Final answer:
A few overlapping genes may exist, but in general, codons do not overlap within a gene, and the genetic code is non-overlapping. The near-universal genetic code involves triplets of nucleotides called codons that specify amino acids, and the process is continuous with no shared nucleotides between codons. Introns and exons in eukaryotes add complexity by segmenting the coding sequence, but only exons contribute to protein synthesis.
Step-by-step explanation:
A few overlapping genes are found in various organisms, but codons within the same gene do not overlap, and the genetic code is generally considered to be non-overlapping. The idea of overlapping codons was once considered as a way to achieve genomic economies. However, it was quickly understood that this concept was untenable because it imposes unrealistic restrictions on the sequence of amino acids. For example, if codons overlapped by two bases, each ensuing amino acid would need to start with a specific base, which does not align with the fact that virtually any amino acid can follow another. The genetic code must therefore be non-overlapping.
The genetic code is a set of rules that relate nucleotide sequences to the amino acids they encode. Each codon, composed of three nucleotides in a row, is translated into a specific amino acid during the process of protein synthesis. This is a continuous and non-overlapping process, meaning that no single nucleotide is shared between adjacent codons. Additionally, the genetic code is near-universal, indicating a common origin of life on Earth, with only minor variations observed across different species.
In eukaryotes, the presence of introns and exons within genes complexifies the structure of genetic information. This arrangement means that not all DNA sequences in a gene are translated into protein. The exons are the coding sequences that are ultimately expressed, while introns are non-coding and do not contribute to the amino acid sequence of proteins.