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Rna interference technology

In Structure and Function of RNA , we described the function of mRNA, rRNA, and tRNA. In addition to these types of RNA, cells also produce several types of small noncoding RNA molecules that are involved in the regulation of gene expression. These include antisense RNA molecules, which are complementary to regions of specific mRNA molecules found in both prokaryotes and eukaryotic cells. Non-coding RNA molecules play a major role in RNA interference (RNAi) , a natural regulatory mechanism by which mRNA molecules are prevented from guiding the synthesis of proteins. RNA interference of specific genes results from the base pairing of short, single-stranded antisense RNA molecules to regions within complementary mRNA molecules, preventing protein synthesis. Cells use RNA interference to protect themselves from viral invasion, which may introduce double-stranded RNA molecules as part of the viral replication process ( [link] ).

A eukaryotic cell transcribes a region of DNA into mrNA. Antisense mRNA then binds to the this mRNA to produce a double stranded region. This region is not translated (which means that ribosomes do not bind to the mRNA to produce proteins).
Cells like the eukaryotic cell shown in this diagram commonly make small antisense RNA molecules with sequences complementary to specific mRNA molecules. When an antisense RNA molecule is bound to an mRNA molecule, the mRNA can no longer be used to direct protein synthesis. (credit: modification of work by Robinson R)

Researchers are currently developing techniques to mimic the natural process of RNA interference as a way to treat viral infections in eukaryotic cells. RNA interference technology involves using small interfering RNAs (siRNAs) or microRNAs (miRNAs) ( [link] ). siRNAs are completely complementary to the mRNA transcript of a specific gene of interest while miRNAs are mostly complementary. These double-stranded RNAs are bound to DICER, an endonuclease that cleaves the RNA into short molecules (approximately 20 nucleotides long). The RNAs are then bound to RNA-induced silencing complex (RISC), a ribonucleoprotein. The siRNA-RISC complex binds to mRNA and cleaves it. For miRNA, only one of the two strands binds to RISC. The miRNA-RISC complex then binds to mRNA, inhibiting translation. If the miRNA is completely complementary to the target gene, then the mRNA can be cleaved. Taken together, these mechanisms are known as gene silencing .

Double stranded RNA can be produced from DNA in the nucleus. Dicer than cuts this dsRNA into either miRNA or siRNA. miRNA is an imperfect match and only one strand is usually incorporated into RISC. This blocks translation but the mRNA is stable. The RISC is stuck on the target. The siRNA has a perfect match and is incorporated into RISC. This triggers mRNA cleavage.
This diagram illustrates the process of using siRNA or miRNA in a eukaryotic cell to silence genes involved in the pathogenesis of various diseases. (credit: modification of work by National Center for Biotechnology Information)

Key concepts and summary

  • The science of genomics allows researchers to study organisms on a holistic level and has many applications of medical relevance.
  • Transcriptomics and proteomics allow researchers to compare gene expression patterns between different cells and shows great promise in better understanding global responses to various conditions.
  • The various –omics technologies complement each other and together provide a more complete picture of an organism’s or microbial community’s ( metagenomics ) state.
  • The analysis required for large data sets produced through genomics, transcriptomics, and proteomics has led to the emergence of bioinformatics .
  • Reporter genes encoding easily observable characteristics are commonly used to track gene expression patterns of genes of unknown function.
  • The use of recombinant DNA technology has revolutionized the pharmaceutical industry, allowing for the rapid production of high-quality recombinant DNA pharmaceuticals used to treat a wide variety of human conditions.
  • RNA interference technology has great promise as a method of treating viral infections by silencing the expression of specific genes

Fill in the blank

The application of genomics to evaluate the effectiveness and safety of drugs on the basis of information from an individual’s genomic sequence is called ____________.

pharmacogenomics or toxicogenomics

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A gene whose expression can be easily visualized and monitored is called a ________.

reporter gene

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True/false

RNA interference does not influence the sequence of genomic DNA.

true

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Short answer

If all cellular proteins are encoded by the cell’s genes, what information does proteomics provide that genomics cannot?

