Question

UAA, UAG and UGA are
A. Non-overlapping codons
B. Nonsense codons
C. Degenerate codons
D. Chain initiator codons

Answer 1

Codons are three-nucleotide sequences on the DNA which codes for a particular amino acid. UAA, UAG, and UGA stop codons and this means that they terminate the amino acid synthesis whenever they are translated. These codons have no specific tRNA for them.

Complete answer: The DNA or deoxyribonucleic acid is the genetic material present in the cell that assists cell functioning and protein synthesis. DNA is made of a series of thousands of nucleotides. Each nucleotide forms a part of a codon. Codons are the three-nucleotide framework that codes or translates into an amino acid. Codons are translated into mRNA transcripts which are then read by tRNA. The tRNA forms the translation unit along with ribosomes in the cytoplasm. This machine reads codons on mRNA. Each codon is translated into an amino acid. These amino acids are then joined together to form proteins. The chain initiator codon ‘AUG’ is the initiator of the protein synthesis process. It also synthesizes methionine amino acids. Degenerate codons refer to different triplet codons that code for a single or same amino acid. Non-overlapping codons are triplets that are read in a successive manner.
UAA, UAG, and UGA are nonsense codons; this means that they do not code for any amino acid. These are stop codons and terminate the protein synthesis process. Nonsense codons have no specific tRNA-Ribosomes translation machinery for their translation.
Therefore, option B is the correct answer.

Note: Stop codons are necessary to terminate the protein synthesis up to a specific length. Continuous protein synthesis will never let the protein chain become functional. Any disruptions in codon sequences can lead to genetic diseases.