RNA by Puja Ghosh

1. Basic study on Ribonucleic
Acid(RNA)
Presented By Puja Ghosh
M.Pharm 1st year,
Pharmacognosy

2. . Nucleic acid
• Essential biopolymers.
• Composed of nucleotides.
• composed of a phosphate-deoxyribose sugar and
nitrogenous bases A,G,C,T,U.
DNA
• Sugar is derived from ribose as deoxyribose
• alternating sugar-phosphate backbone
• contains our unique genetic code
• Two strands are held by hydrogen bonds,
A-T, G-C.
RNA
• Sugar is a compound ribose.
• Essential for synthesis of proteins.
• Nucleotides are held together by
phosphodiester linkage.
• Single stranded molecule, G-C, A-U.
• Essential in coding and decoding of
genes

3. • .
Nucleotide
• Long thread-like monomers that make up nucleic acids
Nitrogenous base (A, C, G, T or
U)
Pentose sugar
a 5-carbon sugar
Phosphate
Purines Pyrimidines
Cytosine (C) Thymine (T) Uracil (U).
Adenine (A) Guanine (G)

4. •The Central Dogma of Molecular Biology states
that DNA makes RNA makes proteins.
• The process by which DNA is copied to RNA is called transcription, and that by
which RNA is used to produce proteins is called translation.

5. •DNA REPLICATION
• Each time a cell divides, each of its double
strands of DNA splits into two single
strands.
• Each of these single strands acts as a
template for a new strand of
complementary DNA.
• As a result, each new cell has its own
complete genome. This process is known
as DNA replication.
Initiation The splitting happens in places of the chains
which are rich in A-T. unzip’ the double helix structure of
the DNAmolecule, formed Replication “Fork”
Elongation By this process DNA polymerases are
responsible creating the new strand.
Termination After the continuous and discontinuous
strands are formed, enzyme exonuclease removes all RNA
primers from the original strands by the help of DNA ligase.

6. • DNA REPLICATION: The process by which DNA makes itself copy during cell division.
‘unzip’ the double helix structure of the DNA molecule
Single strands of DNA creates a ‘Y’ shape called a replication ‘fork’
leading strand oriented in the 3’ to 5’ direction (towards the replication fork)
lagging strand oriented in the 5’ to 3’ direction (away from replication fork)
Continuous replication
Bases are matched up (A-T, C-G)
Adding bases A, C, G, T to the leading strand of DNA in the 5’ to 3’ direction.
New DNA automatically winds up into a double helix.
Helicase enzyme breaks
hydrogen bond
Primer: A short
piece of RNA
Produced by an
enzyme primase
Discontinuous replication
Okazaki
fragments will
need to be
joined up later
Lagging strand is
copied in short
bursts of about 1000
bases, called Okazaki
fragments.
Enzyme Exonuclease strips removes away the primers
Primers are filled by complementary nucleotides.
Proofread to make sure there are no mistakes in the
new DNA sequence by DNA polymerases .
DNA ligase seals up the sequence of DNA into two
continuous double strands.
Two DNA molecules consisting of one new and one old
chain of nucleotides.

7. • .
RNA
Messenger RNA (mRNA) Transfer RNA (tRNA)
Ribosomal RNA
(rRNA)

8. Messenger RNA
(mRNA)
• Formed in transcription.
• Transported out of the nucleus
into the cytoplasm, to the
ribosome (the cell's protein
synthesis factory).
• Directs protein synthesis.
• Convey genetic information
from DNA to the ribosome.
• carries the information needed
for protein synthesis.

9. •Formation of pre-messenger RNApartial unwinding of the double helix must occur before transcription
can take place
only one strand is transcribed, contains gene, called sense strand
copy of the sense strand, antisense strand that is transcribed.
Ribonucleotide triphosphates (NTPs) align along the antisense DNA
strand
A pairs with U
RNA polymerase joins the ribonucleotides, to form a pre-messenger
RNA molecule
Transcription ends when RNA polymerase enzyme reaches a triplet of
bases
RNA polymerase enzymes
that catalyze the process
a pre-messenger RNA
molecule
DNA molecule re-winds to
re-form the double helix.

10. • RNA Splicing:
• Spliceosomes are multimegadalton RNA (protein complexes) responsible for the
faithful removal of noncoding segments (introns which are not required for
protein synthesis) from pre-messenger RNAs (pre-mRNAs), for the maturation of
eukaryotic mRNAs, this process called RNA splicing.
• Introns are spliced from the pre-messenger RNA to give messenger RNA (mRNA).

11. •tRNA Messenger RNA is not directly
involved in protein synthesis − transfer RNA
(tRNA) is required for this Protein synthesis.
Each tRNA contains one Anticodon, corresponds to one
mRNA codon and one amino acids
correct tRNA Anticodon finds the mRNA, its amino acid is
added to the growing protein chain.
After adding amino acid to the growing protein chain, a
peptide bond forms between the two amino acids to make
a tripeptide;
After this tRNA goes to pick up a new amino acid to bring
to a new mRNA.
the unchanged tRNA leaves ribosome

12. •rRNA:
• 3/5 of ribosome mass.
• Ribosomal RNA(rRNA),
that is the central
component of the
ribosome's protein-
manufacturing machinery.
• Proteins and rRNAs, come
together to form a
molecular machine that
can read messenger RNAs
and translate the
information they carry into
proteins and provide space
for protein synthesis.
rRNA(70s, 80s)
Small subunit (SSU)
• eukaryotic - 30s
• Prokaryotic - 40s
large subunit (LSU)
• acts as a ribozyme,
catalyzing peptide bond formation.
• eukaryotic - 50s
• Prokaryotic - 60s
rRNA in dark blue (small subunit) and dark red (large subunit). Lighter colors represent ribosomal proteins.

13. •Importance of RNA:
• mRNA: carries genetic formation of DNA for protein synthesis from
nucleus to Ribosome in the genetic code.
• it is important because ribosome can not reach to the DNA inside the
cell nucleus.
• tRNA: Carries amino acids and drop it to a particular position by
recognizing codon with the help of Anticodon.
• brings amino acid for protein production.
• rRNA: Combines with proteins to form Ribosome.
• protein builder.

14. • Structure of DNA and RNA

15. Differences between RNA and DNA
DNA RNA
Double stranded Single stranded
The sugar moiety is deoxy ribose Ribose is the main sugar
Pyrimidine components differ. uracil is
never found
Pyrimidine components differ. Thymine
is never found(Except tRNA)
Mainly found in nucleus Mainly cytoplasmic, but also present in
nucleus.
DNA can form DNA by replication, RNA is synthesized from DNA, it can not
form DNA

16. THANK YOU