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From cells to organisms > Colm Cunningham - cell to cell communication > Flashcards

Colm Cunningham - cell to cell communication Flashcards

1
Q

what is quorum sensing?

A

Quorum sensing is a phenomenon in which microbial cells interact and communicate with each other by secreting some chemical molecules to which other cells. remember the bobtail squid and the vibrio fisheri
singling molecule

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2
Q

AUTOINDUCER used for vibrio fisherciheri

A

Acyl-Homoserine Lactone

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3
Q

cell-cell signalling

A

-Molecule released by cell
– Both that cell and other local cells can respond
– Via receptor-mediated signalling
– Concluding with activation of transcription factors
– Changes in gene expression, change in cell
behaviour

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4
Q

Juxtracrine signalling is an example of….

A

contact dependent signalling

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5
Q

outline gap- junctions

A

the pacemaker cells in the heart or the cardiac myosites must contract together via the passage of ions. Gap junctions or connections in cytoplasm allow for this.

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6
Q

Intercalated discs are points

A

are which 2 cardiomyocytes are joined part and they contain two structures important in cardiac muscle contraction: gap junctions and
desmosomes.

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7
Q

The function is called

A

electric coupling

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8
Q

where dos the signal for the pacematers beginning where?

A

begins with the pacemaker cells IN THE SINO-ATRIAL NODE

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9
Q

what drives the pumping of the pacemaker cells?

A

Sodium channels, then calcium channels, THEN potassium channels – so we depolarise, then further, then with K we reploarise. All are voltage gated so open AND close according to the voltage so it constantly cycles (never at resting potential). The myocyte (cardiac muscle) is quite different –
as depolarisation starts and calcium wants to come in and potassium wants to move out, they work sort of in opposition the membrane potential plateaus a little
above neutral.

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10
Q

Plasmodesmata:

A

ER extension – desmotubule
Cytoplasmic sleeve (around tubule)

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11
Q

What molecules move between cells through the plasmodesmata?

A

Proteins, mRNAs and gene silencing signals use these channels for movement

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12
Q

plasmodesmata

A

interconnections convey molecules ‘away from’ the
veins.

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13
Q

notch signalling can do what

A

alter metabolism
alter cytoskeleton
alter gene expression

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14
Q

Endocrine signalling

A

the signaling molecules (hormones) are secreted by specialized endocrine cells and carried through the circulation to act on target cells at distant body sites

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15
Q

Paracrine signalling

A

eg the synapse

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16
Q

Autocrine signalling example

A

cell to itself eg T cell cytokine interleukin-2 (IL-2)

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17
Q

give 2 examples of paracrine signalling

A

Cytokines released by immune
cells act on multiple populations
Morphogens released to drive
patterning during development
Neurotransmitters released
locally act on multiple target

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18
Q

give an example of a morphogen

A

WNT protiens form as morphogens causing a secretion gradient

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19
Q

what are the steps of WNT signalling pathway

A

The signalling
molecule Wnt binds
to the frizzled
receptor.
β-catenin
plays a
central role
No transcription
2. In the case of
stimulation of the
canonical pathway
(there are other
possible outcomes),
ß-catenin is
stabilised in the
cytoplasm
3. is transported to
the nucleus
4. where it binds to
the transcription
factor Tcf and turns
on gene expression.

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20
Q

Neuromuscular junction – acetylcholine (Ach)

A

na+ inflow, k+ outflow
depolarisation of end plate

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21
Q

Gorge Palade

A

leucine is labelled radioactively and thus is built into the cell’s protein pulse chance phase also identified

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22
Q

types of chaperones

A

Calnexin & calreticulin – chaperones that retain
incompletely folded proteins in the ER-THEY CAN’T LEAVE ER UNTIL FOLDING IS COMPLETE

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23
Q

what is a obliglucccharide

A

a saccharide polymer containing a small number (typically three to ten) of monosaccharides (simple sugars)

