Difficulty in Defining a Gene in Terms of DNA Sequences

Defining a gene in terms of DNA sequences is a challenging task due to the following reasons:

1. Complex Genome Structure

The genome structure of most organisms is highly complex, with many genes overlapping each other and having multiple functions. This makes it difficult to define a gene in terms of a specific DNA sequence.

2. Alternative Splicing

Many genes undergo alternative splicing, which results in the production of multiple protein isoforms from a single gene. This further complicates the task of defining a gene in terms of its DNA sequence.

3. Non-Coding DNA

A significant portion of the genome consists of non-coding DNA sequences that do not code for proteins. These regions are still thought to have important regulatory functions, and it is difficult to classify them as part of a gene in terms of DNA sequences.

Example: The Human Genome

The human genome is an excellent example of the difficulty in defining a gene in terms of DNA sequences. The human genome contains approximately 20,000-25,000 protein-coding genes, but these genes make up only about 2% of the entire genome. The rest of the genome consists of non-coding DNA sequences, including introns, regulatory regions, and repetitive sequences.

Furthermore, many genes in the human genome undergo alternative splicing, resulting in the production of multiple protein isoforms. For example, the gene for the protein dystrophin, which is mutated in muscular dystrophy, has 79 exons that can be spliced in different combinations to produce up to 2,200 different protein isoforms.

Conclusion

In conclusion, defining a gene in terms of DNA sequences is a challenging task due to the complex structure of the genome, alternative splicing, and the presence of non-coding DNA sequences. However, advances in genome sequencing technology and bioinformatics tools are continually improving our understanding of gene structure and function.

Actually I did have the same thing as u but... DNA is a whole stretch of the chromosomes but genes are only a small part of it.. maybe u should check out gene mapping it will really help u out...
GENE---A distinct sequence of DNA by which offspring inherit parental characters....
Another way to put it is Gene is smthg that codes for a trait and DNA(the whole length of it) doesn't.....
I really hope u get it cuz with this confusion it's gonna be hard....