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  2. Cell polarity - Wikipedia

    en.wikipedia.org/wiki/Cell_polarity

    Epithelial cells also exhibit planar cell polarity, in which specialized structures are orientated within the plane of the epithelial sheet. Some examples of planar cell polarity include the scales of fish being oriented in the same direction and similarly the feathers of birds, the fur of mammals, and the cuticular projections (sensory hairs ...

  3. Positive feedback - Wikipedia

    en.wikipedia.org/wiki/Positive_feedback

    Positive feedback occurs when a gene activates itself directly or indirectly via a double negative feedback loop. Genetic engineers have constructed and tested simple positive feedback networks in bacteria to demonstrate the concept of bistability. [28] A classic example of positive feedback is the lac operon in E. coli. Positive feedback plays ...

  4. Climate change feedbacks - Wikipedia

    en.wikipedia.org/wiki/Climate_change_feedbacks

    The Planck response is the additional thermal radiation objects emit as they get warmer. Whether Planck response is a climate change feedback depends on the context. In climate science the Planck response can be treated as an intrinsic part of warming that is separate from radiative feedbacks and carbon cycle feedbacks.

  5. Biochemical switches in the cell cycle - Wikipedia

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

    Positive feedback loops play a role by switching cells from low to high Cdk-activity. 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.

  6. List of unsolved problems in biology - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    Morphology problem. How are neural tissues formed in specific ways in different species? The formation of neural tissues in a certain way is necessary for the formation of certain goal-directed behavior for certain species.

  7. Earth's energy budget - Wikipedia

    en.wikipedia.org/wiki/Earth's_energy_budget

    A slower positive feedback is the ice-albedo feedback. For example, the loss of Arctic ice due to rising temperatures makes the region less reflective, leading to greater absorption of energy and even faster ice melt rates, thus positive influence on ΔE S. [30] Collectively, feedbacks tend to amplify global warming or cooling. [31]: 94

  8. Temporal feedback - Wikipedia

    en.wikipedia.org/wiki/Temporal_feedback

    Within molecular and cell biology, temporal feedback, also referred to as interlinked or interlocked feedback, is a biological regulatory motif in which fast and slow positive feedback loops are interlinked to create "all or none" switches. This interlinking produces separate, adjustable activation and de-activation times.

  9. Feedback - Wikipedia

    en.wikipedia.org/wiki/Feedback

    Positive feedback: If the signal feedback from output is in phase with the input signal, the feedback is called positive feedback. Negative feedback: If the signal feedback is out of phase by 180° with respect to the input signal, the feedback is called negative feedback. As an example of negative feedback, the diagram might represent a cruise ...