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Why are there multiple start codons?
All Answers (4) Dear Aqib Sayyed, It’s common to have multiple ATG codons in an mRNA sequence. This is because the specific motifs and structures of the mRNA sequence has to be integrated correctly into a ribosome, a protein translation machinery, to initiate the translation process.
Is there only one start codon?
The fact that there exists only one start codon AUG in the standard genetic code (see Table 1) has also a certain evolutionary advantage, since the number of positions, from where the genetic information is read, is minimal.
How many start codons are in a gene?
The standard genetic code table contains one start codon, AUG. Over the years, however, many studies have demonstrated that alternative start codons, such as GUG, could be utilized for translation initiation with non-negligible frequencies, i.e. up to 20\% non-AUG starts1,2.
How do you find the start codon?
Start codon
- The start codon is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome.
- The start codon is often preceded by a 5′ untranslated region (5′ UTR).
- Alternative start codons are different from the standard AUG codon and are found in both prokaryotes (bacteria and archaea) and eukaryotes.
Are there multiple start and stop codons in a DNA sequence?
2 Answers 2. Whether or not there are multiple start and stop codons depends on what you mean by “start codon” and “stop codon”. The start codon has the sequence “AUG”, and the stop codon has the sequence “UAG”, “UAA”, or “UGA”.
How many codons are there in the genetic code?
The genetic code can be read in multiple ways depending on where the reading starts. For example, if the base sequence is GGGAAACCC, reading could start from the first letter, G and there will be 3 codons – GGG, AAA, and CCC. If reading starts at G in the second position, the string will have two codons – GGA and AAC.
Can you have more than one AUG codon in mRNA?
However, the universal start codon in most eukaryotes is also the codon for the amino acid methionine, so you can certainly have more than one “AUG” codons in your mRNA, it’ll just include a methionine in the middle of the chain rather than starting a new one. What does Google know about me?
What are the different types of start codons in translation?
Apart from the usual Met codon, mammalian cells can also START translation with the amino acid leucine with the help of a leucyl-tRNA decoding the CUG codon. Mitochondrial genomes use AUA and AUU in humans and GUG and UUG in prokaryotes as alternate START codons.