Main articles: Growth hormone 1 and Growth hormone 2. Genes for human growth hormone, known as growth hormone 1 (somatotropin) and growth hormone 2, are localized in the q22-24 region of chromosome 17 and are closely related to human chorionic somatomammotropin (also known as placental lactogen) genes.
Average costs are U-shaped, and the marginal cost curve intersects the average cost curves at their respective minimum points. In the competitive model of the firm, the minimum average variable cost is termed the shutdown point because a firm will not produce in the short run if price is below average variable cost.
For a perfectly competitive firm with no market control, the marginal revenue curve is a horizontal line. Because a perfectly competitive firm is a price taker and faces a horizontal demand curve, its marginal revenue curve is also horizontal and coincides with its average revenue (and demand) curve. For firms with more market control, especially monopoly, the average revenue curve is negatively-sloped.