The human genome contains approximately 20,000 protein-coding genes, yet it has the capacity to produce several hundred thousand gene products. What can account for the vast difference in gene number and product number?
◦ There are more introns than exons.
◦ Much of the DNA is in the form of trinucleotide repeats, thus allowing multiple start sites for different genes.
◦ Alternative splicing occurs.
◦ Every gene can be read in both directions, and each gene can have inversions and translocations.
◦ There are more exons than introns.