C2.1 Chemical Signalling Flashcards
Local signalling (4)
cell-cell recognition
local regulators
paracrine (growth factors)
synaptic (neurotransmitter)
Long distance signalling
hormones
Define a ligand
specially shaped molecule that will bind to a specifically shaped larger molecule
Define receptors (2)
specifically shaped proteins that will bind to certain signal molecules
changes shape after binding ligand
Creating action potentials
generator potential - few sodium channels opened to create small depolarisation
many generator potentials come together to reach the threshold of an action potential
refractory period
Applications of quorom sensing (3)
medicine - blockicng receptors of bacteria
biomediation - breakdown pollutants from environment
food spoilage - autoinducers block receptors of bacteria which cause food spoilage
Categories of cell signalling (4)
paracrine signalling
autocrine signalling
endocrine signalling
signaling by direct contact
Gap Junctions as direct contact cell-cell communication
cells are in direct contact
protein channels connect 2 adjoining
Paracrine signalling
simultaneous response to more than one cell
Synaptic signalling (2)
nervous system
neurotransmitters diffuse from one nerve cell to stimulate the next
Intercellular signalling (2)
communication among cells
through signalling molecules
Examples of signalling molecules (4)
proteins, small peptides, amino acids
nucleotides
steroids, retinoids, fatty axis derivatives
nitric oxide, carbon monoxide
Hydrophilic signalling molecules (5)
proteins
amino acids
peptides
nucleotides
cannot pass through cell membrane
Hydrophobic signalling molecules (3)
steroids - hormones
gases
can enter cell membrane
Endocrine signalling (3)
signalling molecules (hormones) secreted by spceialised endocrine cells
carried through circulation to act on target cells at distant body sites
e.g lipid steroids (testosterone, estrogen)
Paracrine signalling (2)
moleucle (neurotransmitter) released by one cell acts on neighboring target cells
diverse group of hydrophillic molecules (dopamine, serotonin)
Signal transduction (3)
process where external signal becomes internal cellular response
cells receive signal + pass signal along using signal transduction
3 Stages of cell signalling (3)
reception - detection of signal molecule coming from outside of cell
transduction - convert signal to form that can bring about cellular response
response - cellular response to signal molecule
Features of reception in cell signalling (4)
complementary binding of signal molecule (ligand) to receptor
water soluble (hydrophillic) - binds to outside membrane
intracellular (hydrophobic) - bind to receptors inside the cell
ligand binds to receptor –> protein changes shape –> initiates transduction signal
Types of receptors (2)
plasma membrane receptor
intracellular receptor
3 most common types of membrane receptor proteins
G-protein coupled receptors
Receptor tyrosine
Describe G-protein cell receptor
cell surface transmembrane receptor
ligand binds to outside
passes through thr cell membrane 7 times
G-protein (complex) is inside the protein
Intracellular Receptors
signal molecule is hydrophobic
many are molecular switches
Types of switching on mechanisms in intracellular receptors (2)
phosphorylation -
GTP binding - GDP bound = inactive, GTP bound inactive
Examples of intracellular receptors
Testosterone
3 main classes of hormones (3)
Amino acid/amine hormones
peptide hormones
lipid based hormones
Features of amino acid hormones (3)
small molecules derived from amino acids tyrosine + tryptophan
water soluble - hydrophillic
bind to surface receptors
Features of peptide hormones (4)
polypeptide chains, small proteins, glycoproteins
include insulin + oxytocin
water soluble - hydrophillic
bind to surface receptors
Features of lipid-based hormones
derived from cholesterol
insoluble in water - hydrophobic
require carrier protein to attach to transport via blood
remain in circulation longer
Gonadotrophin releasing hormone (3)
causes pituitary gland to make + secrete hormones
men - these hormones cause testicles to make testosterone
women - cause ovaries to make estrogene + progesterone
Effects of estrogen
Features of estradiol (7)
mainly secreted by cells of ovarian follicles
regulates mesntrual cycle + reproduction
regulates bone density
regulates brain function
regulates cholesterol mobilisation
develops breast tissue + sexual organ
controls inflammation
Genomic Estrogen-mediated signalling
migration of estrogen-receptor complexes to the cell nucleus
direct interaction
