Stas - signalling and what have you Flashcards
What are the types of chemical transport
Diffusion
Osmosis
Facilitated transport
Active transport
Give some types of chemical receptors and their response times
> Channel linked receptor (milliseconds)
G-protein coupled receptor (Seconds)
Kinase-linked receptor (Minutes)
Steroid receptor (hours)
Which receptor is
a) Ionotropic
b) Metabotropic
Ionotropic = Channel linked receptor (e.g. nicotinic receptor)
Metabotropic = G-protein coupled receptor
(eg muscarinic receptor)
What happens inside the cell after activation of a kinase-linked receptor before a cellular response happens
e.g. Insulin
Protein phosphorylation
What are the differences between ionotropic and metabotropic receptors?
Ionotropic receptors are molecules that can open or close to allow smaller particles such as ions to flow in and out of cells (lingand-gated transmembrane ion channels)
Metabotropic receptors are linked to a G-protein/enzyme, which is activated upon ligand binding and activates a secondary messenger such as an ion channel
Glutamate receptors and tyrpsine kinase receptors are metabotropic receptors
Give an example of direct cell to cell contact
adhesion molecules
Give an example of secreted ligands
- netrins
- neurotransmitters
- trophic factors etc.
What are the 2 main types of synaptic transmission
Electrical and Chemical
Give an example of an excitatory (spiny) and inhibitory (non spiny) transmitter
Excitatory = glutamate/aspartate
Inhibitory = GABA/glycine
What types of metabotropic receptors are INSIDE a cell
receptors for steroids and vitamins e.t.c
The _______ surrounding axons is critical to the propagation of action potentials. It essentially serves to maintain conductivity; without it, action potentials would travel much more slowly
Myelin sheith
What is the ligand for the NMDA receptor and what is it’s function?
Glutamate
Controlls synaptic plasticity and memory
The NMDAR is a specific type of ______ glutamate receptor
The NMDAR is a specific type of ionotropic glutamate receptor
The NMDA receptor forms a ______mer between two Glu__ and two Glu__ subunits
The NMDA receptor forms a heterotetramer between two GluN1 and two GluN2 subunits wo GluN2 subunits
NMDA receptor:
The extracellular domain contains two globular structures: a _____ domain and a _____ domain. NR1 subunits bind the co-agonist ____ and NR2 subunits bind the neurotransmitter ______.
The extracellular domain contains two globular structures: a modulatory domain and a ligand-binding domain. NR1 subunits bind the co-agonist glycine and NR2 subunits bind the neurotransmitter glutamate.
NMDA receptor:
Each subunit has an extensive cytoplasmic domain, which contain residues that can be directly modified by a series of protein ____ses and protein _____ses,
Each subunit has an extensive cytoplasmic domain, which contain residues that can be directly modified by a series of protein kinases and protein phosphatases,
____ not only blocks the NMDA channel in a voltage-dependent manner but also potentiates NMDA-induced responses at positive membrane potentials.
Mg2+ not only blocks the NMDA channel in a voltage-dependent manner but also potentiates NMDA-induced responses at positive membrane potentials.
Give some biological functions mediated by G-protein linked receptors
taste, smell, vision… via neurotransmission, cell growth and differentiation, reorganisation of cytoskeleton, intracellular transport and exo/endocytosis
What are the 2 types of G-proteins?
Heteritrimeric and
small g proteins
Give some features of G-proteins
e.g. signal amplification
> slower than ionotropic
offer great environment for regulation
long-lasting with regulated clock option
evolutionary old and >highly conserved
What are small G proteins and their use
Superfamily of “switch” proteins, which are essential regulators of signal transduction leading to organization of the cytoskeleton and cellular traffic.
e.g.
>Ras cell proliferation and differentiation
>regulation of nucleocytoplasmic transport of RNA and proteins during the G1, S, and G2 phases of the cell cycle and microtubule organization during the M phase
What are the components of the EGF transduction pathway
>Small G protein (EGF receptor and Phosphorylated tyrosine kinase domaine >Grb-2 adapter protein >Sos >Ras >GTPase activation protein
What are aniston cells?
hyper specific neurones responsible for memory.
Formed by potentiation of existing synapses and formation of new ones
What is long term potentiation?
a functional alteration in synaptic transmission, which results in a persistent upregulation of synaptic efficacy
Long term potentiation is:
•Rapidly induced, l_____, c____, a____, i____, a_____, c_______
Rapidly induced, long lasting, cooperative, additive, input specific, associative, competitive
What does the TAGS hypothesis seek to explain?
how neurosignalling at a particular synapse creates a target for subsequent PRP trafficking essential for sustained ovelapping LTP and LTD.
