Final answer:
Plant and animal cells have approximately 40 to 50 different species of transfer RNA, encoded by repeated DNA sequences. tRNAs are crucial for translating the mRNA into proteins. Despite early estimates of a larger number of genes, the human genome has only about 20,000 to 25,000 genes with plenty of non-coding DNA for other functions, including tRNA formation.
Step-by-step explanation:
Plant and animal cells are estimated to have approximately 40 to 50 different species of transfer RNA (tRNA), each encoded by a repeated DNA sequence. In eukaryotic cells, such as those of plants and animals, tRNAs are essential for protein synthesis. Each tRNA type corresponds with specific amino acids and anticodons, contributing to the translation of mRNA into protein. Even though early estimates proposed around 100,000 genes for organisms such as humans, mice, and petunias, current knowledge indicates that humans have between 20,000 to 22,000 genes. Despite this, the human genome consists of much more DNA than needed for these genes, suggesting that many sequences contribute to functions beyond encoding proteins, including the regulation of gene expression and the formation of tRNA.
Bacterial tRNA species also show diversity with approximately 60 to 90 species existing, demonstrating that a significant amount of genetic material is dedicated to the process of translation across different domains of life. The actual number of tRNA species can slightly vary between different organisms depending on their specific genetic and metabolic needs.