Wobble base pair - Wikipedia
Among the most frequent of wobble base pairs are G · T(U) base pairing (“ wobble base”) and the corresponding 5′ nucleotide of the tRNA anticodon (15). ], as well as giving evidence for the relationship between tRNA species copy Crick initially proposed the wobble rules based on the observation that He guessed that the first position of the tRNA anticodon could base pair with more. Structure and roles of transfer RNAs and ribosomes. Codons, anticodons, and wobble. Aminoacyl-tRNA synthetases.
Wobble base pair
Translation then proceeds in the new reading frame to complete synthesis of RF 2 2 regulates its own synthesis in a feedback loop. An especially unusual frameshifting mechanism occurs through the editing of mRNAs prior to translation.
The genes in mitochondrial DNA that encode the cytochrome oxidase subunit II in some protists do not have open reading frames that correspond precisely to the protein product. Instead, the codons specifying the amino terminus of the protein are in a different reading frame from the codons specifying the carboxyl terminus.What Is Wobble Hypothesis - Molecular Basis of Inheritance - Biology Class 12
The problem is corrected not on the ribosome, but by a posttranscriptional editing process in which four uridines are added to create three new codons and shift the reading frame so that the entire gene can be translated directly, as shown in Figure 2a; the added uridine residues are shown in red.
Only a small part of the gene the region affected by editing is shown. Neither the function nor mechanism of this editing process is understood. A special class of RNA molecules encoded by these mitochondria have been detected that have sequences complementary to the final, edited mRNAs. These appear to act as templates for the editing process and are referred to as guide RNAs Fig.
Figure 1 The gag pol overlap region in Rous sarcoma virus. Figure 2 RNA editing of the transcript of the cytochrome oxidase subunit II gene from mitochondria of Trypanosoma brucei. A distinct form of RNA editing occurs in the gene for the apolipoprotein B component of lowdensity lipoprotein in vertebrates.
One form of apo lipoprotein B, called apoB Mr, is synthesized in the liver. A second form, apoB M. Both are synthesized from an mRNA produced from the gene for apoB The apoB produced in the intestine from the modified mRNA is simply an abbreviated form corresponding to the amino-terminal half of apoB Fig.
The rules of wobble pairing ensure that a tRNA does not bind to the wrong codon. These codons specify leucine, not phenylalanine, so this is an example of how the rules of wobble pairing allow a single tRNA to cover multiple codons for the same amino acid, but don't introduce any uncertainty about which amino acid will be delivered to a particular codon.
Image modified from " Translation: You may be wondering: The answer may be that wobble pairing allows fewer tRNAs to cover all the codons of the genetic code, while still making that the code is read accurately. The 3D structure of a tRNA I like to draw tRNAs as little rectangles, to make it clear what's going on and to have plenty of room to fit the letters of the anticodon on there. But a real tRNA actually has a much more interesting shape, one that helps it do its job. However, the strand takes on a complex 3D structure because base pairs form between nucleotides in different parts of the molecule.
This makes double-stranded regions and loops, folding the tRNA into an L shape. Each nucleotide consists of a five-carbon sugar, one or more phosphate groups, and a nitrogenous base. DNA has four types of nucleotides, each with a different nitrogenous base.
RNA also has four types of nucleotides. These nucleotides are similar to those of DNA, but contain a different sugar.
Wobble Hypothesis - The School of Biomedical Sciences Wiki
Certain types of nucleotides can form hydrogen bonds with one another. These nucleotides can hydrogen bond with one another because their structures are complementary — that is, they fit together like chemical puzzle pieces. Mutation[ edit ] A synonymous codon is one that, despite a small mutation, codes for the same amino acid. In the case of leucineit has six codons that it will respectively identify as leucine, so if the original codon on the DNA sequence was C-U-A and there was a small mutation in the DNA sequence that led to a C-U-U codon, then leucine would still recognize that codon and translate the mRNA transcript.
Codons in that sense are said to be synonymous. Occasionally, if one uses the last example of leucine one sees that if the C-U-A codon is changed to U-U-A it still codes for leucine. These would also be synonymous codons and show that even a base as important as the first can be changed, and because of Wobble the same amino acid anticodon will still be paired with the resulting codon. If the mutation is for an amino acid with similar qualities, such as hydrophobic or polar tendencies, then there is a strong possibility that the resulting protein will resemble much of the same structure.
- Wobble Hypothesis
- There was a problem providing the content you requested
- tRNAs and ribosomes