Types of RNA and their Functions

1. Assignment no:3 of
Molecularbiology
Topic:Types of RNA And Their Functions
Submitted to:
Muhammad Owais
Submitted by:
Rameen Iqbal
Registration No:
L1F18BSBT0053
Section: B
Table of Contents
Definition:..........................................................................................................................................................................................................................3
History of RNA:.................................................................................................................................................................................................................3
RNA STRUCTURE:.............................................................................................................................................................................................................4
OVERVIEW:..............................................................................................................................................................................................................4
Different Types of RNA Have the Same Basic Structure:..........................................................................................................................................4

2. RNA Assembly Is Unidirectional:...................................................................................................................................................................................6
RNA Can Form Secondary Structures:..........................................................................................................................................................................6
The Secondary and Tertiary Structure of tRNA Enables Protein Synthesis:..........................................................................................................7
RNA FUNCTION: ...............................................................................................................................................................................................................7
Types of RNA and their Functions.................................................................................................................................................................................9
Types of RNA: ...................................................................................................................................................................................................................9
I. Ribosomal RNA ...........................................................................................................................................................................................................9
II. Transfer RNA...............................................................................................................................................................................................................9
III. Small nuclear RNA...................................................................................................................................................................................................9
IV. Guide RNA..................................................................................................................................................................................................................9
V. Small Regulatory RNA ..............................................................................................................................................................................................9
VI. Antisense RNA...........................................................................................................................................................................................................9
VII. Housekeeping RNA ................................................................................................................................................................................................9
Function of Ribosomal RNA: ..........................................................................................................................................................................................9
Small nuclear RNA: ........................................................................................................................................................................................................11
Guide RNA:......................................................................................................................................................................................................................12
Antisense RNAs ..............................................................................................................................................................................................................13
Small Regulatory RNAs..................................................................................................................................................................................................13
House-keeping RNAs .....................................................................................................................................................................................................13
References: .....................................................................................................................................................................................................................14

3. Introduction of RNA (Structure and Nature)
Definition:
RNA or ribonucleic destructive is a polymer of nucleotides that is included a ribose sugar, a phosphate, and
bases, for instance, adenine, guanine, cytosine, and uracil. It expects a fundamental activity in quality
enunciation by going about as the somewhere between the inherited information encoded by DNA and proteins.
As seen in diagram below:
RNA has a structure fundamentallythe same asthat of DNA.The keydistinctioninRNA structure isthatthe ribose sugar
inRNA hasa hydroxyl (- OH) bunchthat ismissinginDNA.
History of RNA:
Nucleic acids were first discovered by Friedrich Miescher in 1868 who called the material as
‘nuclei’ as it was found in the nucleus and this led to the discovery of RNA. The key milestone in
the history of RNA is given below,
 In the year 1939, the role of DNA in protein synthesis was postulated.
 In the year 1959 Severo Ochoa won the Nobel prize for discovering the RNA synthesis mechanism.
 In the year 1965, Robert W. Holley sequences 77 nucleotides of yeast tRNA.

4. Some of the highlights of RNA molecules are given below,
 RNA was distinctly different from DNA because of its sensitivity towards alkaline –OH group on the
ribose.
 ATP and GTP were to be the main energy source and building blocks for RNA.
 Adenine, cytosine and guanine were the three bases common to RNA and DNA while instead of
thymine Uracil is present into the RNA.
RNA STRUCTURE:
OVERVIEW:
The basic structure of RNA includes a five-carbon sugar and one of four nitrogenous bases. But most RNA is
single-relinquished, it can shape complex discretionary and tertiary structures. Such structures accept basic
occupations in the rule of translation and understanding.
Different Types of RNA Have the Same Basic Structure:
There are three essential sorts of ribonucleic destructive (RNA): messenger RNA (mRNA), move RNA (tRNA),
and ribosomal RNA (rRNA). All of the three RNA types contain a single deserted chain of nucleotides. Each
nucleotide is made out of the five-carbon sugar ribose. The carbon particles of ribose are numbered one through
five. Carbon number five passes on a phosphate social occasion and carbon number one a nitrogenous base.
As shown below:
There are four nitrogenous bases in RNA—adenine (A), guanine (G), cytosine (C), and uracil (U). Uracil is the
fundamental base in RNA that is missing in DNA, which uses thymine (T. During interpretation, RNA is mixed

5. from a DNA design reliant on correlative legitimate of the new RNA bases to the DNA bases; A connections to
T, G binds to C, C binds to G, and U binds to A.
As shown in below fig:
Even though RNA is single stranded, most types of RNA molecules show extensive intramolecular base pairing
between complementary sequences within the RNA strand, creating a predictable three-dimensional structure
essential for their function, as shown in below figure:
(a) Ribonucleotides contain the pentose sugar ribose instead of the deoxyribose found in deoxyribonucleotides.
(b) RNA contains the pyrimidine uracil in place of thymine found in DNA.

