Final answer:
The UCSC Genome Browser's gene expression bar graph based on RNA-seq data reveals where and how much a gene is expressed across various tissues and cell lines, helping in the understanding of a gene's function and regulation.
Step-by-step explanation:
When analyzing gene expression levels using a platform like the UCSC Genome Browser, you'll come across a visualization tool that represents the median expression levels of genes across various tissues and cell lines, based on RNA-seq data from a substantial cohort of adults. This bar graph provides insights into where and how much a gene is expressed, which is fundamental to understanding its function and regulation in the human body.
The statement about the lung tissue (green) possibly having the greatest number of gene transcripts can be confirmed if the green bar representing lung tissue is one of the highest on the graph. If the brain (gray) bar shows greater height than that for adipose (orange), it would indicate more efficient transcription in the brain compared to adipose tissue. However, the differences in sequence reads across tissues are most likely indicative of differential gene expression, and not necessarily differences in gene copy number, which is generally constant across tissues of the same organism. As for liver (tan) and heart (purple), if these are depicted at different levels slightly to the right of the middle, it suggests that the gene in question is indeed expressed in both tissues but at differing levels.
Understanding gene expression is crucial as it helps determine the functional aspects of genes. Through technologies like RNA-seq, we can observe which genes are actively transcribed into mRNA and potentially translated into proteins in different tissues. This information is essential for biological research, especially when correlating gene activity with specific phenotypic traits, disease states or the effects of particular treatments.