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Questions & Answers

reactions if viruses to physical and chemical agents?
VICTOR Reply
All viruses contain the following two components: 1) a nucleic acid genome and 2) a protein capsid that covers the genome. Together this is called the nucleocapsid. In addition, many animal viruses contain a 3) lipid envelope. The entire intact virus is called the virion.
Asali
assume you have performed a gram stain on a sample of pus from a patients urethra. you see red, nucleated cells and purple rods. what can you conclude
Petty Reply
bacteria
ABUBAKAR
Study of micro organisation which we cannot see with naked eye...
shyam Reply
Despite their bad reputation, microbes are mostly beneficial or have a neutral effect on our lives. Microbiology is the scientific study of these microorganisms. Microorganisms are those organisms that are too small to see with the naked eye and include things like bacteria, fungi, and viruses.
Asali
yes
Dhirender
not 'things'...'organisms' like bacterias, viruses and fungi
Sinmi
simi, it's not bacterias but bacteria which is the plural form of the word while bacterium is the singular of it
Richard
bacterium is obvio in a singular form but plural of bacterium is bacterias
Sinmi
Richard is right it's bacterium which is the singular form and plural is bacteria. *Bacterias* doesn't exist.
Aakriti
what is microbiology?
Sandeep Reply
what is microbiology
Glory
is the study of small microorganisms that can't be viewed by our naked eyes under a microscope
Nabukwasi
it's the study of microbes their classification, diversity, their cellular structure and processes, their applications and interaction with other organisms.
Chaitanya
what is EMP pathway
rajesh
which organism is implicated in meningoencephalitis
Peter Reply
Herpes virus
Carlos
Yeah
Laxmi
which mold is called dairy mold?
Gopinath
mushroomm
Top
Geotrichum candidum
Gopinath
hi
bio
Hlw
Laxmi
which infectious agent is the smallest
Sinmi
spore or virus
Anushree
prion ....it is a single protein in a misfolded form..there is also a theory based on it
Sinmi
yup...m sry
Anushree
yes it can be turned as a virus
Sinmi
which gram positive bacteria is responsible for food poisoning?
Sinmi
prion is not a living organism yet it is infectoois why
Jeevan
prions are virus like organism. and it is a misfolded protein that may cause disease to us.
Tharra
Clostridium perfringens, B.cereus
Sneha
Who is the father of the biology
Dhirender
I have one more question. . that who is the father of botany and medicine? ? can any one tell
Dhirender
define polar bond in simple way
Rashmi Reply
when there is formation of positive and negative poles i.e. one atom is +ve and other is -ve which further results in the dipole moment. Such bond is know as polar bond. It is a convalent bond only.
Aakriti
Hi everyone, is these site only about microbiology? I want a site which I can download articles on hematological and biochemical profile
Peter Reply
I think it is only about micro biology.
Kimberly
so whats happening
Michael
I am about to enter school and am going for MCB
Olugbenga Reply
What is DNA damage and repair
Sree Reply
removal of nucleotide bases from DNA is damage n addition or insertion of bases in DNA is repair.
Rashmi
replication is a term related to generation of new DNA from a parental DNA.
Rashmi
role of microorganism as pathogens
Parteek Reply
to live inside the host body, reproduction n destroy the immune system of host body.
Rashmi
what is replication
rajesh
please give me ans
rajesh
replication is a term related to generation of new DNA from parental DNA.
Rashmi
difference between endotoxin and exotoxin
Binkheir Reply
toxins released inside the cell or a body is endotoxin n toxins released outside the cell or a body is exotoxin.
Rashmi
Generally, exotoxins are produced by gram positive bacteria and endotoxins are the integral part of the cell wall of gram negative bacteria. But some gram negative bacteria can also produced exotoxins such as E.coli.
Aakriti
Yeah u r ryt aakarti exotoxins screted by gram postive bacteria nd secreted by cell surface and they are secondary metabolites ....On the other hand endotoxin released by gram negtive bacteria nd released inside the cell (lipopolysaccharide) ..
Bharat
Heat stable lipopolysaccharides to be exact.
Aakriti
yup..
Bharat
please I want the names of bacteria and the diseases they cause.
Ibrahim Reply
there are many we classify it according to their shapes gram negative or gram positive
Tharra
so u may refer the book u guess or by when u want I can do a list for you and send u here
Tharra
😊
Tharra
please do a list for me
Ibrahim
I have the lost but it's too much to type ..
Tharra
MSc entrance prepare books and questions LA etha base pani irukum..
Guhan Reply
kushal always prescott is the imp book to follow.search some objective mcqs books based on your syllabus
deepthi Reply
I want to clear entrance of ms university so I have no more idea so my preparation is based on my bachlor studies.
Kushal
what are the opportunistic infection in aids stage
Kalkak
certain cancer or pneumonia 🤔
Kushal
penicillium crysogenum
Kushal Reply

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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