Communication & Cell Signalling

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  • Created by: EnyaS
  • Created on: 01-10-15 16:41

Sensitivity and Responses

Living organisms can sense what is present in environment & respond appropriately to changes


Detect nutrient molecules in surrounding water, move towards them & take them in.                        If they are unable to do this, they cannot survive


Survive by each cell playing a part

  • Cells detect internal & external signals to carry out processes (e.g. growth, movement)
  • Must be able to carry out functions in response = extremely complex

                                                                                                                                                                    To detect signals, cells have receptors on their surface to recieve them (often proteins / modified proteins)

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Hormone Receptors

In multicellular organisms, communication between cells is often mediated by hormones.

Hormones = Chemical messengers produced in certain tissues and then released into the organism.                                                                                                                                       Any cell with a receptor for the hormone = target cell

The insulin receptor

  • Insulin released from beta-cells in the pancreas, in response to increased blood sugar levels
  • Insulin = Protein molecule that attatches to receptors on cell surface membrane
  • Triggers internal response (more glucose channels present in membrane)
  • Allows cell to take up more glucose from blood = reducing blood sugar levels

Medicinal drugs- interfering with receptors

  • Medicinal drugs have been developed = complimentary to receptor molecule
  • They are intended to block receptors. Beta-blockers used to prevent heart muscle from increasing heart rate
  • Some drugs mimic natural neurotransmitter that can't be produced (Schizophrenia)
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Hormone Receptors (continued)

Hijacking receptors

  • Viruses enter cells by binding with receptors
  • HIV infects humans as it can enter cells of immune system. It has a shape which fits a receptor on the cell surface
  • Once HIV enters, after a period of inactivity it may reproduce inside the cell and eventually destroy it
  • Poisons also bind with receptors
  • Toxin extracted from bacterium Clostridium botulinum binds with receptors on muscle fibres & prevents them from working properly = paralysis
  • Toxin = lethal, but is used in small amounts in BOTOX to paralyse muscles in the face, reducing wrinkling of the skin
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Cell Signalling

Cells communicate with one another by signals. Many molecules act as signals- some signal during processes taking place inside cells; others signal from one cell to another.                          Cytokines are an example of cell signals.

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