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 hydrolysed by 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 make up the backbone have a negative charge, which protects the molecule from being hydrolysed by nucleophilic attack as the negative charges of the backbone and [[Nucleophile|nucleophile repel]] each other.
  
RNA differs from DNA as it has a [[Ribose|ribose]] sugar, whereas DNA has a deoxyribose sugar, the ribose sugar contains a 2` [[Hydroxyl group|hydroxyl group]]. Like DNA,&nbsp;four nucleotide&nbsp;[[Base|bases]]:&nbsp;[[Cytosine|cytosine]] (C),&nbsp;[[Guanine|guanine]] (G),&nbsp;[[Adenine|adenine ]](A) and [[Uracil|uracil ]](DNA has a&nbsp;[[Thymine|thymine]]&nbsp;base rather than [[Uracil|uracil]]) are attached to the backbone. In RNA, C pairs with G, but A pairs with&nbsp;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 as 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>.  
  
 
== RNA involved in gene expression  ==
 
== RNA involved in gene expression  ==
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*Single polynucleotide strand which is folded into three hairpinloops which gives it a clover leaf structure, held together by [[Hydrogen bonds|hydrogen bonds]]  
 
*Single polynucleotide strand which is folded into three hairpinloops which gives it a clover leaf structure, held together by [[Hydrogen bonds|hydrogen bonds]]  
*Consists of a specific sequence of three unpairedbases bound to a complementary [[Codon|codon]]&nbsp;([[Anticodon|anticodon]]) and an&nbsp;[[Amino acid|amino acid]] binding site  
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*Consists of a specific sequence of three unpairedbases bound to a complementary [[Codon|codon]] ([[Anticodon|anticodon]]) and an [[Amino acid|amino acid]] binding site  
 
*Found in the [[Cytoplasm|cytoplasm]], where it is involved in translation  
 
*Found in the [[Cytoplasm|cytoplasm]], where it is involved in translation  
 
*This [[Molecule|molecule]] carries amino acids to the ribosomes where a [[Polypeptide|polypeptide]] is formed, the sequence of which was determined by the [[MRNA|mRNA]].  
 
*This [[Molecule|molecule]] carries amino acids to the ribosomes where a [[Polypeptide|polypeptide]] is formed, the sequence of which was determined by the [[MRNA|mRNA]].  
*It is typically 76 to 90 nucleotides in length&nbsp;
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*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>  ===
 
=== 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&nbsp;[[Ribosomes|ribosomes]]  
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*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  
*tRNA has two subunits: large subunit (LSU) and small subunit (SSU). Large subunit acts as ribozymes which catalyse peptide bond formation. In animals the size of the large subunit is 60s and 20s of the small subunit thus ribosome is 80s overall in&nbsp;Eukaryotes.  
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*tRNA has two subunits: large subunit (LSU) and small subunit (SSU). Large subunit acts as ribozymes which catalyse peptide bond formation. In animals the size of the large subunit is 60s and 20s of the small subunit thus ribosome is 80s overall in Eukaryotes.  
*It is used to work out evoutionary patterns between species since they are all form of lifes.
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*It is used to work out evolutionary patterns between species since they are all form of life.
  
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>
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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 synthesised 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>  ===
 
=== 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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*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  
*double stranded RNA molecules  
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*double-stranded RNA molecules  
*turn off gene expression by directing degradation of selective mRNA and the establishment of compact chromatin structures<br>
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*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 into 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]] in bacteria and miRNAs involved in [[RNAi]]&nbsp;(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>.  
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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>.  
  
 
== References  ==
 
== References  ==
  
 
<references />
 
<references />

Revision as of 15:07, 21 October 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 make up the backbone have a negative charge, which protects the molecule from being hydrolysed by 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. Like DNA, four nucleotide bases: cytosine (C), guanine (G), adenine (A) and uracil (DNA has a thymine base rather than uracil) 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].

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 synthesised 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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