1. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Chemistry of Hormones  Two mechanisms in which hormones act:  Direct gene activation  Lipid – soluble hormones (steroid hormones)  Second-messenger system  Water – soluble hormones (protein & peptide hormones)

2. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Direct Gene Activation (Steroid Hormone Action) Steroidal Hormones (lipid - soluble)...  1. Diffuse through the plasma membrane of target cells  2. Enter the nucleus  3. Bind to a specific protein receptor within the nucleus  4. Hormone/receptor complex binds to specific sites on the cell’s DNA  5. Binding activates genes that transcribe mRNA  6. mRNA is translated in cytoplasm, resulting in synthesis of new proteins

3. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1a Nucleus Cytoplasm Steroid hormone Receptor protein Hormone-receptor complex DNA mRNA New protein Plasma membrane of target cell

4. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1a, step 1 Nucleus Cytoplasm Steroid hormone Plasma membrane of target cell

5. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1a, step 2 Nucleus Cytoplasm Steroid hormone Plasma membrane of target cell

6. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1a, step 3 Nucleus Cytoplasm Steroid hormone Receptor protein Hormone-receptor complex Plasma membrane of target cell

7. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1a, step 4 Nucleus Cytoplasm Steroid hormone Receptor protein Hormone-receptor complex DNA Plasma membrane of target cell

8. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1a, step 5 Nucleus Cytoplasm Steroid hormone Receptor protein Hormone-receptor complex DNA mRNA Plasma membrane of target cell

9. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1a, step 6 Nucleus Cytoplasm Steroid hormone Receptor protein Hormone-receptor complex DNA mRNA New protein Plasma membrane of target cell

10. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Second-Messenger System (Nonsteroid Hormone Action) Protein & Peptide Hormones (water - soluble)...  1. Hormone binds to a membrane receptor (Hormone does not enter the cell)  2. Activated receptor sets off a series of reactions that activates an enzyme  3. Enzyme catalyzes a reaction that produces a second-messenger molecule  Ex: cAMP, cGMP, calcium ions  4. Second-messenger molecule oversees additional intracellular changes to promote a specific response

11. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1b Cytoplasm Nonsteroid hormone (first messenger) Enzyme Receptor protein Second messenger Effect on cellular function, such as glycogen breakdown Plasma membrane of target cell ATP cAMP

12. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1b, step 1 Cytoplasm Nonsteroid hormone (first messenger) Receptor protein Plasma membrane of target cell

13. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1b, step 2 Cytoplasm Nonsteroid hormone (first messenger) Enzyme Receptor protein Plasma membrane of target cell

14. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1b, step 3 Cytoplasm Nonsteroid hormone (first messenger) Enzyme Receptor protein Second messenger Plasma membrane of target cell ATP cAMP

15. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 9.1b, step 4 Cytoplasm Nonsteroid hormone (first messenger) Enzyme Receptor protein Second messenger Effect on cellular function, such as glycogen breakdown Plasma membrane of target cell ATP cAMP

16. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Examples of...  Steroid Hormones (Direct Gene Activation)  Testosterone  Estrogen  Progesterone  Adrenal cortex hormones  Glucocorticoids & Mineralcorticoids

17. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Examples of...  Second – Messenger Molecules  cAMP  cGMP  Calcium ions  Protein & Peptide Hormones (Second-Messenger System)  Melatonin  ADH (antidiuretic hormone)  Insulin