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RNA stands for ribonucleic acid. It is made up of a series of [[Nucleotides|nucleotides]] joined by 3'-5'&nbsp;[[Phosphodiester|phosphodiester]] bonds. RNA&nbsp;forms a polynucleotide strand with a sugar-phosphate backbone. Unlike [[DNA]], RNA has a [[Ribose|ribose]] sugar, which means that it has a 2` [[Hydroxyl group|hydroxyl group]]. The phosphodiester bonds that make up the backbone have a negative charge, this ensures it cannot be hydrolysed by nucleophilic attack, for example by hydroxide ions, as the negative charges repel each other.<ref>Berg, J.M., Tymoczko, J.L., and Stryer, L. (2011). Biochemistry. 7th ed. New York: W. H. Freeman and Company. 115.</ref>
RNA stands for ribonucleic acid. It is made up of a series of [[Nucleotides|nucleotides]] joined by 3'-5'&nbsp;[[Phosphodiester|phosphodiester]] bonds. RNA&nbsp;forms a polynucleotide strand with a sugar-phosphate backbone. Unlike [[DNA]], RNA has a [[Ribose|ribose]] sugar, which means that it has a 2` [[Hydroxyl group|hydroxyl group]]. The phosphodiester bonds that make up the backbone have a negative charge, this ensures it cannot be hydrolysed by nucleophilic attack, for example by hydroxide ions, as the negative charges repel each other.<ref>Berg, J.M., Tymoczko, J.L., and Stryer, L. (2011). Biochemistry. 7th ed. New York: W. H. Freeman and Company. 115.</ref>  


Attached to the backbone are 4 [[Base|bases]], in a similar way to DNA, in which&nbsp;[[Cytosine|cytosine]] (C) pairs with [[Guanine|guanine]] (G) and [[Thymine|thymine]] (T) pairs with [[Adenine|adenine]] (A). However in RNA&nbsp;C pairs with G, but A pairs with [[Uracil|uracil]] (U) instead of T&nbsp;<ref>Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 109</ref>. RNA is typically single-stranded, although regions can form where the RNA loops back on itself, to produce "[[Hairpin|hairpin]]"&nbsp;secondary structures.<ref name="null">Lyons, I, 2011. Biomedical Science Lecture Notes. 1st ed. Oxford: Wiley-Blackwell, p21-23</ref>  
Attached to the backbone are 4 [[Base|bases]], in a similar way to DNA, in which&nbsp;[[Cytosine|cytosine]] (C) pairs with [[Guanine|guanine]] (G) and [[Thymine|thymine]] (T) pairs with [[Adenine|adenine]] (A). However in RNA&nbsp;C pairs with G, but A pairs with [[Uracil|uracil]] (U) instead of T&nbsp;<ref>Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 109</ref>. RNA is typically single-stranded, although regions can form where the RNA loops back on itself, to produce "[[Hairpin|hairpin]]"&nbsp;secondary structures.<ref name="null">Lyons, I, 2011. Biomedical Science Lecture Notes. 1st ed. Oxford: Wiley-Blackwell, p21-23</ref>  
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&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<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- rRNA molecules do not code for protein<br>  


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>
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<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. Page 336</ref>  
4. snRNA -- small nuclear RNA<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. Page 336</ref>  
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&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;-&nbsp;transcribed by either RNA polymerase II or RNA polymerase III  
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;-&nbsp;transcribed by either RNA polymerase II or RNA polymerase III  


<br>
<br>  


5. snoRNA -- small nucleolar RNA<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. Page 336</ref>  
5. snoRNA -- small nucleolar RNA<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. Page 336</ref>  
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&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - to modify snoRNA and snRNA  
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - to modify snoRNA and snRNA  


<br>
<br>  


7. miRNA -- microRNA<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. Page 336</ref>  
7. miRNA -- microRNA<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. Page 336</ref>  
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&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;- regulate gene expression by blocking translation of selective mRNA  
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;- regulate gene expression by blocking translation of selective mRNA  


<br>
<br>  


8. siRNA -- small interfering RNA<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. Page 336</ref>  
8. siRNA -- small interfering RNA<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. Page 336</ref>  
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&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; - double stranded RNA molecules  
&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<br>
&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<br>  


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<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. Page 336</ref>. 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>.  
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<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. Page 336</ref>. 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>.  

Revision as of 15:11, 1 December 2015

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. The phosphodiester bonds that make up the backbone have a negative charge, this ensures it cannot be hydrolysed by nucleophilic attack, for example by hydroxide ions, as the negative charges repel each other.[1]

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 [2]. RNA is typically single-stranded, although regions can form where the RNA loops back on itself, to produce "hairpin" secondary structures.[3]

RNA involved in gene expression

1. mRNA – messenger RNA [4]
               - 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 [5]

             - 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 [6]
             - 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[7]

                 - 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[8]

                   - used to process and modify rRNA chemically

                   

6. scaRNA -- small cajal RNA[9]

                  - a class of snoRNAs

                  - locate at the Cajal body

                  - to modify snoRNA and snRNA


7. miRNA -- microRNA[10]

                 - non-coding RNA molecule

                 - containing approximately 22 nucleotides

                 - regulate gene expression by blocking translation of selective mRNA


8. siRNA -- small interfering RNA[11]

                - 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[12]. 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 [13].

References

  1. ↑ Berg, J.M., Tymoczko, J.L., and Stryer, L. (2011). Biochemistry. 7th ed. New York: W. H. Freeman and Company. 115.
  2. ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 109
  3. ↑ Lyons, I, 2011. Biomedical Science Lecture Notes. 1st ed. Oxford: Wiley-Blackwell, p21-23
  4. ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 119
  5. ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120
  6. ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120
  7. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M.,Roberts, K., Walter, P. (2008). Molecular Biology of The Cell 5th edition. New York: Garland Science. Page 336
  8. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M.,Roberts, K., Walter, P. (2008). Molecular Biology of The Cell 5th edition. New York: Garland Science. Page 336
  9. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M.,Roberts, K., Walter, P. (2008). Molecular Biology of The Cell 5th edition. New York: Garland Science. Page 336
  10. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M.,Roberts, K., Walter, P. (2008). Molecular Biology of The Cell 5th edition. New York: Garland Science. Page 336
  11. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M.,Roberts, K., Walter, P. (2008). Molecular Biology of The Cell 5th edition. New York: Garland Science. Page 336
  12. ↑ Alberts, B., Johnson, A., Lewis, J., Raff, M.,Roberts, K., Walter, P. (2008). Molecular Biology of The Cell 5th edition. New York: Garland Science. Page 336
  13. ↑ 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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