Question

Start and stop codons are
A.AUG and UGA
B.GUA and AAA
C.UCA and UAA
D.GCA and AUG

Answer 1

The genetic code is the sequence of nucleotides, in ribonucleic acid and deoxyribonucleic acid that determine the amino acid sequence of proteins. It is discussed using codons found in mRNA that carry information from the DNA protein synthesis takes place.

Complete step by step answer: The genetic code is largely invariant throughout the extent of all species, therefore it is referred to as the conical or Universal genetic code. There is a deviation in both the cell organelle and nuclear genomes and they are known as non- canonical or deviant codes. Genetic code is the set of rules which dictate the linear sequence of nucleotides in the linear sequence of polypeptides. It specifies how a nucleotides sequence of an mRNA is translated into the amino acids.
The stop codon is also called nonsense codons. They do not code for any amino acid. In a DNA molecule, there are four nitrogenous bases namely A, G, T, and C. The specific sequence of these four bases in the DNA strand determines the sequence of amino acids in a protein molecule. In the process of protein synthesis tRNA plays the role of an adapter. One part of the tRNA binds to a specific amino acid and the other part recognizes the nucleotides sequence encoding that amino acid in the mRNA.
Codons are the nucleotide bases triplets that specify a particular amino acid in the protein. The stop codons are UAG, UAA, and UGA. The start codon specifies the First codon of mRNA transcript that is translated by a ribosome. It codes for methionine in eukaryotes and a modified met in Prokaryotes. “AUG” is the most common start codon. AUG and UGA are the start and stop codons respectively.
Thus, the answer is option A: AUG and UGA

Note: Stop codons are known by different names. UAA is known as ochre, UGA as opal, and UAG as amber. A specific first codon in the sequence establishes the reading frame of the genetic message. This is known as the initiation codon, and it codes for the amino acid methionine.