Theme: Feedback mechanisms regulate biological systems
Discuss theme, define feedback, negative feedback, positive feedback.
- Regulation of biological processes is crucial to the operation of living systems.
- Ex: Muscle cells require more energy during exercise, they increase their consumption of the sugar molecules that serve as fuel. When you rest, a different set of chemical reactions converts surplus sugar to storage molecules. Those chemical processes of the cell that either decompose or store sugar are accelerated (catalyzed) by proteins called enzymes. Each type of enzyme catalyzes a specific chemical reaction.
- -The key is the ability of many biological processes to self-regulate by a mechanism called feedback.
- -Feedback regulation: the output or product of a process regulates that very process
- -Negative feedback: the most common form of regulation in living systems, in whcih accumulation of an end product of a process slows that process
- Ex (neg feedback): the cell's breakdown of sugar generates chemical energy in the form of a substance called ATP. When the cell makes more ATP than it can use, the excess ATP "feeds back" and inhibits an enzyme neart the beginning of the pathway.
- -Positive feedback: an end product speeds up its own production.
- Ex (pos feedback): The clotting of your blood in response to injury. When a blood vessel is damaged, structures in the blood called platelets begin to aggregate at the site. Positive feedback occurs as chemicals released by the platelets attract more platelets. The platelet pileup then initiates a comples process that seals the wound with a clot.