is third base of codon doesn't specified for a single amino acids and which base is responsible for specification
The third base of a codon is not always specified for a single amino acid. This is because of a genetic phenomenon called "wobble" or degeneracy, which allows multiple codons to code for the same amino acid.
The third base of a codon is often referred to as the "wobble position" because it has less impact on the amino acid specified. In this position, there is flexibility, and certain non-standard base pairings can occur. This means that a single amino acid can be specified by multiple codons that differ only in their third base.
For example, the amino acid leucine can be specified by six different codons: UUA, UUG, CUU, CUC, CUA, and CUG. The first two bases of these codons are the same, while the third base varies, but they all code for leucine.
Therefore, the third base of a codon is responsible for providing flexibility in the genetic code, allowing different codons to specify the same amino acid.
The third base of a codon in DNA or RNA doesn't always specify a single amino acid directly. Instead, it often contributes to the degeneracy or redundancy of the genetic code, meaning that different codons can code for the same amino acid.
The specific base responsible for specifying an amino acid is the second base of the codon. This is known as the wobble base. The wobble base is usually located at the 5' end of the anticodon in transfer RNA (tRNA), which binds to the corresponding codon in the mRNA during translation.
The wobble base is capable of forming nonstandard interactions with the third base of the codon, allowing for flexibility in codon-anticodon pairing. This flexibility is known as the wobble hypothesis, proposed by Francis Crick in 1966. It allows a single tRNA molecule to recognize multiple codons that differ only at the third position.
For example, the codons GGC, GGU, GGA, and GGG all specify the amino acid glycine. The first two bases of these codons (GG) are kept constant, and it is the third base (C, U, A, or G) that can vary while still coding for glycine.
No, the third base of a codon is often referred to as the "wobble position" and does not always specify a single amino acid. The genetic code is redundant, meaning that multiple codons can code for the same amino acid. However, the first two bases of a codon generally play a more critical role in determining the amino acid sequence.
The base that is responsible for specifying the amino acid is usually the first base of the codon. The first base determines the major characteristic of the amino acid, while the second base can modify it to some extent. The third base, as mentioned, is less specific and can tolerate changes without affecting the amino acid encoded. This allows for some flexibility in the genetic code and helps protect against the negative effects of mutations.
To determine which base specifies a particular amino acid, you would need to consult a genetic code chart or table. These tables list all the possible codons and the corresponding amino acids they code for. By looking at the first base of a codon, you can find the amino acid it specifies.