OCR Biology - Cell Signalling

• Can be categorised based on the distance over which the signalling occurs

Endocrine Signalling

• large distances
• ofen where the signalling molecule is transported in the circulatory system 

Paracrine Signalling

• ccurs between cells which are close together
• sometimes directly
• sometimes via extracellular fluid

Autocrine Signalling

• is where the cell stimulates a response within itself 
• by releasing signals for its own receptors 

• Invade cells by binding to Cell Receptor Sites that are normally used in cell signalling
• Poisons binds to the Cell Receptors
  • Prevents the targeted cells from working properly

• Work because they are complementary to certain Cell Receptors Sites
• Some drugs block these Receptors so that the natural signalling molecules can't stimulate a response
• Others are designed to mimic natural signalling molecules that the body can't produce

• Used in cell signalling molecules in multicellular organisms
• Produced in a cell
  • Sometimes in response to environmental changes
• Hormones are released and bind to Receptor Sites on a Target Cell and starts a response

Hormone Mediated Cell Signalling Pathway Example

• Is in the use of Insulin to lower blood glucose levels
• Beta-Cells in the pancreas release the hormone insulin in to the blood in response to high glucose levels
  • Binds to the cells such as mucle and liver cells
  • Causes them to take up more glucose

• Cells detect signals with Cell Receptors on their plasma membranes
  • which are usually Glycoproteins or Glycolipids
• The signalling molecule binds to the Receptor because its shape is complementary
• This stimulates a response

• Cells need to interact with their environment and other cells around them
• Single cellular organisms need to detect nutrients in their environment
• Cells in multicellular organisms are involved in a complex system of communication with each other