Final answer:
The cells of organisms produce a variety of tRNA molecules, not just a few, and these tRNAs are crucial in translating mRNA sequences into proteins. The anticodon of each tRNA matches an mRNA codon and is linked to a specific amino acid, a key step in protein synthesis. The genetic code responsible for this process is nearly universal, signifying the common origin of life.
Step-by-step explanation:
The cells of every organism do not produce only a few different tRNA molecules; in fact, depending on the species, there can be 40 to 60 types of tRNA present in the cytoplasm. Each tRNA has a unique three-nucleotide anticodon that corresponds to an mRNA codon and a binding site for a specific amino acid. This specificity is critical because tRNAs are essentially the translators of the mRNA sequence into a protein sequence, a process known as translation. Moreover, the genetic code, which dictates the mRNA codon that corresponds to an amino acid, is nearly universal across all forms of life, showcasing the shared ancestry among different species.
Furthermore, each cell within an organism does not express all the genes encoded within its DNA; instead, it selectively transcribes genes into mRNA based on the cell's function and environmental signals. This selective gene expression results in the production of a specific subset of proteins in any given cell. The process begins with transcription, where genes are copied into mRNA, followed by translation, where tRNA molecules interpret the mRNA and facilitate the synthesis of proteins.
Regarding the tRNA variety, in eukaryotes, there are multiple copies of 40 to 50 tRNA types, which originate from longer RNA precursors. These precursors are processed enzymatically to produce functional tRNA molecules that participate in protein synthesis.