2. Biological systems utilize free energy and molecular building blocks to grow, to reproduce and to maintain dynamic homeostasis. A.Growth Reproduction and maintenance of the organization of living systems require free energy and matter. B.Growth, reproduction and dynamic homeostasis require that cells create and maintain internal environments that are different from their external environments. C.Organisms use feedback mechanisms to regulate growth and reproduction, and to maintain dynamic homeostasis. D.Growth and dynamic homeostasis of a biological system are influenced by changes in the systems environment. E.Many biological processes involved in growth, reproduction and dynamic homeostasis include temporal regulation and coordination.
2.C. Organisms use feedback mechanisms to regulate growth and reproduction, and to maintain dynamic homeostasis. 1.Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. 2.Organisms respond to changes in their external environments.
2.C.1. Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. a.Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulation physiological processes, returning the changing condition back to its target set point. b.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. c.Alteration in the mechanisms of feedback often results in deleterious consequences.
2.C.1.a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulation physiological processes, returning the changing condition back to its target set point. Operons – trp Operon – lac Operon Temperature Regulation Plant Response to Water Limitations
trp Operon On by default – repressible
lac Operon Off by default - inducible
Lac Operon (continued) This operon is further enhanced when glucose is in short supply.
2.C.1.a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulation physiological processes, returning the changing condition back to its target set point. Operons – trp Operon – lac Operon Temperature Regulation Plant Response to Water Limitations
Temperature Regulation in Mammals
2.C.1.a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulation physiological processes, returning the changing condition back to its target set point. Operons – trp Operon – lac Operon Temperature Regulation Plant Response to Water Limitations
2.C.1. Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. a.Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulation physiological processes, returning the changing condition back to its target set point. b.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. c.Alteration in the mechanisms of feedback often results in deleterious consequences.
2.C.1.b. 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 in childbirth Ripening of fruit
Onset of Labor in Childbirth
2.C.1. Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. a.Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulation physiological processes, returning the changing condition back to its target set point. b.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. c.Alteration in the mechanisms of feedback often results in deleterious consequences.
2.C.1.c. Alteration in the mechanisms of feedback often results in deleterious consequences. Diabetes Mellitus – Type 1 – lack of insulin production – Type 2 – decreased response to insulin
2.C.1.c. Alteration in the mechanisms of feedback often results in deleterious consequences. Graves Disease – Antibodies bind to TSH receptors – Overproduction of T 3 and T 4 – Exophthalmos, Hyperactivity, Nervousness, Irritibality, Insomnia
2.C. Organisms use feedback mechanisms to regulate growth and reproduction, and to maintain dynamic homeostasis. 1.Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes. 2.Organisms respond to changes in their external environments.
2.C.2. Organisms respond to changes in their external environments. a.Photoperiodism and phototropism in plants b.Hibernation and migration in animals c.Taxis and kinesis in animals d.Chemotaxis in bacteria, sexual reproduction in fungi e.Nocturnal and diurnal activity: circadian rhythms f.Shivering and sweating in humans
2.C.2.a. Photoperiodism
Organisms respond to changes in their external environments. a.Photoperiodism and phototropism in plants b.Hibernation and migration in animals c.Taxis and kinesis in animals d.Chemotaxis in bacteria, sexual reproduction in fungi e.Nocturnal and diurnal activity: circadian rhythms f.Shivering and sweating in humans