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Download Lecture 8: Reproductive hormones and sexual maturation
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Fig. 10.1 1 Table 10.1a Table 10.1b 2 Action of a steroid hormone Fig. 10.15 So alike and yet so different… different… The magic is in the side chain! 3 Steroid hormones Slide number: 1 Steroid hormone Newly forming protein molecule Cell membrane Ribosome mRNA Nucleus mRNA Intracellular protein receptor DNA Hormone-receptor complex Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Steroid hormones Slide number: 2 Steroid hormone Cell membrane Nucleus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 4 Steroid hormones Slide number: 3 Steroid hormone Cell membrane Nucleus Intracellular protein receptor Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Steroid hormones Slide number: 4 Steroid hormone Cell membrane Nucleus mRNA Intracellular protein receptor DNA Hormone-receptor complex Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 5 Steroid hormones Slide number: 5 Steroid hormone Cell membrane Nucleus mRNA Intracellular protein receptor DNA Hormone-receptor complex Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Steroid hormones Slide number: 6 Steroid hormone Newly forming protein molecule Cell membrane Ribosome mRNA Nucleus mRNA Intracellular protein receptor DNA Hormone-receptor complex Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 6 Action of a peptide hormone Steroid versus peptide hormones Steroid: Steroid: passes through cell membrane, possibly nuclear membrane, then binds to receptor protein to alter DNA transcription Peptide: Peptide: binds to cell membrane receptor, triggers downstream cascade of signal transduction activating enzyme cascade 7 Examples of chemical signaling Long distance communication is possible with hormones Effects of hypothalamus and pituitary 8 Negative feedback regulation loop Development of male versus female organs • same structures at six weeks • by 14 weeks differences are clearly evident • Y chromosome leads to testosterone production and development of testes • development of external genitalia parallels internal changes • later sexual maturation in puberty is tied to melatonin production 9 The SRY gene • sex-determining region of Y • demonstrated by linkage analyses of XX males and XY females - in both cases the region coding for SRY was altered. • if SRY present - male • if SRY absent - female • no gene for female gender determination • a transcription factor - turns on multiple genes leading to development of male phenotype Does biology influence sexual orientation? 10 The pineal gland and melatonin production Regulation of testosterone level in males 11 Regulation of estrogen levels in females Effects of anabolic steroid use - dangerous! 12 Hormone replacement therapy (HRT): Jury’ Jury’s out 13
