Feedback

Feedback Mechanisms in Cell Communication

Overview of Feedback Mechanisms

• Feedback mechanisms are crucial controls in biological systems and are vital to maintaining homeostasis.
• They function to either amplify (positive feedback) or minimise (negative feedback) the effects of certain processes.

Positive Feedback

• Positive feedback amplifies or enhances the output of a system.
• It promotes change and drives processes to completion. For example, when a cell is damaged, more immune cells are recruited to the site to accelerate the healing process.
• Positive feedback can also create a self-perpetuating cycle, where the output enhances the original stimulus.

Negative Feedback

• Negative feedback reduces or suppresses the output of a system.
• It maintains an organism’s internal environment at a constant, optimal level by counteracting any changes that stray from the ideal. For example, when glucose levels rise in the blood, insulin is released to decrease the glucose level.
• Negative feedback is crucial for moderating metabolic reactions and maintaining homeostasis.

Role of Feedback in Cell Cycle

• Feedback mechanisms also play a crucial role in the cell cycle.
• For instance, some proteins monitor and control the progress of the cell cycle, providing a form of negative feedback to ensure that cells do not divide prematurely.
• Additionally, regulation of proteins involved in the cell cycle can be influenced by signals from other cells, integrating cell cycle control with other cellular functions and environmental conditions.

Feedback in Signal Transduction

• Feedback loops are integral in signal transduction pathways. They can amplify the signal (positive feedback) or dampen it (negative feedback).
• For example, in enzyme-linked receptor signalling, the activation of a small number of enzymes can result in a large output of second messengers, an instance of positive feedback.
• Conversely, in G-protein-linked receptor signalling, the system can be shut down rapidly after the signal has been received, a feature of negative feedback.