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               - DNA is transcribed into mRNA, therefore the mRNA and the DNA are complementary  
               - DNA is transcribed into mRNA, therefore the mRNA and the DNA are complementary  


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; -&nbsp;mRNA carries the [[Genetic code|genetic code]] from the DNA in the nucleus to the [[Ribosomes|ribosomes]] in the [[cytoplasm|cytoplasm]]<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - This mRNA&nbsp;is then used as a template for [[Translation|translation]] into a functional protein<br>&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - mRNA&nbsp;is also used to make copy DNA&nbsp;([[CDNA|cDNA]])  
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; -&nbsp;mRNA carries the [[Genetic code|genetic code]] from the DNA in the nucleus to the [[Ribosomes|ribosomes]] in the [[Cytoplasm|cytoplasm]]<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - This mRNA&nbsp;is then used as a template for [[Translation|translation]] into a functional protein<br>&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - mRNA&nbsp;is also used to make copy DNA&nbsp;([[CDNA|cDNA]])  


<br>2. [[TRNA|tRNA]] – transfer RNA&nbsp;<ref>Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120</ref>  
<br>2. [[TRNA|tRNA]] – transfer RNA&nbsp;<ref>Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120</ref>  


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - Single polynucleotide strand which&nbsp;is folded into a clover shape, held together by [[Hydrogen bonds|hydrogen bonds]]<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - Consists of a specific&nbsp;sequence of three unpaired&nbsp;bases bound&nbsp;to a complementary [[codon|codon]]&nbsp;([[Anticodon|anticodon]])&nbsp;and an&nbsp;[[Amino_acid|amino acid]] binding&nbsp;site  
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - Single polynucleotide strand which&nbsp;is folded into a clover shape, held together by [[Hydrogen bonds|hydrogen bonds]]<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - Consists of a specific&nbsp;sequence of three unpaired&nbsp;bases bound&nbsp;to a complementary [[Codon|codon]]&nbsp;([[Anticodon|anticodon]])&nbsp;and an&nbsp;[[Amino acid|amino acid]] binding&nbsp;site  


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - Found in the [[cytoplasm|cytoplasm]], where it is involved in translation  
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - Found in the [[Cytoplasm|cytoplasm]], where it is involved in translation  


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - This [[Molecule|molecule]]&nbsp;carries&nbsp;amino acids to&nbsp;the ribosomes where a [[Polypeptide|polypeptide]] is formed, the sequence of which was determined by the [[MRNA|mRNA]].  
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - This [[Molecule|molecule]]&nbsp;carries&nbsp;amino acids to&nbsp;the ribosomes where a [[Polypeptide|polypeptide]] is formed, the sequence of which was determined by the [[MRNA|mRNA]].  
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<br>3. [[RRNA|rRNA]] – ribosomal RNA&nbsp;<ref>Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120</ref><br>&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - This is the RNA&nbsp;which forms&nbsp;[[Ribosomes|ribosomes]]<br>&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - It acts as a catalyst for [[Proteins|protein]] synthesis  
<br>3. [[RRNA|rRNA]] – ribosomal RNA&nbsp;<ref>Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120</ref><br>&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - This is the RNA&nbsp;which forms&nbsp;[[Ribosomes|ribosomes]]<br>&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - It acts as a catalyst for [[Proteins|protein]] synthesis  


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - It is synthesised in the [[Nucleolus|nucleolus]]
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; - It is synthesised in the [[Nucleolus|nucleolus]]  


&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- rRNA molecules do not code for protein  
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- rRNA molecules do not code for protein  
The three RNAs all work together to convert the initial DNA molecule into a protein. All three of these types of RNA are synthesised by RNA Polymerase.
<br>
4. snRNA -- small nuclear RNA
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;- commonly known as U-RNA
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;- function in various nuclear processes
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;- function in the splicing of pre-mRNA
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;-&nbsp;transcribed by either RNA polymerase II or RNA polymerase III
<br>
5. snoRNA -- small nucleolar RNA
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;- used to process and modify rRNA chemically
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
6. scaRNA -- small cajal RNA
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; -&nbsp;a class of snoRNAs
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - locate at the Cajal body
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - to modify snoRNA and snRNA
<br>
7. miRNA -- microRNA
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;- non-coding RNA molecule
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;- containing approximately 22 nucleotides
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;- regulate gene expression by blocking translation of selective mRNA
<br>
8. siRNA -- small interfering RNA
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - also known as silencing RNA
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - double stranded RNA molecules
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - turn off gene expression by directing degradation of selective mRNA and the establishment of compact chromatin structures
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;


&nbsp;  
&nbsp;  


