Final answer:
The traits of an organism are determined by its genes, which are segments of DNA containing instructions for synthesizing proteins. These proteins' structure and function, dictated by the sequence of amino acids, contribute to the organism's characteristics according to the Central Dogma of Molecular Biology.
Step-by-step explanation:
The Determinants of Organism Traits
Organism traits are determined by the specific combination of inherited genes. These genes are segments of DNA, or deoxyribonucleic acid, that contain the encoded instructions necessary to synthesize proteins. Each gene's sequence of nucleotides in the DNA - consisting of cytosine, thymine, adenine, and guanine - instructs the creation of proteins, which are vital for the structure and function of all the cells within an organism. Proteins' structures are dictated by their amino acid sequences, which are in turn coded for by the DNA within the gene specific for that protein. The unique combination of amino acids in a protein influences how it folds and functions, thus affecting the organism's traits.
The Central Dogma of Molecular Biology outlines the flow of genetic information from DNA to RNA to proteins. It is this process that underpins the conversion of the genetic blueprint into tangible traits. Ultimately, the vast diversity of life on Earth can be attributed to the variations in the genetic code of every living being.
Therefore, addressing the original question, the correct determinant of the traits of an organism is: A. the sequence of nucleotides in the DNA.