The RNA world is still expanding !

The ever expanding world of RNA

RNA or ribonucleic acids differ from DNA or deoxyribonucleic acids in having the sugar ribose in place of deoxyribose as well as having one less oxygen atom at the ribose. Secondly, in RNA the base thymine (T) is replaced with uracil (U). So the genetic alphabet has five letters: A, C, G, T and U.

Ribose Deoxyribose

The RNA World

When I was a kid I remember that when working in the fields of my father’s farm together with my late grandfather we where tossing a bunch of questions around during our regular spreading of manure onto the fields to fertilize them.

One of these questions was “What came first, the chicken or the egg?” This was before I knew of the science of molecular biology and many years later finally earned a Ph. D. in cell biology.

Now the question has evolved to “What came first proteins, DNA or RNA?”

The RNA world hypothesis, first supported by Carl Woese in 1967, speculates that the origin of life got started by simple self replicating RNA molecules that through natural selection may have evolved into life as we know it today. Furthermore, the “RNA world” refers to a hypothetical stage in the origin of life on Earth in which RNA carried out the storage of information and acted as an enzyme as well. This hypothesis assumes that RNA molecules assembled themselves randomly in the primordial soup and carried out simple metabolic activities. The discoveries of self splicing RNA molecules, ribozymes, ribosomes and RNA based molecular switches are now considered as a support for this hypothesis.


Today, using improved synthetic and biochemical methods, DNA polymers, long and small double stranded DNA and RNA molecules,  RNA polymers, small and large peptides and small proteins can now be routinely synthesized.


New generations of  artificial nucleic acid such as bridged nucleic acids (BNAs) are promising tools for the study of the expanding RNA world.


 We at Biosynthesis Inc. can help you with all your synthesis needs.


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The following shows a collections of abbreviations for different types of RNA families

RNAs that are important for protein synthesis

Abbreviation Type Function Found in
mRNA Messenger RNA Codes for proteins All organisms
rRNA Ribosomal RNA Translation All organisms
7SL RNA or SRP RNA Signal recognition particle RNA Membrane integration All organisms
tRNA Transfer RNA Translation All organisms
tmRNA Transfer-messenger RNA Transfer and messenger RNARescues stalled ribosomesMediates degradation of the aberrant mRNA.Adds a degradation tag to the aberrant protein for directed proteolysis All organisms

RNAs involved in post-transcriptional modification or DNA replication

Abbreviation Type Function Found in
snRNA Small nuclear RNA Splicing and other fucntions Eukaryotes and archaea
snoRNA Small nucleolar RNA Nucleotide modification of RNAs Eukaryotes and archaea
SmY SmY RNA mRNA trans-splicing Nematodes
scaRNA Small Cajal body-specific RNA Type of snoRNA; Nucleotide modification of RNAs
gRNA Guide RNA gRNA mRNA nucleotide modification Kinetoplastid mitochondria
RNase P Ribonuclease P tRNA maturation. Ribozyme that cleaves RNA. All organisms
RNase MRP Ribonuclease MRP rRNA maturation and DNA replication Eukaryotes
Y Y RNA RNA processing and DNA replication Animals
telRNA Telomerase RNA Telomere synthesis Most eukaryotes
slRNA Spliced leader RNA SL1 RNA located in the spacer region between 5S-rRNA genes where it is involved in trans-splicing Eukaryotes

Regulatory RNAs

Abbreviation Type Function Found in
aRNA Antisense RNA Transcriptional attenuationmRNA degradationmRNA stabilizationTranslation block All organisms
Chi sgRNA Chimeric single guide RNA Functional portion of crRNA and tracrRNA to form a targeted RNA-guided endonuclease (RGEN)
cnaRNA Cis-natural antisense transcript RNA Gene regulation. Natural antisense transcripts (NATs) Multipe eukaryotes
crRNA CRISPR RNA Resistance to parasites, probably by targeting their DNA Bacteria and archaea
esiRNA Endoribonuclease prepared siRNAs Endoribonuclease prepared siRNAs (esiRNAs) are complex pools of siRNAs, which are produced from a long dsRNA by digestion with an enzyme from the RNaseIII family that mimic ex vivo the digestion by the protein Dicer.
gRNA Guide RNA Guides the insertion or deletion of uridine residues into mitochondrial mRNAs in a process known as RNA editing. kinetoplastid protists
lncRNA Long noncoding RNA Various functions Eukaryotes
miRNA MicroRNA Gene regulation Most eukaryotes
piRNA Piwi-interacting RNA Transposon defense and maybe other functions Most animals
Pro-siRNA His-tagged p19 long hairpin RNA Engineered His-p19 long (.100 nt) hairpin RNA encoding sense and antisense strands specific for target genes allows purification of ~21 nt RNAs called pro-siRNAs
RNAi Interference RNA Gene regulation. Repression of gene expression Most eukaryotes
sgRNA Single guide RNA Mitochondrial mRNA editing Bacteria Trypanosoma brucei
shRNA Short –hairpin RNA Gene silencing Mammals
siRNA Small-interfering RNA; RNAi Gene regulation. Repression of gene expression Most eukaryotes
tasiRNA Trans-acting RNA Gene regulation Land plants
tracrRNA Trans-activating crRNAs Guide the enzyme Cas9 endonuclease to recognize and cleave a site in non self DNAAdaptive i\mmune system. Bacteria and archaea
rasiRNA Repeat associated siRNA Type of piRNA; transposon defense Drosophila
7SK 7SK RNA 7SK negatively regulating CDK9/cyclin T complex

Parasitic RNAs

Type Function Found in
Retrotransposones Self-propagating Eukaryotes and some bacteria
Viral genome Information carrier Double-stranded RNA viruses, positive-sense RNA viruses, negative-sense RNA viruses, many satellite viruses and reverse transcribing viruses 
Viroid Self-propagating Infected plants
Satellite RNA Self-propagating Infected cells

Other RNAs

Abbreviation Type Function Found in
5’-AppRNA 5’-adenylated RNA Plays a central role in  nucleic acid ligation Bacteriophage T4
cfRNA Cell-free RNA cfRNA are found to circulated in human blood in cancer patients Humans
dsRNA Double stranded RNA dsRNA induce RNAi
L ds RNA Long double-stranded RNA
pRNA Bacteriophage pRNA Packaging of the viral genome into a pre-fromed viral procapsid Bacteriophages
S dsRNA Short double-stranded RNA
ssRNA Single stranded RNA
vRNA or vtRNA Vault RNAs Expulsion of xenobiotics; drug resistence Humans




Categories: BNA RNA, DNA, DNA Analysis, DNA Editing, DNA finger printing, Epigenetics, Gene Expression, lncRNA, Long noncoding RNA, miRNA, non-coding RNAs, Oligonucleotide Synthesis, RNA Editing, RNA silencing, RNA World, RNA World Hypothesis, RNAi, Virus

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