Molecular Basis of Health, Disease and Therapeutics Flashcards
What is the function of the plasma membrane?
Forms a barrier between internal and external environments of the cell
Describe the structure of the plasma membrane
- Phospholipid bilayer
- Hydrophilic heads
- Hydrophobic tails
- Hydrophobic core forms the barrier and prevents molecules from passing freely from external environment into the cell
What is a ligand?
A chemical signal that binds to another molecule
What happens when a ligand binds to its specific receptor?
- Receptor is activated
- Conformational change occurs
- Signal transduction
What are the 3 basic steps in a signalling pathway?
- Ligand-receptor binding
- Signal transduction
- Signal response
What type of protein are receptors usually?
Trans-membrane proteins
What are the 3 classes of membrane receptor?
- G-protein coupled receptor (GPCR)
- Enzyme linked receptor
- Ion channel receptor
Which group of membrane receptor are the largest and most diverse group?
G-protein coupled receptors (GPCRs)
What happens when a ligand binds to a GPCR?
- G protein coupled receptor activated
- Interacts with G proteins (GTP)
- Activated G proteins activate cell membrane proteins
What is cAMP?
Cyclic AMP - a 2nd messenger
How do enzyme coupled receptors work?
- Enzyme coupled receptors have intrinsic enzymatic activity
- Receptor Tyrosine Kinase (RTK) = largest family
- Tyrosine kinase adds phosphate to tyrosine
- RTKs typically bind proteins at low concentrations
What do receptor tyrosine kinases (RTK) play a role in?
Regulating growth, differentiation and survival
How do ion channels work?
- Ion channels convert chemical messages into electrical messages
- Ligand gated/voltage gated
- Important in neuronal and muscular action potentials
What does lidocaine block?
Voltage-gated Na+ channels
What are the 2 functions of signal transduction?
- To amplify the signal
2. Deliver the signal to effector proteins
What does cell communication ultimately lead to (usually)?
- Regulation of cellular responses
- e.g. many signalling pathways regulate the proteins translation by turning genes on or off
What are transcription factors?
Proteins that bind to DNA to regulate gene transcription
What is a common feature of ALL diseases?
All diseases have a molecular basis and may involve at least one breakdown in cellular communication
What do drugs often target?
Disrupted cell communication networks for therapeutic benefit
What are some of the ways in which cellular communication can fail?
- Loss of the signal
- Failure to respond to the signal
- Failure of signal to reach target cell
- Overexpression of signal
What type of breakdown in cellular communication occurs in Type I diabetes?
Loss of signal - beta cells are destroyed, can’t to produce insulin (the signal)
How can patients with Type I diabetes be treated?
With insulin injections
Not a cure, but can help mediate condition
What type of breakdown in cellular communication occurs in Type II diabetes?
- Failure to respond to the signal
- Insulin is produced but cells that usually respond to insulin lose their sensitivity and can no longer respond to the signal
What is the treatment recommended for type II diabetes?
Exercise and diet to regulate blood glucose levels
