2. • Functional RNA molecule that does not
code for proteins
• The DNA sequence from which a
functional non-coding RNA is
transcribed is often called an RNA
gene.
FUNCTIONS :
Regulating gene expression
Regulating protein synthesis
Cell growth and differentiation
NON CODING RNAs (ncRNA)
3. Housekeeping non-coding RNAs are
constitutively expressed and mostly
involved in RNA splicing regulation,
rRNA modification and required for
the maintenance of basic cellular
function.
Regulatory non-coding RNAs play
crucial role in regulating gene
expression and influencing cellular
functions and responses.
4. RIBOSOMAL RNA
(rRNA)
• Found in ribosomes
• Most stable type of RNA
• 80 % of the total cellular
RNA
• 60-80% of the weight of
the ribosome is made up
of ribosomal RNA
6. TRANSFER RNA
(tRNA)
• Adaptor molecule composed of RNA
• 76 to 90 nucleotides in length
• Provides physical link between
the genetic code in mRNA and
the amino acid sequence of proteins
SECONDARY STRUCTURE - Cloverleaf
structure
TERTIARY STRUCTURE -
L-shaped 3D
structure
8. MICRO RNA
(miRNA) Small, single-stranded, non-
coding RNA molecules
containing 21–23 nucleotides.
Found in plants, animals, and even some
viruses
9. miRNAs are involved in RNA silencing and
post-transcriptional regulation of gene
expression
miRNAs play a central role in cell
differentiation, proliferation, and
survival.
They silence the mRNA molecules by one
or more of the following processes:
•Cleaving the mRNA strand into two pieces.
•Destabilizing the mRNA by shortening
its poly(A) tail.
•Reducing translation of the mRNA into
proteins.
10. Small Nuclear RNA (snRNA)
• SnRNAs are about 150 nucleotides long.
• They are found in the cell nucleus in splicing
speckles and Cajal bodies.
• They are transcribed by RNA polymerase II or
RNA polymerase III
• Always associated with a set of specific proteins,
and the complexes are referred to as small
nuclear ribonucleoproteins
11. SnRNAs are a key component of the
spliceosome, which removes introns
from pre-mRNA to create mature
mRNA.
They also help regulate gene expression
and nuclear maturation of mRNA
transcripts.
SnRNPs recognize splice sites and branch sites in introns through base-pairing
interactions with pre-mRNA. This allows the spliceosome to form and catalyze the
splicing of pre-mRNA.
