RNA: Difference between revisions
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RNA stands for ribonucleic acid. It 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. Unlike [[DNA]], RNA has a ribose sugar, which means that it has a 2` [[ | RNA stands for ribonucleic acid. It 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. Unlike [[DNA]], RNA has a [[Ribose|ribose]] sugar, which means that it has a 2` [[Hydroxyl group|hydroxyl group]]. | ||
Attached to the backbone are 4 [[Base|bases]], in a similar way to DNA, in which [[Cytosine|cytosine]] (C) pairs with [[Guanine|guanine]] (G) and [[Thymine|thymine]] (T) pairs with [[Adenine|adenine]] (A). However in RNA C pairs with G, but A pairs with uracil (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> | Attached to the backbone are 4 [[Base|bases]], in a similar way to DNA, in which [[Cytosine|cytosine]] (C) pairs with [[Guanine|guanine]] (G) and [[Thymine|thymine]] (T) pairs with [[Adenine|adenine]] (A). However in RNA C pairs with G, but A pairs with [[uracil|uracil]] (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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- 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 in the cytoplasm<br> - This mRNA is then used as a template for [[Translation|translation]] into a functional protein<br> - mRNA is 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 mRNA is then used as a template for [[Translation|translation]] into a functional protein<br> - mRNA is also used to make copy DNA ([[CDNA|cDNA]]) | ||
<br>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> | <br>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 a clover shape, held together by [[Hydrogen bonds|hydrogen bonds]]<br> - Consists of a specific sequence of three unpaired bases bound to a complementary codon ([[Anticodon|anticodon]]) and | - Single polynucleotide strand which is folded into a clover shape, held together by [[Hydrogen bonds|hydrogen bonds]]<br> - Consists of a specific sequence of three unpaired bases bound to a complementary [[codon|codon]] ([[Anticodon|anticodon]]) and an [[Amino_acid|amino acid]] binding site | ||
- Found in the 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]]. | ||
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<br>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><br> - This is the RNA which forms [[Ribosomes|ribosomes]]<br> - It acts as a catalyst for [[Proteins|protein]] synthesis | <br>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><br> - This is the RNA which forms [[Ribosomes|ribosomes]]<br> - It acts as a catalyst for [[Proteins|protein]] synthesis | ||
- It is synthesised in the nucleolus | - It is synthesised in the [[Nucleolus|nucleolus]] | ||
- rRNA molecules do not code for protein | - rRNA molecules do not code for protein | ||
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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. | 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]]. | ||
RNA can also exist in non coding forms. These non coding RNAs have many applications but many revolve around regulation of 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 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 20:28, 23 December 2011
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)
- 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.
RNA can also exist in non coding forms. These non-coding RNAs 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
- ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 109
- ↑ Lyons, I, 2011. Biomedical Science Lecture Notes. 1st ed. Oxford: Wiley-Blackwell, p21-23
- ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 119
- ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120
- ↑ Berg JM, Tymoczko JL and Stryer L, 2007, Biochemistry 6th edition, NY, W. H Freeman and Company, page 120
- ↑ 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