Which codons correspond to which amino acids?
Inverse DNA codon table
| Amino acid | DNA codons | Amino acid |
|---|---|---|
| Gln, Q | CAA, CAG | Ser, S |
| Glu, E | GAA, GAG | Thr, T |
| Gln or Glu, Z | CAA, CAG; GAA, GAG | Trp, W |
| Gly, G | GGT, GGC, GGA, GGG | Tyr, Y |
How the genetic code provides instructions for building proteins?
Genes that provide instructions for proteins are expressed in a two-step process.
- In transcription, the DNA sequence of a gene is “rewritten” using RNA nucleotides.
- In translation, the sequence of nucleotides in the mRNA is “translated” into a sequence of amino acids in a polypeptide (protein or protein subunit).
How many codons are needed to specify amino acids?
The cell reads the sequence of the gene in groups of three bases. There are 64 different codons: 61 specify amino acids while the remaining three are used as stop signals.
Which is the initiation codon where is it present?
AUG
Correct answer- C. Explanation: AUG codes for methionine and also serves as the initiation codon, when present as the first mRNA codon.
How many amino acids does each codon code for?
Each codon codes only for one specific amino acid. The codes are universal irrespective of the type of organism, i.e. CGU would code for Arginine in animals as well as in bacteria but exceptions exist.
How do I memorize the codon triplet?
Remember that a mutation in third nucleotide in the codon triplet has less effect in changing the amino acid than the first two. Leverage this information to memorize. For example, see the figure below. You don’t have to. Just learn the start codon and 3 stop codons.
How many codons act as initiator codons?
Out of 64 codons, 3 are stop codons which do not code for any amino acids and thus ends the process of translation. AUG coding for Methionine is the only codon that acts an initiator codon.
Why do some amino acids have more than one code?
Some amino acids are coded by more than one codon thus making them to degenerate. Each codon codes only for one specific amino acid. The codes are universal irrespective of the type of organism, i.e. CGU would code for Arginine in animals as well as in bacteria but exceptions exist.