Question

1. Read the following paragraph:

“The human genome sequence provides the underlying code for human biology. Despite intensive study, especially in identifying protein-coding genes, our understanding of the genome is far from complete, particularly with regard to non-coding RNAs, alternatively spliced transcripts and regulatory sequences. Systematic analyses of transcripts and regulatory information are essential for the identification of genes and regulatory regions and are an important resource for the study of human biology and disease. Such analyses can also provide comprehensive views of the organization and variability of genes and regulatory information across cellular contexts, species and individuals. The Encyclopedia of DNA Elements (ENCODE) project aims to delineate all functional elements encoded in the human genome. Operationally, we define a functional element as a discrete genome segment that encodes a defined product (for example, protein or non-coding RNA) or displays a reproducible biochemical signature (for example, protein binding, or a specific chromatin structure).” ENCODE Project Consortium (2012) An integrated encyclopedia of DNA elements in the human genome Nature 489:57074.

Consider the ENCODE definition of gene. What did you learn regarding the diversity of human physiognomy and physiology (both “normal” and pathologies) based on the genetic composition and gene expression in humans?

Answer 1

Gene is a complex unit of DNA. The ENCODE definition of gene is simple, which states that the "discrete genome segment that encodes a defined product or displays a reproducible biochemical signature". This definition covers both protein-coding genes as well as the RNA coding and non-coding but regulatory genes.

• The complexity arises because the majority of genes in the human body do not code for a protein, they are non-coding or code of RNA, thus involved in regulatory mechanisms.
• The diversity of human physiology is so vast that gene expressions and functions vary according to body state and pathogenesis - due to alternate splice, regulatory RNA molecules,...etc.
• Identifying correct genes responsible for physiological activities is important from a health perspective.
• We need to know and understand the working of pathogenic genes and how they can infect and cause diseases - how pathogenic genes are combined in the human genome and code for pathogenic proteins like in viruses.
• It is also important to identify the genes involved in the immune response against specific pathogens so that we can design better treatments.