Zoology · Ch 10 — Applications of Biotechnology
Human Growth Hormone (hGH)
Human Growth Hormone (hGH)
Human growth hormone (hGH), along with the related peptide hormones somatostatin and somatotropin, is secreted by the pituitary gland and drives growth and development by increasing amino-acid uptake and protein synthesis in tissues. A deficiency in childhood causes dwarfism, historically treated by injecting hGH extracted from cadaver pituitary glands — a supply that was both scarce and, it later emerged, occasionally contaminated. Recombinant DNA technology removed both problems: the hGH gene is isolated from human pituitary cells and, using a restriction enzyme such as EcoRI to cut a bacterial plasmid at matching sticky ends, is spliced into the plasmid to form recombinant DNA. This recombinant plasmid is introduced into E. coli, which is then cultured and mass-produced by fermentation; the resulting recombinant hormone, marketed as somatropin, …
What this figure shows. A two-part schematic of hGH manufacture. On the left, a human cell contributes the gene for human growth hormone; on the right, a bacterial cell's plasmid is opened at its sticky ends using the restriction enzyme EcoRI (the bacterial chromosome is shown separately, untouched). The isolated hGH gene and the cut-open plasmid undergo DNA recombination (the gene is inserted into the plasmid) to form recombinant DNA. This recombinant plasmid is then reintroduced by DNA insertion into a bacterial cell, producing a bacterial cell that now carries and expresses the gene for human …