RNA: Difference between revisions
From Proteopedia
Jump to navigationJump to search
No edit summary |
No edit summary |
||
| Line 10: | Line 10: | ||
===Genetic information=== | ===Genetic information=== | ||
RNA plays key roles in gene expression, in the form of mRNA (messenger RNA), tRNA (transfer RNA) and rRNA (ribosomal RNA), the classic three types of RNA. Beyond these roles, RNA also serves to store genetic information and to regulate and modulate it. | RNA plays key roles in gene expression, in the form of mRNA (messenger RNA), tRNA (transfer RNA) and rRNA (ribosomal RNA), the classic three types of RNA. Beyond these roles, RNA also serves to store genetic information and to regulate and modulate it. | ||
====Storage==== | ====Storage==== | ||
Human immunodeficiency virus carries genetic information in the form of single stranded RNA. In the figure, the RNA is located in the dark spots inside the circular virus particles [[Image:HIV_particles.JPG|thumb]] | Human immunodeficiency virus carries genetic information in the form of single stranded RNA. In the figure, the RNA is located in the dark spots inside the circular virus particles [[Image:HIV_particles.JPG|thumb]] | ||
====Transcription==== | ====Transcription==== | ||
RNA is synthesized by RNA polymerases using DNA (or sometimes RNA) as a template. During synthesis, the template and the newly synthesized RNA form a base-paired, anti-parallel structure. Shown here is the <scene name='49/491851/Transcription/1'>initiation of transcription by phage T7 RNA polymerase</scene> (<jmol><jmolLink><script> select rna; selectionHalos ON; delay 0.5;selectionHalos OFF;</script><text>⚞RNA⚟</text></jmolLink> </jmol>) | RNA is synthesized by RNA polymerases using DNA (or sometimes RNA) as a template. During synthesis, the template and the newly synthesized RNA form a base-paired, anti-parallel structure. Shown here is the <scene name='49/491851/Transcription/1'>initiation of transcription by phage T7 RNA polymerase</scene> (<jmol><jmolLink><script> select rna; selectionHalos ON; delay 0.5;selectionHalos OFF;</script><text>⚞RNA⚟</text></jmolLink> </jmol>) <ref>PMID:19811903</ref> | ||
====Post-transcriptional modification==== | ====Post-transcriptional modification==== | ||
Introns are segments of RNA that have catalytic activity. These elements can splice RNA (remove the intron) and sometimes act as retrotransposons (i.e. they can insert themselves into pieces of RNA, which then - via reverse transcription - changes the sequence of DNA). The <scene name='49/491851/Intronii/2'>class IIc intron</scene> shown here in complex with a small piece of its substrate (the exon) catalyzes phophodiester transesterification using bound magnesium ions. | Introns are segments of RNA that have catalytic activity. These elements can splice RNA (remove the intron) and sometimes act as retrotransposons (i.e. they can insert themselves into pieces of RNA, which then - via reverse transcription - changes the sequence of DNA). The <scene name='49/491851/Intronii/2'>class IIc intron</scene> shown here in complex with a small piece of its substrate (the exon) catalyzes phophodiester transesterification using bound magnesium ions.<ref>PMID:18953333</ref> | ||
====Translation==== | ====Translation==== | ||
Ribosomes synthesize proteins with sequences determined by mRNA. The ribosome is a complex of rRNA and protein. Shown here is a small part of the ribosome illustrating protein-RNA interactions: <scene name='49/491851/Ribosomal/1'>ribosomal RNA</scene> (<jmol><jmolLink><script> select rna; selectionHalos ON; delay 0.5;selectionHalos OFF;</script><text>⚞RNA⚟</text></jmolLink> </jmol>). When synthesizing proteins, ribosomes follow the genetic code to translate an RNA sequence (grouped into codons of 3 nucleotides) into a protein sequence.<scene name='43/433638/Wireframe/5'>tRNAs</scene> are the adapter molecules that embody the genetic code. Each tRNA is covalently bound to a specific amino acid at one end and display an anti-codon on the other end (for more details, see [[transfer RNA]]) | Ribosomes synthesize proteins with sequences determined by mRNA. The ribosome is a complex of rRNA and protein. Shown here is a small part of the ribosome illustrating protein-RNA interactions: <scene name='49/491851/Ribosomal/1'>ribosomal RNA</scene> (<jmol><jmolLink><script> select rna; selectionHalos ON; delay 0.5;selectionHalos OFF;</script><text>⚞RNA⚟</text></jmolLink> </jmol>). When synthesizing proteins, ribosomes follow the genetic code to translate an RNA sequence (grouped into codons of 3 nucleotides) into a protein sequence.<scene name='43/433638/Wireframe/5'>tRNAs</scene> are the adapter molecules that embody the genetic code. Each tRNA is covalently bound to a specific amino acid at one end and display an anti-codon on the other end (for more details, see [[transfer RNA]]) | ||
===Catalysis=== | ===Catalysis=== | ||
In addition to the examples of catalytic RNA already mentioned in the previous section (ribosome, introns), other ribozymes exist. | In addition to the examples of catalytic RNA already mentioned in the previous section (ribosome, introns), other ribozymes exist. | ||