6. RNA Assembly Is Unidirectional:
Like DNA, abutting nucleotides in RNA are associated together through phosphodiester bonds. These bonds
structure between the phosphate social event of one nucleotide and a hydroxyl (– OH) pack on the ribose of the
touching nucleotide.
This structure advances RNA its directionality—that is, the two pieces of the deals of nucleotides are
remarkable. Carbon number five of ribose passes on an unbound phosphate pack which offers rise to the name
5' end (read five prime). The last ribose at the contrary completion of the nucleotide chain has a free hydroxyl (–
OH) bundle at carbon number 3; subsequently, this completion of the RNA molecule is called 3' end. As
nucleotides are added to the chain during translation, the 5' phosphate social event of the new nucleotide reacts
with the 3' hydroxyl get-together of the creating chain. Thusly, RNA is continually accumulated in the 5' to 3'
course.
RNA Can Form Secondary Structures:
Discretionary structures are confined by indispensable base coordinating between far away nucleotides on a
comparable single-relinquished RNA. Fasten circles are surrounded by relating coordinating of bases inside 5-
10 nucleotides of each other. Stem-circles are encircled by coordinating of bases that are secluded by 50 to
numerous nucleotides. In prokaryotes, these discretionary structures function as transcriptional controllers. For
instance, a catch circle can fill in as an end sign with the ultimate objective that when understanding impetuses
experience this structure, they detach from the mRNA and interpretation stops. Stem-circles or clasp hovers at
the 3' or 5' closes in like manner control mRNA quality in eukaryotes by hindering the definitive of
ribonucleases—exacerbates that degenerate RNA.
Below the secondary structure of RNA.
Discretionary structures can outline progressively jumbled tertiary structures called pseudoknots. Pseudoknots
are surrounded when bases ok locale of assistant structures speak with comparing bases outside the circle.
These tertiary structures expect key employments in RNA structure and limit.

7. The Secondary and Tertiary Structure of tRNA Enables Protein Synthesis:
tRNAs fill in as connector iotas during the translation of mRNA into proteins. Toward one side, tRNAs pass on
an amino destructive. At the far edge, they bind to a mRNA codon—a course of action of three nucleotides that
encodes a specific amino destructive. tRNA particles are regularly 70-80 nucleotides long and overlay into a
stem-circle structure that takes after a cloverleaf. Three of the four stems have circles containing 7-8 bases. The
fourth stem is unlopped and fuses the free 5' and 3' portions of the deals strand. The 3' end goes about as the
amino destructive acceptor site.
The three-dimensional structure of tRNA is L-framed, with the amino destructive confining site toward one side
and an anticodon at the furthest edge. Anticodons are groupings of three nucleotides that are relating to the
mRNA codon. This whimsical condition of the tRNA engages it to bind to ribosomes, where protein
amalgamation occurs.
RNA FUNCTION:
Cells get to the information set aside in DNA by making RNA to organize the mix of proteins through the
method of understanding. Proteins inside a cell have various limits, including building cell structures and filling
in as compound driving forces for cell manufactured reactions that give cells their specific traits. The three
standard sorts of RNA truly connected with protein mix are banner carrier RNA (mRNA), ribosomal RNA
(rRNA), and move RNA (tRNA).
In 1961, French specialists François Jacob and Jacques Monod guessed the nearness of a center individual
among DNA and its protein things, which they called conveyance individual RNA.16 Evidence supporting their
hypothesis was aggregated soon a brief timeframe later exhibiting that information from DNA is transmitted to
the ribosome for protein blend using mRNA. In case DNA fills in as the absolute library of cell information,
mRNA fills in as a duplicate of unequivocal information required at a point in time that fills in as the rules to
make a protein.
The mRNA passes on the message from the DNA, which controls the aggregate of the cell practices in a cell. If
a cell requires a protein to be organized, the quality for this thing is "turned on" and the mRNA is consolidated
through the method of translation. The mRNA by then speaks with ribosomes and other cell equipment to
organize the amalgamation of the protein it encodes during the methodology of translation (see Protein
Synthesis). mRNA is commonly unsafe and temporary in the telephone, especially in prokaryotic cells, ensuring
that proteins are potentially made when required.
In below fig you will see: A generalized illustration of how mRNA and tRNA are used in protein synthesis
within a cell.
rRNA and tRNA are consistent sorts of RNA. In prokaryotes and eukaryotes, tRNA and rRNA are encoded in
the DNA, by then copied into long RNA particles that are cut to release more diminutive pieces containing the
individual create RNA species. In eukaryotes, association, cutting, and get together of rRNA into ribosomes