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24
Q

which amino acid is added in protein folding

A

asparagine

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25
how big are er transport vesicles
ER transport vesicles ~50 nm
26
where do they merge and what coat do they have?
cis-golgi network cop II coat
27
what does proinsulin mature into
insulin and c-peptide
28
what type of folding does preproinsulin undergo?
disulphide bonding
29
what cuts preproinsulin
endopeptidase
30
where does this cleavage occur?
in the secretory vesicles
31
synaptotagmins
were proposed to function as calcium sensors in the regulation of neurotransmitter release and hormone secretion
32
Zn2+
is essential for the correct processing, storage, secretion, and action of insulin condensation
33
name one type of vesicle
Dense core granules
34
name two types of neurons( point is that there are many)
granule cell, spindle shaped cell
35
what structures are important ofneurotransmitters
cell, axon, synapse
36
Neurotransmission is
is the conversion of an electrical signal to a chemical signal, that allows the signal to pass from one cell to the next
37
Otto Loewi - what did he do?
proves the existence of acetyl choline by using frog hearts in synapse vagus nerves connection is key to this experiment acetylcholine
38
types of neurotransmitter
Biogenic amines – dopamine, noradrenaline, serotonin Amino acid neurotransmitters – glutamate, GABA Other types – Acetylcholine, NO, D-serine, neuropeptides
39
Glutamate and GABA
Major Excitatory, inhibitory Neurotransmitters respectively
40
Catecholamine biosynthesis: dopamine and noradrenaline
form tyrosine to dopa to dopamine to noradrenaline
41
what enzymes are required for this synthesis
thyrosine hydroxylase, dopa decarboxylase,dopamine b-hydroxylase
42
where are amine transmitters located?
Amine neurotransmitters are synthesised enymatically in the cytosol and then packaged into vesicles in the synaptic terminal
43
what 2 key proteins on small synaptic vesicle
They are specialised in their expression of 2 key proteins - a vesicular neurotransmitter transporter - a vesicular ATPase, which pumps H+ into the lumen.
44
what does atp synthesis require
Vesicular ATPase: pumps H+ into vesicle against concentration gradient and therefore requires ATP hydrolysis, vesicular neurotransmitter transporter: transports NT into vesicle against concentration gradient
45
what are vmats and what are their inhibitors?
the vesicular monoamine transporter (VMAT) is a transport protein integrated into the membranes of synaptic vesicles of presynaptic neurons. It transports monoamine neurotransmitters – such as dopamine, serotonin, norepinephrine, epinephrine, and histamine – into the vesicles inhibitors= Tetrabenazine: treatment for hyperkinesia Reserpine: antipsychotic
46
what two signalling are calcium dependent?
paracrine, endocrine
47
during resting membrane potential what side is positive and which is negative?
extracellular side pos cytoplasmic side- negative
48
in these terms what is charge sepration?
Charge separation! The charge on each side is highly ‘regulated’ but it is not balanced
49
how does a synaptic channel open
ligand ie neurotransmitter causes channel to open
50
depolarisation does what?
Depolarisation does make the membrane potential LESS NEGATIVE, but must cross threshold to trigger AP: “all or none
51
action potential happens how?
1.ligand- gated na+ channels depolarise membrane 2.voltage gated na+ channels depolarize further.
52
endplate potential happens where?
when a neuron synapses on a muscle cell
53
axon potential
na+ into the cell, k+ out of the cell
54
what are their relative amounts
High extracellular Na+ (440mM vx 50) High intracellular K+ (400mM vs 20)
55
what is the difference between ca+ and na+
Na+ is the electrical trigger for depolarisation Ca2+ is the chemical signal for neurotransmitter release
56
what is the docking cycle ?
1.Docking of a subset of these at AZ 2.Priming (for Ca2+- dependent exocytosis 3. Ca2+ triggering of fusion pore opening) 4. Recycling
57
what is the difference between t and v snare
v snares are on the vesicle t snares are on the target membrane
58
what are the 3 types of snares?
synaptobrevin syntaxin-1 snap- 25
59
what forms the snare complexes?
munc 18
60
LCs are zinc-dependent endopeptidases, function
which specifically cleave neuronal SNARE
61
name two toxins and what they work on-
Botulinum toxin (ACh), Tetanus toxin (GABA)
62
what is Synaptotagmin
sensor of calcium/ receptor- removes complexin allowing the complex to open.
63
how can these highly used neurtoransmitters be recycled?
use of a clathrin coat kiss and run model- only partial emptying of the vesicle ultra falst endcytosis
64
AXON HILLOCK
Voltage-gated sodium channels (depolarisation) INITIATE ACTION POTENTIAL if crossing threshold Voltage-gated potassium channels - Repolarisation
65
AXON
- Propagation of action potential Voltage-gated potassium channels and sodium channels - Repolarisation, prevention of back propagation
66
dendrites
collect electrical signal
67
ionotropic
ligand gated ion channels direct neurotransmitters binding opening
68
metrotropic receptors
g coupled receptors indirect activation through the use of g-protein. slower mode of action.
69
receptor classes?
nicotinic , Muscarinic
70
nicotinic
activated by nicotine ionotropic
71
Muscarinic
activated by muscarine metabotropic
72
Muscle-type Nicotinic acetylcholine receptors
found at the neuromuscular junction (NMJ) role in contractile muscle also a Pentamer with 2 ACh binding sites
73
Nicotine Acetylcholine receptor pentamer subunits are made out of what?
M1,M2,M3,M4 subunits
74
Myasthenia Gravis (MG)
It occurs when the immune system attacks nicotinic acetylcholine receptors (nAChRs) at the neuromuscular junction (NMJ), preventing proper muscle activation.
75
Glutamate receptors ionoconic
AMPA, KAINATE, NMDA (all glutamate analogs) Mg block/depolarization req.
76
metabonic glutamate receptors
mGluRs: mGluR1-mGluR8
77
GABAA receptors
Inhibitory effects,Pentameric structure
78
inhibitors of Glutamate
Anticonvulsants: -Block Na+ channels -GABA agonists open Cl- channels - hyperpol

From cells to organisms (22 decks)

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