CS - L1 Flashcards
Why is cell signalling needed?
To ensure survival?
What is cell signalling?
A complex system of communication
What does cell signalling govern?
basic cellular activities and coordinates cell actions
Cell signalling affects a cell’s ability to…?
Regulate cellular processes & respond to its environment
What is regulation of cell processes and cell signal responses important for?
Development, tissue repair, cell growth/division, immunity, movement and diseases
What does cell survival depend on?
Receiving and processing information from the environment
A cell is exposed to multiple different extracellular signal molecules - does it respond to them all?
No
Why is cell signalling important at an organism level?
development -> specialised cells -> coordinated response
What are potential results of defects/dysregulation in signalling pathways?
Diseases - cancer, diabetes, etc.
What occurs in the absence of signals
apoptosis
Why is constant signalling required?
cell survival
What is Wnt signalling involved in?
embryonic development (heart, bone, etc)
What occurs if Wnt is disrupted/dysregulated
cancer (colorectal cancer)
What determines the type of signalling a cell uses?
distance between the cells
What are the 5 basic types of signalling used?
Gap junction, APC , neurotransmitter, auto/paracrine, hormone
What are gap junctions
cytoplasmic channels between adjacent cells - connects cytoplasm
What does the gap junction do?
maintains homeostasis in connected cells for ion balance & allows passage of signal molecules
What does gap junction provide?
metabolic cooperation between adjacent cell
What are the receptors required for CD4?
MHC2
What is common between autocrine and paracrine signalling
ligands produced by cells that travel through extracellular fluid
What cell is the cell signalling to in autocrine?
Itself
Give examples of an autocrine signalling
IL-1 secreted by monocytes as a response to external stimuli
Secretion of growth/survival factors by tumour cells
IL-2 in T cells
What cell is the cell signalling to in paracrine?
Neighbouring cells
Give examples of paracrine signaling
Wnt and hedgehog & inflammatory mediators
What is tumour cell migration controlled by?
Paracrine loop
What occurs during the paracrine loop?
Tumour Associated Mq make EGF (epidermal growth factor) -> EGF binds to EGFR on invasive breast tumour cell -> Invasive tumour cell makes CSF1 (colony stimulating F1) binds to CSF1R on TAM
What do neurotransmitters trigger in cells/target tissues?
Responses
Where does the nuerotransmitter go after use?
Remains in the synapse
What happens to the neurotransmitter after its been used?
Broken down
What determines the specificity of neurone signalling?
synaptic contact between neurone and target cell
What is the advantage in neurone signalling compared to direct contact
control the amount of signal travels by inhibition
What are the 4 ways cells communicate if they’re close to e/o and give examples
contact-dependent (APC & CD4)
autocrine signalling (IL2 and CD4)
paracrine signalling (TAM and invasive breast tumour cell)
Synaptic signalling (neurone & target cell) SOMETIMES, can be distant
How do cells communicate long distance
endocrine (hormones)
spec. - receptors
synaptic signalling
spec. - synaptic contacts
most signals are ____
chemicals
signals act at very ____ conc. -> signal _____
LOW, amplification
How are signals recognised?
by receptors with high affinity
A cell must respond _____ to a mixture of signals, disregarding some and reacting
to others, according to the cell’s specialised function
selectively
What does the cell need in order to respond to a signal?
A receptor
How does the cell restrict the range of signals that can affect it?
By producing a limited set of receptors
What are the 3 steps of cell signalling and what factors are involved?
- reception - > receptors
- transduction -> signal transducers
- cell response -> effector proteins
What is the function of transducers?
relay, integrate and distribute signals
SIgnalling pathways regulate _____ cellular functions
nearly all
What are the characteristics of cell signalling?
specificity
integration and coordination
amplification
feedback
How is specificity maintained in cell signalling?
receptors.
specific receptors are ____ in distinct cell types
expressed
What should happen if 2 or more signals have opposite effects on a metabolic pathway?
Outcome result should reflect the integration of these signals
Why should the outcome of multiple signals reflect the integration of these signals?
coordinated response
What can signalling interfere with?
core physiological processes
What’s the role of a feedback loop?
desensitisation/adaptation
What can the feedback loop do?
Modify the signal and the output to regulate the process
What happens during deactivation?
degradation.recycling of molecules
What happens during activation?
Adjust sensitivity. under prolonged exposure to reduce cell response’s to that level of stimulus
What are the 5 basic types of signalling
APC, GAP junction, NT auto/paracrine, endocrine
