Overview of cell signalling Flashcards
what is cell signalling?
Cell to cell communication
what are the steps of cell signalling?
- synthesis of signalling molecule
- release of signal molecule
- transport of signal molecule to target
- detection of signal (reception) by target cell
- responce by target cell
- some form of feedback- signal has been received
what are examples of chemical singalling molecules?
Steriod
Amino acid
Amine
gas
peptide
protein
what is the keu factor in a singalling molecules?
Whether it is lipid soluble or water soluble
what are the features of water soluble signalling molecules?
- can be stored in lipid vessicles within the singalling cell
- allow rapid release via exocytosis
- can travel in blood without a carrier
- cannot entre target cell
- message tranduced via cell surface receptor
what are the features of lipif soluble signalling molecules?
- cannot be stored in lipid vesicles with the signalling cell
- slow response because it must be made on demand
- travels in blood with a carrier protein, may be longer lasting
- can enter target cells by crossing their membrane
- acts on intracellular receptors often to directly regulate gene expression
what are the different types of cell signalling?
Juxtacrine
Autocrine
Paracrine
Endocrine
Neuronal
Neuroendocrine
what does juxtacrine signalling require?
Direct cell to cell contact
what junctions mediate juxtacrine signalling?
Gap junctions
what are gap junctions comprised of?
Proteins called connexins
what do gap junctions transport?
- Allows ions and small molecules to move between cells
- Bi-directional transport
- provide electrical and chemical coupling between cells
- allow rapid communication between groups of cells
How does juxtacrine signalling work?
- juxtacrine signalling can involve receptors
- but the signalling molecule is not released
- can use the notch pathway
what is the notch pathway?
Ligand on signal sending molecule
Attaches to notch
This releases a signal
Activating the pathway
Can deliver more complex information than gap junctions
-Specificity achieved by receptor expression and direct contact
what are the features of autocrine signalling?
-Signalling between nearby cells of the same type
- requires the release and detection of signal molecule
- can coordinate activity between a group of similar cells
- specificity achieved by selective receptor expression and rapid degradation of signal molecule
what are the features of paracrine signalling?
-local signalling between different cell types
- requires the release and detection of signal molecules
- specificity achieved by selective receptor expression and rapid degradation of signal molecule
what are the features of endocrine signalling?
- often involves signalling between distant cells
- chemical signals called hormones carried in the blood
- hormones produced from discrete endocrine glands, endocrine tissues are isolated cells
- hormones are of multiple chemical types (steroids, modified amino acids, peptides)
- specificity achieved by seletive receptor expression
what are the features of neuronal signalling?
- signalling molecules (neurotransmitter) released from neurons at specialized highly localized synaptic sites.
- Neurotransmitters are of multiple chemical types (amino acids, amines, peptides)
- cause rapid and often short-lasting effects
- specificity achieved by precise contacts and rapid removal of neurotransmitter to prevent diffusion
what are the features of neuroendocrine signalling?
- neurotransmitters released from neurons into the blood
- important in the regulation of the endocrine system
- hypothalamic neurons project to the posterior pituitary to control hormone (ADH and oxytocin) release into the systemic circulation
- other hypothalamic neurons control hormone release from the anterior pituitayr
-Neuroendocrine cells in the adrenal medulla release catecholamines into the blood in response to stress
what signals cell growth?
Growth factors
what signals division in a cell?
Mitogens
what are the signals that could be between cells?
grow
divide
die
differentiate
become active
what are the different active signals a cell could recieve?
- contract
- move
- fire an action potential
- release a signal of its own
- make more of something
- break down more of something
how can receptor activity change cellular activity?
Receptor activity by a signal may change the amount or the activity of specific proteins which then mediate an effect
what are some of the cellular changes that can occur within a cell?
- alter gene expression for a specific protein
- alter the activity of specific proteins
- alter signaling often does both