8. occurs in the nucleolus zone of the center, yet these activities occur in the cytoplasm of prokaryotes. Neither of
these sorts of RNA passes on rules to organize the association of a polypeptide, yet they accept other critical
employments in protein blend.
Ribosomes are made out of rRNA and protein. As its name suggests, rRNA is a critical constituent of
ribosomes, making up to about 60% of the ribosome by mass and giving the territory where the mRNA ties. The
rRNA ensures the most ideal course of action of the mRNA, tRNA, and the ribosomes; the rRNA of the
ribosome also has an enzymatic activity (peptidyl transferase) and catalyzes the advancement of the peptide
bonds between two balanced amino acids during protein association.
Despite the way that rRNA had for a long while been thought to serve essentially a helper work, its reactant
work inside the ribosome was exhibited in 2000.17 Scientists in the exploration places of Thomas Steitz (1940–
) and Peter Moore (1939–) at Yale University had the alternative to come to fruition the ribosome structure from
Haloarcula marismortui, a halophilic archaeon isolated from the Dead Sea. Taking into account the importance
of this work, Steitz shared the 2009 Nobel Prize in Chemistry with various scientists who made immense duties
to the appreciation of ribosome structure.
Move RNA is the third essential sort of RNA and one of the tiniest, normally only 70–90 nucleotides long. It
passes on the correct amino destructive to the site of protein amalgamation in the ribosome. It is the base
coordinating between the tRNA and mRNA that considers the correct amino destructive to be implanted in the
polypeptide chain being fused (as shown in below diagram). Any adjustments in the tRNA or rRNA can achieve
overall issues for the telephone considering the way that both are significant for suitable protein association
A tRNA molecule is a single-stranded molecule that exhibits significant intracellular base pairing, giving it its
characteristic three-dimensional shape. As shown below.
RNA as HereditaryInformation:
Despite the way that RNA doesn't fill in as the inborn information in numerous cells, RNA holds this limit with
regards to certain diseases that don't contain DNA. Appropriately, RNA clearly has the additional capacity to
fill in as innate information. Despite the way that RNA is consistently single relinquished inside cells, there is
colossal grouped assortment in diseases. Rhinoviruses, which cause the typical cold; influenza contaminations;
and the Ebola disease are single-deserted RNA contaminations. Rotaviruses, which cause extraordinary

9. gastroenteritis in adolescents and other immunocompromised individuals, are occasions of twofold surrendered
RNA contaminations. Since twofold surrendered RNA is exceptional in eukaryotic cells, its quality fills in as a
marker of viral malady. The recommendations for a disease having a RNA genome as opposed to a DNA
genome are inspected in more detail in Viruses.
Types of RNA and their Functions
There are many types of RNA, but few are discussed below
Types of RNA:
I. Ribosomal RNA
II. Transfer RNA
III. Small nuclear RNA
IV. Guide RNA
V. Small Regulatory RNA
VI. Antisense RNA
VII. Housekeeping RNA
Function of Ribosomal RNA:
 The fundamental limit of rRNA is in protein amalgamation – in authority to separation RNA and move
RNA to ensure that the codon course of action of the mRNA is made an understanding of accurately into
amino destructive gathering in proteins. To achieve this, rRNA has an indisputable three-dimensional
shape including internal circles and helices that makes express goals inside the ribosome – the A, P and
E districts. The P site is for limiting a creating polypeptide, the A site remains a moving toward tRNA
blamed for an amino destructive. After peptide bond improvement, the tRNA ties rapidly to the E site
before leaving the ribosome. What's more rRNA furthermore has goals for authority to some ribosomal
proteins and mindful assessment has separated the stores in both the RNA and protein.
As shown in image below:

10.  Ribosomal RNA is also conveyed in every cell of each enduring specie. The progression of the inside
synergist districts is moreover particularly proportioned making rRNA a sublime gadget for the
examination of logical arrangement and phylogenetics. There is a differentiation in the pace of
advancement of developments on a shallow level and within rRNA, and nucleotides drew in with focus
reactant activity, for instance, in the course of action of a peptide bond, appear to have started before the
nearness of life on earth. How much two species differentiate in rRNA groupings can give a better than
average measure of their formative partition.
 Various enemy of disease operators target prokaryotic rRNA and starting late the coupling regions for
against contamination specialists, for instance, streptomycin and anti-toxin prescription on rRNA have
been illustrated. It has moreover been exhibited that enemy of microbial check normally starts from
point changes in these coupling goals. For instance, the obstacle of Euglena and E. coli to streptomycin
originates from change during the 16S rRNA gathering. Tantamount results were found for the
restriction of Streptomyces to Spectinomycin. Anti-microbial prescription resistance appears to begin
from changes during the 30S rRNA.
 In anoThe job of tRNA is to read the message of nucleic acids, or nucleotides, and translate it into
proteins, or amino acids. The process of making a protein from an mRNA template is called translation.
How does tRNA read the mRNA? It reads the mRNA in three-letter nucleotide sequences called codons. Each
individual codon corresponds to an amino acid. There are four nucleotides in mRNA. If you do the math to
figure out how many different codons exist, you arrive at 64, or four cubed (4^3). There is one tRNA molecule
for each codon.
Interestingly, there are only 21 amino acids. This brings up the idea that our genetic code is redundant. That is,
we have 64 codons but only 21 amino acids. How do we resolve this? More than one codon can specify for an
amino acid.
each codon has only one corresponding amino acid. Thus, we say that the genetic code is redundant, but not
ambiguous. For example, the codons GUU, GUC, GUA, and GUG all code for Valine (redundancy), and none
of them specify any other amino acid (no ambiguity).