The three RNAs all work together to convert the initial DNA molecule into a [[protein|protein]]. All three of these types of RNA are synthesised by [[RNA Polymerase|RNA Polymerase]].
<br>


RNA can also exist in non coding forms. These non-coding RNAs have many applications but many revolve around regulation of [[gene|gene]] expression, such as [[Riboswitches|riboswitches]]&nbsp;in bacteria and miRNAs involved in [[RNAi]]&nbsp;(RNA interference) in animals&nbsp;<ref>Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P,2008, Molecular Biology of the Cell,5th Edition, New York, Garland Science, pg 493</ref>.  
RNA can also exist in non coding forms. These non-coding RNAs function in diverse cell processes, such as telomere synthesis, transport of proteins intot the endoplasmic recticulum and X-chromosome inactivation. Beasides, non-coding RNAs also have many applications but many revolve around regulation of [[Gene|gene]] expression, such as [[Riboswitches|riboswitches]]&nbsp;in bacteria and miRNAs involved in [[RNAi]]&nbsp;(RNA interference) in animals&nbsp;<ref>Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P,2008, Molecular Biology of the Cell,5th Edition, New York, Garland Science, pg 493</ref>.


== References  ==
== References  ==


<references />
<references />

Revision as of 18:32, 27 November 2014

RNA stands for ribonucleic acid. It is made up of a series of nucleotides joined by 3'-5' phosphodiester bonds. RNA forms a polynucleotide strand with a sugar-phosphate backbone. Unlike DNA, RNA has a ribose sugar, which means that it has a 2` hydroxyl group.

Attached to the backbone are 4 bases, in a similar way to DNA, in which cytosine (C) pairs with guanine (G) and thymine (T) pairs with adenine (A). However in RNA C pairs with G, but A pairs with uracil (U) instead of T [1]. RNA is typically single-stranded, although regions can form where the RNA loops back on itself, to produce "hairpin" secondary structures.[2]

RNA involved in gene expression

1. mRNA – messenger RNA [3]
               - Single polynucleotide strand made in the nucleus during transcription              

               - DNA is transcribed into mRNA, therefore the mRNA and the DNA are complementary

               - mRNA carries the genetic code from the DNA in the nucleus to the ribosomes in the cytoplasm
               - This mRNA is then used as a template for translation into a functional protein
               - mRNA is also used to make copy DNA (cDNA)


2. tRNA – transfer RNA [4]

             - Single polynucleotide strand which is folded into a clover shape, held together by hydrogen bonds
             - Consists of a specific sequence of three unpaired bases bound to a complementary codon (anticodon) and an amino acid binding site

             - Found in the cytoplasm, where it is involved in translation

             - This molecule carries amino acids to the ribosomes where a polypeptide is formed, the sequence of which was determined by the mRNA.


3. rRNA – ribosomal RNA [5]
             - This is the RNA which forms ribosomes
             - It acts as a catalyst for protein synthesis

             - It is synthesised in the nucleolus

             - rRNA molecules do not code for protein

The three RNAs all work together to convert the initial DNA molecule into a protein. All three of these types of RNA are synthesised by RNA Polymerase.


4. snRNA -- small nuclear RNA

                 - commonly known as U-RNA

                 - function in various nuclear processes

                 - function in the splicing of pre-mRNA

                 - transcribed by either RNA polymerase II or RNA polymerase III


5. snoRNA -- small nucleolar RNA

                   - used to process and modify rRNA chemically

                   

6. scaRNA -- small cajal RNA

                  - a class of snoRNAs

                  - locate at the Cajal body

                  - to modify snoRNA and snRNA


7. miRNA -- microRNA

                 - non-coding RNA molecule

                 - containing approximately 22 nucleotides

                 - regulate gene expression by blocking translation of selective mRNA


8. siRNA -- small interfering RNA

                - also known as silencing RNA

                - double stranded RNA molecules

                - turn off gene expression by directing degradation of selective mRNA and the establishment of compact chromatin structures

                 

 


RNA can also exist in non coding forms. These non-coding RNAs function in diverse cell processes, such as telomere synthesis, transport of proteins intot the endoplasmic recticulum and X-chromosome inactivation. Beasides, non-coding RNAs also have many applications but many revolve around regulation of gene expression, such as riboswitches in bacteria and miRNAs involved in RNAi (RNA interference) in animals [6].

References

  1. ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 109
  2. ↑ Lyons, I, 2011. Biomedical Science Lecture Notes. 1st ed. Oxford: Wiley-Blackwell, p21-23
  3. ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 119
  4. ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120
  5. ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120
  6. ↑ Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P,2008, Molecular Biology of the Cell,5th Edition, New York, Garland Science, pg 493
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