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  2. Biochemical switches in the cell cycle - Wikipedia

    en.wikipedia.org/wiki/Biochemical_switches_in...

    The interaction between the two types of loops is evident in mitosis. While positive feedback initiates mitosis, a negative feedback loop promotes the inactivation of the cyclin-dependent kinases by the anaphase-promoting complex. This example clearly shows the combined effects that positive and negative feedback loops have on cell-cycle ...

  3. Membrane potential - Wikipedia

    en.wikipedia.org/wiki/Membrane_potential

    The system as a whole is electro-neutral. The uncompensated positive charges outside the cell, and the uncompensated negative charges inside the cell, physically line up on the membrane surface and attract each other across the lipid bilayer. Thus, the membrane potential is physically located only in the immediate vicinity of the membrane.

  4. Hodgkin cycle - Wikipedia

    en.wikipedia.org/wiki/Hodgkin_Cycle

    The Hodgkin cycle represents a positive feedback loop in which an initial membrane depolarization leads to uncontrolled deflection of the membrane potential to near V Na. The initial depolarization must reach or surpass a certain threshold in order to activate voltage-gated Na + channels .

  5. Voltage clamp - Wikipedia

    en.wikipedia.org/wiki/Voltage_clamp

    This is a "patch-clamp electrode" (as distinct from a "sharp electrode" used to impale cells). This electrode is pressed against a cell membrane and suction is applied to pull the cell's membrane inside the electrode tip. The suction causes the cell to form a tight seal with the electrode (a "gigaohm seal", as the resistance is more than a ...

  6. IMViC - Wikipedia

    en.wikipedia.org/wiki/IMViC

    The IMViC tests are a group of individual tests used in microbiology lab testing to identify an organism in the coliform group. A coliform is a gram negative , aerobic, or facultative anaerobic rod, which produces gas from lactose within 48 hours.

  7. Epithelial polarity - Wikipedia

    en.wikipedia.org/wiki/Epithelial_polarity

    The first principle is positive feedback. In computer models, a molecule that can be either membrane-associated or cytoplasmic can polarize when its association with the membrane is subject to positive feedback: that membrane localization occurs most strongly where the molecule is already most highly concentrated.

  8. Depolarization - Wikipedia

    en.wikipedia.org/wiki/Depolarization

    This difference in charge is called the cell's membrane potential. In the process of depolarization, the negative internal charge of the cell temporarily becomes more positive (less negative). This shift from a negative to a more positive membrane potential occurs during several processes, including an action potential. During an action ...

  9. Sodium channel - Wikipedia

    en.wikipedia.org/wiki/Sodium_channel

    This is an example of a positive feedback loop. The ability of these channels to assume a closed-inactivated state causes the refractory period and is critical for the propagation of action potentials down an axon. Na + channels both open and close more quickly than K + channels, producing an influx of positive charge (Na +) toward the ...