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== RNA involved in gene expression  ==
== RNA involved in gene expression  ==


1. [[MRNA|mRNA]] – messenger RNA <ref>Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 119</ref>  
=== 1. [[MRNA|mRNA]] – messenger RNA <ref>Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 119</ref> ===


**Single polynucleotide strand madein the nucleus during [[Transcription|transcription]]  
*Single polynucleotide strand madein the nucleus during [[Transcription|transcription]]  
**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  
**mRNA carries the [[Genetic code|genetic code]] from the DNA in the nucleus to the [[Ribosomes|ribosomes]] in the [[Cytoplasm|cytoplasm]]<br>** This mRNAis then used as a template for [[Translation|translation]] into a functional protein<br>** mRNAis also used to make copy DNA([[CDNA|cDNA]])
*mRNA carries the [[Genetic code|genetic code]] from the DNA in the nucleus to the [[Ribosomes|ribosomes]] in the [[Cytoplasm|cytoplasm]]<br>* This mRNAis then used as a template for [[Translation|translation]] into a functional protein  
*mRNAis also used to make copy DNA([[CDNA|cDNA]])


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


**Single polynucleotide strand whichis folded into a clover shape, held together by [[Hydrogen bonds|hydrogen bonds]]<br>** Consists of a specificsequence of three unpairedbases boundto a complementary [[Codon|codon]]([[Anticodon|anticodon]])and an[[Amino acid|amino acid]] bindingsite  
*Single polynucleotide strand whichis folded into a clover shape, held together by [[Hydrogen bonds|hydrogen bonds]]<br>* Consists of a specificsequence of three unpairedbases boundto a complementary [[Codon|codon]]([[Anticodon|anticodon]])and an[[Amino acid|amino acid]] bindingsite  
**Found in the [[Cytoplasm|cytoplasm]], where it is involved in translation  
*Found in the [[Cytoplasm|cytoplasm]], where it is involved in translation  
**This [[Molecule|moleculecarriesamino]] acids tothe ribosomes where a [[Polypeptide|polypeptide]] is formed, the sequence of which was determined by the [[MRNA|mRNA]].
*This [[Molecule|moleculecarriesamino]] acids tothe ribosomes where a [[Polypeptide|polypeptide]] is formed, the sequence of which was determined by the [[MRNA|mRNA]].


3. [[RRNA|rRNA]] – ribosomal RNA<ref>Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120</ref>  
=== 3. [[RRNA|rRNA]] – ribosomal RNA<ref>Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120</ref> ===


**This is the RNAwhich forms[[Ribosomes|ribosomes]]  
*This is the RNAwhich forms[[Ribosomes|ribosomes]]  
**It acts as a catalyst for [[Proteins|protein]] synthesis  
*It acts as a catalyst for [[Proteins|protein]] synthesis  
**It is synthesised in the [[Nucleolus|nucleolus]]
*It is synthesised in the [[Nucleolus|nucleolus]]  
 
*rRNA molecules do not code for protein
- 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> ===


**commonly known as U-RNA  
*commonly known as U-RNA  
**function in various nuclear processes  
*function in various nuclear processes  
**function in the splicing of pre-mRNA  
*function in the splicing of pre-mRNA  
**transcribed by either RNA polymerase II or RNA polymerase III
*transcribed by either RNA polymerase II or RNA polymerase III


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> ===


**used to process and modify rRNA chemically
*used to process and modify rRNA chemically


6. scaRNA - small cajal 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>  
=== 6. scaRNA - small cajal 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> ===


**a class of snoRNAs  
*a class of snoRNAs  
**locate at the Cajal body  
*locate at the Cajal body  
**to modify snoRNA and snRNA
*to modify snoRNA and snRNA


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> ===


**non-coding RNA molecule  
*non-coding RNA molecule  
**containing approximately 22 nucleotides  
*containing approximately 22 nucleotides  
**regulate gene expression by blocking translation of selective mRNA
*regulate gene expression by blocking translation of selective mRNA


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> ===


**also known as silencing RNA  
*also known as silencing RNA  
**double stranded RNA molecules  
*double stranded RNA molecules  
**turn off gene expression by directing degradation of selective mRNA and the establishment of compact chromatin structures<br>
*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|riboswitchesin]] bacteria and miRNAs involved in [[RNAi]](RNA interference) in animals<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|riboswitchesin]] bacteria and miRNAs involved in [[RNAi]](RNA interference) in animals<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 15:32, 1 December 2015

RNA stands for ribonucleic acid. It is made up of a series of nucleotides joined by 3'-5'phosphodiester bonds. RNAforms 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 whichcytosine (C) pairs with guanine (G) and thymine (T) pairs with adenine (A). However in RNAC 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 madein 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 mRNAis then used as a template for translation into a functional protein
  • mRNAis also used to make copy DNA(cDNA)

2. tRNA – transfer RNA[5]

3. rRNA – ribosomal RNA[6]

  • This is the RNAwhich formsribosomes
  • 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 riboswitchesin 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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