U01.01.005 Genetic code features

Definition: Each codon specifies only one amino acid.
Key Point: This ensures precision in the translation process, minimizing errors.

Definition: Most amino acids are coded by multiple codons.
Wobble Hypothesis:
- Codons that differ in the 3rd (“wobble”) position may code for the same tRNA/amino acid.
- Specific base pairing is usually required only in the first 2 nucleotide positions of the mRNA codon.
Exceptions:
- Methionine (AUG) and tryptophan (UGG) are encoded by only one codon.

Definition: The genetic code is read from a fixed starting point as a continuous sequence of bases.
Key Point: Ensures that codons are read sequentially without overlapping.
Exceptions:
- Some viruses deviate from this rule.

Definition: The genetic code is conserved throughout evolution.
Key Point: Highlights the universality of the genetic code across different organisms.
Exception in Humans:
- Mitochondria have a slightly different genetic code.

Feature	Description	Exceptions
Unambiguous	Each codon specifies only one amino acid	None
Degenerate/Redundant	Most amino acids are coded by multiple codons	Methionine (AUG), Tryptophan (UGG)
Wobble Hypothesis	Codons differing in the 3rd position may code for the same tRNA	None
Commaless, Nonoverlapping	Read as a continuous sequence from a fixed starting point	Some viruses
Universal	Conserved throughout evolution	Human mitochondria

Precision: The unambiguous nature ensures that each codon corresponds to one specific amino acid.
Flexibility: Degeneracy allows for some mutations to be silent, reducing the impact on protein function.
Reading Frame: Commaless and nonoverlapping code maintains the integrity of the reading frame.
Evolutionary Conservation: The universality underscores the shared genetic heritage of all life forms, with minor exceptions like mitochondrial DNA in humans.

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