1 / 22

Organisms Use Feedback Mechanisms

College Board: 2.C – Organisms Use Feedback Mechanisms to Regulate Growth and Reproduction, and to Maintain Homeostasis. Organisms Use Feedback Mechanisms.

borka
Télécharger la présentation

Organisms Use Feedback Mechanisms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. College Board: 2.C – Organisms Use Feedback Mechanisms to Regulate Growth and Reproduction, and to Maintain Homeostasis

  2. Organisms Use Feedback Mechanisms • Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating physiological processes, returning the changing condition back to its target set point. • Operons in gene regulation • Temperature regulation in animals • Plant responses to water limitations

  3. Organisms Use Feedback Mechanisms • Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved farther away from the initial set-point. Amplification occurs when the stimulus is further activated which, in turn, initiates an additional response that produces system change • Lactation in mammals • Onset of labor • Ripening of fruit

  4. Organisms Use Feedback Mechanisms • Alteration in the mechanisms of feedback often results in deleterious consequences • Diabetes mellitus in response to decreased insulin • Dehydration in response to decreased antidiuretic hormone (ADH) • Grave’s disease (hyperthyroidism) • Blood clotting

  5. Homeostasis • Cells/organisms use energy to maintain homeostasis • Two mechanisms: • Negative feedback • Positive feedback

  6. Feedback • __________________= hypothalamus, detects a stimulus beyond the threshold (cold/hot) • ___________________= brain • ___________________=muscle, sweat gland

  7. TRH Examples of Negative Feedback Loops Anterior pituitary T3 T4

  8. Negative Feedback - _______________________ • Basic unit of genetic expression in _________________ • Sequence of genes that produces a series of _________________ that produce a final product • Advantages: • All enzymes are produced at the _______ _______ • Can be controlled at one site _________________

  9. Operons • 4 parts: • _______________________ gene – produces a controller protein • ____________________site – attachment for RNA polymerase • ______________________site – blocks/unblocks RNA polymerase • Structural genes – produces enzymes for a reaction Structural genes - enzymes Regulatory gene Promoter Gene 1 Gene 2 Gene 3 Operator DNA

  10. lacOperon • Normally ___ (bacteria normally use ______________) • Must be _________________ (‘turned on’) • Repressor protein produced by the regulatory gene blocks operator • Lactose ___________________________________of the repressor • Regulatory protein is removed from operator site • Operon becomes active (‘induced’)

  11. TrpOperon • Repressible – normally ____ must be turned ____ • If _______________________is present it attaches to regulatory protein • Regulatory protein + ___________________attaches to operator site blocking transcription

  12. Negative Feedback - Temperature Regulation • Receptors • Integrator • Effectors • Fever

  13. Negative Feedback - Plant Responses to Dehydration • ___, ________

  14. Positive Feedback • A stimulus causes ____________________ response to an activity that is already happening • Ex. ________________, _______________________ • Can be dangerous (fever)

  15. Positive Feedback - Ripening of Fruit • _____________________Gas stimulates production of enzymes • ‘One bad apple spoils the bunch’

  16. Alterations of Feedback – • Diabetes mellitus in response to decreased insulin • Too much glucose excreted (mellitus – ‘sweet’) • Role of insulin __________________________ • Dehydration in response to decreased antidiuretic hormone (ADH) (vasopressin) • Neuro-secretory • ____________ water absorption in collecting tubule of kidneys

  17. Regulation by ADH • ADH • Stored and secreted by the posterior pituitary • Concentrates nitrogenous wastes as urine • Urea with less _______________ • Diabetes insipidus

  18. Aquaporins

  19. Alterations of Feedback • Grave’s disease: • Autoimmune – antibodies attach to TSHR on cells of the thyroid gland causing the thyroid to overproduce thyroid hormones (T3 and T4) • Most common cause of ____________________ • Hereditary – mostly females • Goiter

  20. Alterations of Feedback • Blood clotting • Hemophilia – genes for clotting factors VIII and IX

  21. Integration and Coordination • Nervous system - brain, spinal cord, nerves, and sense organs • Integrates incoming information from receptors and sends impulses to muscles and glands (electrical) • Hypothalamus – neurohormonal • Endocrine system - glands that secrete hormones • Control metabolic functions (chemical) • Review: steroid and nonsteroid hormones

More Related