Perceiving Order in the Makeup of the Code o 1. The genetic code evolved in such a way as to minimize the deleterious effects of mutations n 2. Code degeneracy may serve as o a safety mechanism to minimize errors in the reading of codons
Perceiving Order in the Makeup of the Code 1.The genetic code evolved in such a way as to minimize the deleterious effects of mutations. 2.Code degeneracy may serve as a safety mechanism to minimize errors in the reading of codons. The Code Is Degenerate
Detail 2: Code Degeneracy 1. The second position of a codon: a Pyrimidines-hydrophobic amino acids a Pure polar amino acids 2.If the first two positions are both occupied by G or c each of the four nucleotides in the third position specifies the same amino acid
Detail 2: Code Degeneracy 1.The second position of a codon: ◼ Pyrimidines-hydrophobic amino acids ◼ Purines-polar amino acids 2.If the first two positions are both occupied by G or C, each of the four nucleotides in the third position specifies the same amino acid
Wobble in the Anticodon Question: Is there a specific tRNA for 8 every codon? (If it was true, at least u 61 different tRNAs would exist n The answer is NO B> Some tRNA could recognize several different codons Inosine is present in the anticodon loop as a fifth base
Wobble in the Anticodon Question: Is there a specific tRNA for every codon? (If it was true, at least 61 different tRNAs would exist.) The answer is NO ➢ Some tRNA could recognize several different codons ➢ Inosine is present in the anticodon loop as a fifth base The Code Is Degenerate
Inosine H H N一H N一H bose N- ribose N H RosiN e adenine Inosine arises through enzymatic modification of adenine
Inosine inosine adenine Inosine arises through enzymatic modification of adenine
Wobble Concept In 1966, Francis crick devised the wobble concept. It states that the base at the 5 end of the anticodon is not as spatially confined as the other two, allowing it to form hydrogen bonds with more than one bases located at the 3 end of a codon
Wobble Concept In 1966, Francis Crick devised the wobble concept. It states that the base at the 5’ end of the anticodon is not as spatially confined as the other two, allowing it to form hydrogen bonds with more than one bases located at the 3’ end of a codon