The correct answer is Option 2: the full range of mRNA molecules expressed by an organism.

The term `transcriptome` is commonly used in the field of bioinformatics, which is the application of computational methods to analyze biological data. Specifically, the transcriptome refers to the complete set of messenger RNA (mRNA) molecules that are transcribed from DNA and expressed by an organism`s genome at a given time.

mRNA molecules play a crucial role in the process of gene expression, which is the mechanism by which genetic information stored in DNA is used to synthesize proteins, the functional units of cells. The transcriptome represents all the mRNA molecules that are actively being transcribed and translated into proteins in a specific cell, tissue, or organism at a particular moment in time. It provides valuable information about which genes are being expressed and to what extent, giving insights into the molecular processes that occur within cells and how they are regulated.

Transcriptome analysis has become a powerful tool in modern bioinformatics and has a wide range of applications, including studying gene function, identifying disease biomarkers, understanding developmental processes, and analyzing responses to environmental stimuli or drug treatments. High-throughput sequencing technologies, such as RNA-Seq, have revolutionized transcriptome analysis by enabling the simultaneous profiling of thousands of mRNA molecules in a single experiment, allowing researchers to obtain a comprehensive view of gene expression patterns.

It`s important to note that the transcriptome is distinct from the genome, which refers to the entire set of DNA sequences that make up an organism`s genetic material. While the genome contains all the genes that an organism possesses, the transcriptome represents the specific subset of genes that are actively being transcribed into mRNA molecules and translated into proteins. Therefore, Option 2 is the correct answer as it accurately describes the meaning and significance of the term `transcriptome` in the context of developments in bioinformatics.