There used to be 100,000 genes in the human genome. That is, until technology improved and scientists could make more accurate predictions. It is now believed that there are somewhere in the region of 20,000-25,000 human genes.
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So a rather large handful of genes go into making you and me. They can be found inside cells, and are unevenly distributed across our 46 chromosomes. Each chromosome contains regions that are rich in genes and portions where they are much fewer in number.
Genes code for proteins, that is they provide the instructions for proteins to be made. It has been estimated that only 1.5% of the human genome consists of protein coding sequences, known as exons. Introns are non-coding regions of genes.
Gene expression is where the information locked up inside a gene is used to synthesize a protein product. The process is controlled by several regulatory elements such as transcription factors which bind to DNA.
That the total number of genes has been revised down continually over the years is intriguing. We are incredibly complex beings and as our genes are relatively few in number scientists believe that this puts the onus on gene regulation.
It could mean that some genes have more than one function and this is determined each time by how it is regulated. What that means is that our complexity and diversity is not just governed by the DNA sequences that make genes, but also the gaps between these genes that control what they do.
The DNA that's 'hiding' between these human genes is increasingly finding itself under the spotlight as more research teams are probing these areas of the human genome to understand how our bodies are built and function at the molecular level.
The more we understand about human genes the better our chances of diagnosing and defeating serious diseases such as cancer. We will soon be moving into the era of personalized medicine where one day an individual might have a print out of his or her own personal genome. Medicines have different effects on people, largely due to differences such as single nucleotide polymorphisms (SNPs) and a personalized genome should help doctors tailor specific treatments to patients. Technological advances from the $1000 dollar genome race will make this goal more achievable and less of a fantasy idea.