3’OH of nucleoside
through phosphoester linkage
2 nucleotides are linked through 3’-5’-phosphodiester
linkage to form a dinucleotide

10. More and more such groups will be linked to form a poly
nucleotide chain
Such a polymer has a free phosphate moiety at 5’ end of
ribose sugar and it is called as 5’-end of polynucleotide chain
At other end, ribose has free 3’-OH group which is called
as the 3’-end of polynucleotide chain
In RNA, every nucleotide has an additional-OH present at
2’-position of ribose

11. DNA and RNA

12. DNA and RNA
DNA contains the sugar deoxyribose, while RNA contains the sugar
ribose
DNA is a double stranded molecule while RNA is a single stranded
molecule
DNA is stable under alkaline conditions while RNA is not stable
DNA and RNA perform different functions in humans. DNA is
responsible for storing and transferring genetic information while RNA
directly codes for amino acids and as acts as a messenger between DNA
and ribosomes to make proteins
DNA and RNA base pairing is slightly different, since DNA uses the bases
adenine, thymine, cytosine, and guanine; RNA uses adenine, uracil,
cytosine, and guanine. Uracil differs from thymine in that it lacks a methyl
group on its ring

13. Ribonucleic acid
Ribonucleic acid, or RNA is one of
the major biological macromolecules
that are essential for all known forms
of life (along with DNA and proteins)
 Each nucleotide in RNA contains
a ribose sugar, with carbons
numbered 1' through 5'. A base is
attached to the 1' position, in general,
adenine (A), cytosine (C),
guanine(G), and uracil (U).

14. Structure of RNA

15. Synthesis
Synthesis of RNA is usually catalyzed by an enzyme—
RNA polymerase
By using DNA as a template
The process is known as transcription
There are also a number of RNA-dependent RNA
polymerases that use RNA as their template for synthesis
of a new strand of RNA
A number of RNA viruses (such as poliovirus) use this
type of enzyme to replicate their genetic material

16. Types of RNA
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
Messenger RNA (mRNA)

17. Messenger RNA (mRNA)
 Messenger RNA (mRNA) carries information about a
protein sequence to the ribosomes, the protein
synthesis factories in the cell
 It is coded so that every three nucleotides (a codon)
correspond to one amino acid
 . In eukaryotic cells, once precursor mRNA (pre-
mRNA) has been transcribed from DNA, it is
processed to mature mRNA
 This removes its introns—non-coding sections of the
pre-mRNA
 The mRNA is then exported from the nucleus to the
cytoplasm, where it is bound to ribosomes
and translated into its corresponding protein form
with the help of tRNA

18. Transfer RNA (tRNA)
Transfer RNA (tRNA) is a small RNA
chain of about 80 nucleotides
 It transfers a specific amino acid to a
growing polypeptide chain at the
ribosomal site of protein synthesis during
translation
 It has sites for amino acid attachment
and an anticodon region
for codon recognition that binds to a
specific sequence on the messenger RNA
chain through hydrogen bonding

19. Ribosomal RNA (rRNA)
Ribosomal RNA (rRNA) is the catalytic
component of the ribosomes
 Eukaryotic ribosomes contain four different
rRNA molecules: 18S, 5.8S, 28S and 5S rRNA
 Three of the rRNA molecules are synthesized
in the nucleolus, and one is synthesized elsewher
. In the cytoplasm, ribosomal RNA and protein
combine to form a nucleoprotein called a
ribosome
 The ribosome binds mRNA and carries out
protein synthesis
 Several ribosomes may be attached to a single
mRNA at any time.
Nearly all the RNA found in a typical
eukaryotic cell is rRNA.

20. D Dobbs ISU - BCB 444/544X:
RNA Structure Prediction
RNA types & functions
Types of RNAs Primary Function(s)
mRNA - messenger translation (protein synthesis)
regulatory
rRNA - ribosomal translation (protein synthesis) <catalytic>
t-RNA - transfer translation (protein synthesis)
hnRNA - heterogeneous nuclear precursors & intermediates of mature
mRNAs & other RNAs
scRNA - small cytoplasmic signal recognition particle (SRP)
tRNA processing <catalytic>
snRNA - small nuclear
snoRNA - small nucleolar
mRNA processing, poly A addition <catalytic>
rRNA processing/maturation/methylation
regulatory RNAs (siRNA,
miRNA, etc.)
regulation of transcription and translation,
L Samaraweera 2005

21. RNA genomes
Like DNA, RNA can carry genetic
information. RNA viruses have genomes composed
of RNA that encodes a number of proteins. The
viral genome is replicated by some of those
proteins, while other proteins protect the genome as
the virus particle moves to a new host cell.

22. Double-stranded RNA
Double-stranded RNA (dsRNA) is RNA with two
complementary strands, similar to the DNA found
in all cells. dsRNA forms the genetic material of
some viruses (double-stranded RNA viruses)

23. Double-stranded RNA

24. Conclusion
RNA is one of the major biological
macromolecule essential in all life forms
Ribose is the sugar unit present in it
Guanine ,adenine, uracil and cytisine are the
nitrogenous bases present in RNA
There are different types of RNA:- mRNA,
tRNA, Rrna
Like DNA,RNA also can behave as a genetic
material