RNA

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RNA or [[Ribonuceic acid|ribonucleic acid]], is made up of a series of [[Nucleotides|nucleotides]] joined by 3'-5' [[Phosphodiester|phosphodiester]] bonds. RNA forms a polynucleotide strand with a sugar-phosphate backbone. The phosphodiester bonds that make up the backbone have a negative charge, which protects the molecule from being hydrolyzed by a nucleophilic attack as the negative charges of the backbone and [[Nucleophile|nucleophile repel]] each other.  
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RNA or [[Ribonuceic acid|ribonucleic acid]], is made up of a series of [[Nucleotides|nucleotides]] joined by 3'-5' [[Phosphodiester|phosphodiester]] bonds. RNA forms a polynucleotide strand with a sugar-phosphate backbone. The phosphodiester bonds that makes up the backbone has a negative charge, which protects the molecule from being hydrolyzed by a nucleophilic attack as the negative charges of the backbone and [[Nucleophile|nucleophile repel]] each other.  
  
RNA differs from [[DNA|DNA]] it has a [[Ribose|ribose]] sugar, whereas DNA has a deoxyribose sugar, the ribose sugar contains a 2` [[Hydroxyl group|hydroxyl group]]. Like DNA, four nucleotide [[Base|bases]]: [[Cytosine|cytosine]] (C), [[Guanine|guanine]] (G), [[Adenine|adenine ]](A) and [[Uracil|uracil ]](DNA has a [[Thymine|thymine]] base rather than [[Uracil|uracil]]) are attached to the backbone. In RNA, C pairs with G, but A pairs with U instead of T<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]]" secondary structures<ref name="null">Lyons, I, 2011. Biomedical Science Lecture Notes. 1st ed. Oxford: Wiley-Blackwell, p21-23</ref>.  
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RNA differs from [[DNA|DNA]]&nbsp;as it has a [[Ribose|ribose]] sugar, whereas DNA has a deoxyribose sugar. The ribose sugar contains a 2` [[Hydroxyl group|hydroxyl group]]&nbsp;and DNA contains a 3' hydroxyl group. Like DNA, RNA has&nbsp;four nucleotide [[Base|bases]]: [[Cytosine|cytosine]] (C), [[Guanine|guanine]] (G), [[Adenine|adenine ]](A) and [[Uracil|uracil ]](DNA has a [[Thymine|thymine]] base rather than [[Uracil|uracil]]) that are attached to the backbone. In RNA, C pairs with G, but A pairs with U instead of T<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]]" secondary structures<ref name="null">Lyons, I, 2011. Biomedical Science Lecture Notes. 1st ed. Oxford: Wiley-Blackwell, p21-23</ref>, an example of this is in the termination step of transcription.
  
== RNA involved in gene expression ==
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== 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> ===
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=== 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 made in the nucleus during [[Transcription|transcription]]  
 
*Single polynucleotide strand made in the nucleus during [[Transcription|transcription]]  
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*In bacterial organisms like ''E. coli'' the mRNA is polycistronic, whereas in most [[Eukaryote|eukaryotic]] organisms the mRNA only codes for one [[Gene|gene]] (monocistronic).<ref>https://en.wikipedia.org/wiki/Messenger_RNA</ref>
 
*In bacterial organisms like ''E. coli'' the mRNA is polycistronic, whereas in most [[Eukaryote|eukaryotic]] organisms the mRNA only codes for one [[Gene|gene]] (monocistronic).<ref>https://en.wikipedia.org/wiki/Messenger_RNA</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> ===
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=== 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 which is folded into three hairpin-loops which gives it a cloverleaf structure, held together by [[Hydrogen bonds|hydrogen bonds]]  
 
*Single polynucleotide strand which is folded into three hairpin-loops which gives it a cloverleaf structure, held together by [[Hydrogen bonds|hydrogen bonds]]  
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*It is typically 76 to 90 nucleotides in length
 
*It is typically 76 to 90 nucleotides in length
  
=== 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> ===
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=== 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 RNA which forms [[Ribosomes|ribosomes]]  
 
*This is the RNA which forms [[Ribosomes|ribosomes]]  
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The three RNAs all work together to convert the initial DNA molecule into a protein. All three of these types of RNA are synthesized by RNA Polymerase.  
 
The three RNAs all work together to convert the initial DNA molecule into a protein. All three of these types of RNA are synthesized by RNA Polymerase.  
  
=== 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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=== 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  
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*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> ===
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=== 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> ===
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=== 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  
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*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> ===
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=== 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  
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*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> ===
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=== 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  
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RNA can also exist in non-coding forms. These non-coding RNAs function in diverse cell processes, such as telomere synthesis, transport of proteins into the endoplasmic reticulum 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>. Besides, non-coding RNAs also have many applications but many revolve around regulation of [[Gene|gene]] expression, such as [[Riboswitches|riboswitches]] in 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 into the endoplasmic reticulum 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>. Besides, non-coding RNAs also have many applications but many revolve around regulation of [[Gene|gene]] expression, such as [[Riboswitches|riboswitches]] in 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>.  
  
== References ==
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== References ==
  
 
<references />
 
<references />

Latest revision as of 12:17, 5 December 2017

RNA or ribonucleic acid, is made up of a series of nucleotides joined by 3'-5' phosphodiester bonds. RNA forms a polynucleotide strand with a sugar-phosphate backbone. The phosphodiester bonds that makes up the backbone has a negative charge, which protects the molecule from being hydrolyzed by a nucleophilic attack as the negative charges of the backbone and nucleophile repel each other.

RNA differs from DNA as it has a ribose sugar, whereas DNA has a deoxyribose sugar. The ribose sugar contains a 2` hydroxyl group and DNA contains a 3' hydroxyl group. Like DNA, RNA has four nucleotide bases: cytosine (C), guanine (G), adenine (A) and uracil (DNA has a thymine base rather than uracil) that are attached to the backbone. In RNA, C pairs with G, but A pairs with 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], an example of this is in the termination step of transcription.

Contents

RNA involved in gene expression

1. mRNA – messenger RNA[3]

2. tRNA – transfer RNA[5]

3. rRNA – ribosomal RNA[6]

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

4. snRNA - small nuclear RNA[7]

5. snoRNA - small nucleolar RNA[8]

6. scaRNA - small cajal RNA[9]

7. miRNA - microRNA[10]

8. siRNA - small interfering RNA[11]

RNA can also exist in non-coding forms. These non-coding RNAs function in diverse cell processes, such as telomere synthesis, transport of proteins into the endoplasmic reticulum and X-chromosome inactivation[12]. Besides, 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 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. https://en.wikipedia.org/wiki/Messenger_RNA
  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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