11. So, we now know that the job of tRNA is to bring an amino acid to the ribosome. We also know that each
codon has its own tRNA and that each tRNA has its own amino acid attached to it. Further, we know that the
job of tRNA is to transport amino acids to the ribosome for protein production.
The tRNA doesn't become part of the protein which suggests that tRNA can either be attached to an amino acid
or free. We call this charged or uncharged.
In below image you will see structure and functioning of tRna:
Small nuclear RNA:
Small RNAs play a major role in the post-transcriptional regulation of gene expression. Though RNA was
initially discovered in nematodes and plants,
RNA-mediated regulation is widely found in eukaryotic organisms, and similar small RNA guided regulatory
pathways appear to be operative in prokaryotes.
Eukaryotic small RNAs play critical roles in regulating gene expression in development, cancer biology, anti-
viral defense and chromatin modification.
Researchers have capitalized on regulatory pathways mediated by small RNAs to enable analyses of gene
function not previously possible.
Below you will see the model function of sRNA.

12. Guide RNA:
It involved in processing of RNA or DNA in some organisms.
In kinetoplast Trypanosomes guide RNAs (gRNAs) direct the insertion and or deletion of uridylates in
mitochondrial mRNA. gRNA directed mRNA editing is necessary for the maturation and proper function of
12 out of 18 mitochondrial protein encoding mRNAs
Not surprisingly, proper gRNA function is essential for full completion of the Trypanosome life cycle, as
organisms that have impaired or absent gRNA function do not survive past the procyclic or insect stage of
development
Guide RNA directed editing normally is thought to correct frameshift errors present in the gene sequence
present in the mitochondrial genome as originally described by Benne. Editing of the cytochrome b gene,
however, results not in a frameshift but the generation of a start codon demonstrating that gRNA directed
editing can correct multiple types of genomic sequence errors.
Additionally, several recent studies have demonstrated that guide RNA directed editing might be a
mechanism by which Trypanosomes may regulate the functional diversity of their protein encoding genes.
Recently it was shown that alternate editing of the coxIII gene leads to a novel function of this gene. This
report has led to the speculation that guide RNA directed editing in trypanosomes like alternate splicing in
eukaryotes may be a mechanism to encode for protein diversity and evolutionary adaptation.

13. Antisense RNAs
Antisense RNAs are used to bind to complementary mRNAs and inhibit protein translation. Antisense RNAs
are single stranded RNAs that can be utilized as a laboratory technique to inhibit protein translation. Antisense
RNAs have also been found to be naturally occurring in bacteria such as E. coli with the R1 plasmid. The
antisense RNAs are categorized as small regulatory RNAs due to their small size. They can be divided into
either cis- or trans-antisense RNAs. Cis-antisense RNAs are encoded by an overlap between the antisense RNA
itself and the target gene. In trans-antisense RNAs, the antisense RNA gene is separate from the target gene and
there is no overlap.
this image displays a mechanism of antisense DNA.
However, it is important to note that an antisense RNA functions in the same manner. The antisense RNA can
bind to the mRNA and inhibit translation. In some cases, small regulatory RNAs, not included in the antisense
category, can activate translation as well.
Small Regulatory RNAs
Small regulatory RNAs are non-coding RNA molecules that play a role in cellular processes such as activation
or inhibition processes.
These small regulatory RNAs play a critical role in gene regulation via numerous mechanisms.
The mechanisms by which small regulatory RNAs function include binding to protein targets, protein
modification, binding to mRNA targets, and regulating gene expression.
There are numerous classes of small regulatory RNAs that play a key role in regulation.
House-keeping RNAs
Small regulatory RNAs encompass many RNAs involved in house-keeping processes as well.
House-keeping genes are specific genes that function in maintaining basic cellular processes and a state of
homeostasis.
House-keeping RNAs identified to date include rRNA and tRNAs.
rRNAs that are house-keeping genes can bind to RNA polymerases and regulate transcription or function in
larger complexes that are required for protein secretion or synthesis processes.

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