It has been established that they form as a result of high or low frequency stimulation, interact with incoming PRPs, and have a limited lifespan
What are plasticity products?
mRNA genetic artifacts and protein products triggered by transcription factors, leading to long-lasting long term potentiation (L-LTP) and sustained alterations in synaptic strength
What are the two types of long term potentiation and what do they mean?
S-LTP (short-lasting)
and L-LTP (long-lasting)
In S-LTP the stimulus is strong enough to induce long-term potentiation but too weak to trigger intracellular events necessary to sustain synaptic changes. L-LTP is much less transient than S-LTP and involves the generation of new proteins through translation and transcription
What is the genomic signaling hypothesis for induction of L-LTP
- A stimulus is strong enough to induce L-LTP is delivered.
- A signaling cascade begins, leading to phosphorylation of transcription factors.
- mRNA is produced leading to subsequent translation of new proteins to sustain synaptic changes.
What are the 9 sensory modules?
Sight, hearing, olfaction (smell), gustation (taste), vestibular sense of equilibrium, touch, pain, proprioception (sense of body position), temperature
What are the somatic sensory modules?
pain, proprioception (sense of body position), temperature
What are the features of rods, what do they contain and what vision are they responsible for?
Numerous (120mill), Sensitive, No colour
They are responsible for our dark-adapted, or scotopic, vision. Motion sensors. Contain rhodopsin
What are the features of cones, what do they contain and what vision are they responsible for?
= 6-7 mill, colour sensitivity, concentrated in the macula
“red” cones (64%), “green” cones (32%), and “blue” cones (2%)
Rhodopsins belong to the ______ receptor family and are extremely sensitive to ___, enabling vision in ____ conditions
Rhodopsins belong to the G-protein-coupled receptor family and are extremely sensitive to light, enabling vision in low-light conditions
Rhodopsin:
Exposed to light, the pigment immediately ______, and it takes about __ minutes to regenerate fully in human
Exposed to light, the pigment immediately photobleaches, and it takes about 45 minutes to regenerate fully in humans
Rhodopsin consists of the protein moiety ___ and a reversibly covalently bound cofactor, ____
Rhodopsin consists of the protein moiety opsin and a reversibly covalently bound cofactor, retinal
opsin binds _____
binds retinal (a photoreactive chromophore)
One of the most important differences between cones and rods is in the ______ sequence of the ____ component of the rhodopsin molecule
One of the most important differences between cones and rods is in the amino acid sequence of the opsin component of the rhodopsin molecule
Why do the cones in the three classes of vertebrate differ in their absorbtion spectra?
the amino acid sequence of their opsin molecules (opsin is the protein component of rhodopsin, the visual pigment that actually absorbs photons) differs
When the photoreceptors in the retina are not receiving light, they _______
depolarize
What reduces the incidence of spontaneous depolarization in retinal cells
Because the photoreceptors actually prevent the bipolar cells from depolarizing when they’re receiving no light
What are the degradation products of rhodopsin after receiving light energy?
(Remember the red bubblegum pneumonic)
Rhodopsin Bathorhodopsin Lumirhodopsin Metrahodopsin 1 Metrahodopsin2 Scotopsin
What is the pathway of odorants before reaching the olfactory epithelium?
Septum -> Vomeronasal organ -> Nasal cavity -> Olfactory epithelium
What is the pathway of odorants after reaching the olfactory epithelium before reaching the olfactory bulb?
Mucus layer -> Cilia of olfactory cells -> Olfactory receptor cell -> Basal cell -> Cribriform plate -> Olfactory nerve
The ends of the axons cluster in spherical structures known as ____ such that each glomerulus receives input primarily from olfactory receptor neurons that express the same olfactory receptor
glomeruli
What is the first level of synaptic processing?
The glomeruli layer of the olfactory bulb
How does binding of an odorant particle cause depolarisation?
> activates a G protein, which then activates adenylate cyclase, leading to cAMP production
. cAMP then binds and opens Cyclic nucleotide-gated ion channel
This opening allows for an influx of both Na+ and Ca2+ ions into the cell, thus depolarizing it
. The Ca2+ in turn activates chloride channels, causing efflux of Cl-, which results in a further depolarization of the cell.
What is the brain structure responsible for the perception of taste?
The primary gustatory cortex
What are the 2 structures of the primary gustatory cortex?
anterior insula on the insular lobe
frontal operculum on the frontal lobe
What is the mechanism of transduction of saltiness?
Na+ passes through Amiloride-sensitive sodium cation channel
What is the mechanism of transduction of sourness?
H+ passes through Amiloride-sensitive sodium cation channel
What is the mechanism of transduction of sweetness?
Sucrose passes through T1R2/T1R3 G-protein coupled receptor
What is the mechanism of transduction of bitterness?
T2R or TRPM channel
What is the mechanism of transduction of umami taste?
TRPM and T1R1/T1R3 channel coupled to G protein
