Chapter 18:
Organisms use negative feedback mechanisms to maintain their internal environments by returning the changing condition back to its target set point, while positive feedback mechanisms amplify responses.
Alterations in feedback mechanisms can have deleterious effects, including diabetes and Graves' disease in humans and the inability of plants to tolerate water stress during drought.
a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating psyiological processes, returning the changing condition back to its target set point.
- operons in gene regulation
b. Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved further 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. Alterations 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
Multiple mechanisms regulate the timing and cooredination of molecular, phsiological and behavioral events that are necessary for an organism's development and survival. Cell differentiation results from the expression of genes for tissue-specific proteins, and the induction of transcription factors during development results in sequential gene expression. Cell differentiation also results from specific silencing of gene expression. For example, homeotic genes determine developmental patterns and sequences, and temperature and water availability determine seed germination in most plants. Genetic transplantation experiments support the link between gene expression, mutations and development.
a. Observable cell differentiation results from the expression of genes for tissue-specific proteins.
b. Induction of transcription factors during development results in sequential gene expression.
c. Embryonic induction in development results in the correct timing of events.
d. Temperature and the availability of water determine seed germination in most plants.
e. Genetic mutations can result in abnormal development.
f. Genetic transplantation experiments support the link between gene expression and normal development.
g. Genetic regulation by microRNAs plays an important role in the development of organisms and the control of cellular functions.
Physiological events in organisms can involve interactions between environmental stimuli and internal molecular signals.
The student can justify a claim made about the effect(s) on a biological system at the molecular, physiological or organismal level when a given scenario in which one or more components within a negative regulatory system is altered.
The student is able to evaluate data that show the effects of changes in concentrations of key molecules on negative feedback mechanisms.
The student is able to justify that positive feedback mechanisms amplify responses in organisms.
Alterations in feedback mechanisms can have deleterious effects, including diabetes and Graves' disease in humans and the inability of plants to tolerate water stress during drought.
a. Negative feedback mechanisms maintain dynamic homeostasis for a particular condition (variable) by regulating psyiological processes, returning the changing condition back to its target set point.
- operons in gene regulation
b. Positive feedback mechanisms amplify responses and processes in biological organisms. The variable initiating the response is moved further 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. Alterations 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
Multiple mechanisms regulate the timing and cooredination of molecular, phsiological and behavioral events that are necessary for an organism's development and survival. Cell differentiation results from the expression of genes for tissue-specific proteins, and the induction of transcription factors during development results in sequential gene expression. Cell differentiation also results from specific silencing of gene expression. For example, homeotic genes determine developmental patterns and sequences, and temperature and water availability determine seed germination in most plants. Genetic transplantation experiments support the link between gene expression, mutations and development.
a. Observable cell differentiation results from the expression of genes for tissue-specific proteins.
b. Induction of transcription factors during development results in sequential gene expression.
c. Embryonic induction in development results in the correct timing of events.
d. Temperature and the availability of water determine seed germination in most plants.
e. Genetic mutations can result in abnormal development.
f. Genetic transplantation experiments support the link between gene expression and normal development.
g. Genetic regulation by microRNAs plays an important role in the development of organisms and the control of cellular functions.
Physiological events in organisms can involve interactions between environmental stimuli and internal molecular signals.
The student can justify a claim made about the effect(s) on a biological system at the molecular, physiological or organismal level when a given scenario in which one or more components within a negative regulatory system is altered.
The student is able to evaluate data that show the effects of changes in concentrations of key molecules on negative feedback mechanisms.
The student is able to justify that positive feedback mechanisms amplify responses in organisms.