Molecular Biology

1. STRUCTURE &
FUNCTION OF RNA
INDRANI KAR
M.Sc Microbiology
St. George College of Management & Science
Bengaluru North University

2. I N T R O D U C T I O N
• RNA usually exist as a single stranded polypeptide, consists of
complementary nucleotides.
• RNA are mainly three major types- transfer RNA, messenger RNA, ribosomal
RNA.
• All the three molecules resembles the DNA strands regions, intramolecular
and interspersed, have some double stranded regions.
• RNA molecules are hydrolyzed by chemically or enzymatically, at pH1 RNA
molecules hydrolyzed and releasing into phosphodiesters bond , sugars and
broken base pairs.

3. STRUCTURE OF RNA
• RNA process and especially in the translation of the genetic codon involves as more
versatile in almost all crucial life.
• The four ribonucleosides that incorporate the purine bases adenine (A), guanine (
G) and the pyrimidine bases uracil (U), cytosine ( C) constitutes the basic building
blocks of a RNA.
• These residues compromises a ribose sugar ring and a purine ( A, G ) or pyrimidine
(C, U ) base.
• They are connected together by the phosphodiesters linkage, its phosphodiesters
unit is called a nucleotide and form complementary strands.

5. Continue.....
• The two complementary strands results in the formation of a right handed double
helical structures, the biological RNA molecules need more specificity in order to
active more biological functions.
• Non Watson crick base association are often found in RNA structure where they serves
as specific regions also called recognize elements, and ligands and have ion - binding
sites.
• Wobble base pairs are typically found in the RNA molecules and can be inserted
without great distortion into regular Watson crick helix.

7. Primary, secondary and tertiary structures
of RNA

8. Continue....
• The most straight forward definition of secondary structure would include any nucleotides such as atleast itself
and one at least of its immediate neighours in the 5' or 3' directions are involved in classical base pairs.
• The secondary structure will define various elements, a hairpin loop is formed when an RNA strand folds back
on itself.
• In the internal loop for which only one nucleotides is unpaired on each strand.
• A bulge has unpaired nucleotides on only one strand , in the other strand has uninterrupted base pairs.
• A multi branched loop occurs when double stranded regions separated by any number of unpleasant
nucleotides come together.

9. Brief description of the different
types of RNA and there functions

10. Types of the RNA
Depends on the structure RNA are divided into sometimes-
a. Small nuclear RNAs
b. Micro RNAs
c. Small interfering RNAs
d. RNA interference
e. Small nucleolar RNAs

11. Small nuclear RNAs
• Small nuclear RNAs are small RNA molecules that are found in the nucleus of the eukaryotic.
• There are usually 300 nucleotides or smaller and the nucleus contains more than just snRNA.
• The function of small nuclear RNAs was discovered before the ribosome enzymes.
• The function of the small nuclear RNAs are important in the processing of the pre RNA splicing and
processing, which removes the introns, involves in the maintenance of the telomerase or end of
the chromosome.
• They are also serves as the catalyst and change the views of the molecular invention.

12. Small nuclear RNAs

13. Micro RNAs
• Micro RNAs is the gene regulatory small RNA that is typically 21-23 nucleotides
long.
• It is the similar to small interfering RNAs in that they hind to complementary mRNA
molecules and inhibit their translation.
• Micro RNAs are a single stranded RNA and only partially complement with the
mRNA .
• It is used for the growth development and insulin secretion among other things.
• It is found to be too much micro RNA to implicate disease such as mental
retardation.

15. Small interfering RNAs
• It is also known as interference RNA, silencing RNA, discovered by the researchers in the
laboratory.
• There are roughly 20-25 nucleotides in length and are double stranded RNA molecules
overhangging 2 nucleotides on the 3' ends.
• They are responsible for the expression of the gene such as antiviral mechanisms and shaping the
chromatic structure.
• This allows in the drug development of biomedical fields such as cure of human
immunodeficiency virus.

16. Interfering RNAs

17. RNA interference
• RNA interference was discovered by the by Mello and Andrew in the 1990s, antisense RNA
experiment.
• It is the process in which double stranded RNA triggers the degradation of the homologous
mRNA .
• It is used to degrade mRNA in the cell to shut down the effects of the specific genes, which
gets gene expression.
• The RNA interference can either be injected into specific cells or modified viruses to transfect
the cells.

18. RNA interference

19. Small nucleolar RNAs
• Those are modified ribosomal RNAs by mediating the
cleavage of long pre - massenger RNA in the
complementary mRNA molecules as the functional
subunit and it can also add last functional subunit.

20. Small nucleolar RNAs

21. CONCLUSION
• Non coding RNA is basically any RNA molecules is not translated into the proteins, it's
significant as growing small cells, regulations of the gene.
• There are different types of RNA that are similar in structure bt function differently such as
transfer RNA, massenger RNA, ribosomal RNA.
• Antisense RNA is an RNA strand that is complementary mRNA, transcribed within the cell.
• The RNA is a single stranded RNA molecules, is brought into the cell inorder to inhibit
translation.

22. THANK YOU