Molecular Definition of a Gene
■ In molecular terms, a gene is the entire DNA sequence required for synthesis of a functional protein or RNA molecule. In addition to the coding regions (exons), a gene includes control regions and sometimes introns.
■ Most bacterial and yeast genes lack introns, whereas most genes in multicellular organisms contain introns. The total length of intron sequences often is much longer than that of exon sequences.
■ A simple eukaryotic transcription unit produces a single monocistronic mRNA, which is translated into a single protein.
■ A complex eukaryotic transcription unit is transcribed into a primary transcript that can be processed into two or more different monocistronic mRNAs depending on the choice of splice sites or polyadenylation sites (see Figure 10-2b).
■ Many complex transcription units (e.g., the fibronectin gene) express one mRNA in one cell type and an alternative mRNA in a different cell type.
Was this article helpful?
Discover secrets, myths, truths, lies and strategies for dealing effectively with cholesterol, now and forever! Uncover techniques, remedies and alternative for lowering your cholesterol quickly and significantly in just ONE MONTH! Find insights into the screenings, meanings and numbers involved in lowering cholesterol and the implications, consideration it has for your lifestyle and future!