Transcript Communication & cell signalling

Communication & cell signalling
 Explain the term ‘cell signalling’
 Explain the role for membrane-bound receptors as
sites where hormones & drugs can bind
Cell Signalling
Cells communicate with each
other through signals
Inside the cell between
components
Outside the cell between cells
Different molecules send
different signals
To detect signals, cells must
have sensors-receptors (often
proteins)
Why do cells need to be able to communicate with each other and inside a
cell? Give a specific example for each.
4 points
 Single celled organisms-detect & move towards nutrients for survival
 Multicellular organisms-coordination between cells for:
o Growth
o Development
o Movement
o Excretion
 Detect internal & external signals
 Respond to signals and carrying out function/process
 Receptors detect the signals
Hormone Receptors
 Hormones=chemical messengers
transported in the blood
 Cell communication is often
mediated by a hormone
 Target cells-Any cell with a
receptor for a hormone
 Hormone & receptor on target
cell bind due to their
complementary shapes
(JIGSAW!)
 Binding causes the target cell to
respond in a certain way
Insulin
Where is insulin released from?
 Beta cells in islets of Langerhans in
the pancreas
Why is it released?
 In response to high glucose levels
What do you think happens when the
hormone binds to the receptor?
 Internal cell response triggered
More glucose channels become
present in the membrane
Cell takes up more glucose
Reduces blood glucose levels
Medicinal Drugs: Interfering with Receptors
Beta Blockers- Block receptors & prevent the heart muscle from increasing
the heart rate
Some drugs mimic natural neurotransmitters e.g. in Schizophrenia
Hijacking receptors:
 Viruses enter cells by binding with receptors on cells PM e.g. HIV
can enter cells of the immune system (T lymphocytes)
 Due to shape which fits into the receptor
 Prevents cells from doing its job/may destroy cell
How does Botox work?
 Uses a toxin from the bacterium Clostridium Botulinum
 Toxin binds with receptors on muscle fibres
 Prevents them working
 Causes paralysis
 If done in the face, reduces wrinkling of skin