Lesson 3: Chemical Signalling Flashcards
(19 cards)
Correlation between body mass and speed of neurone Impulses.
Larger body mass correlates with slower neuron impulse speeds due to longer distances signals must travel.
what are ligands?
signalling molecules
Types of signaling molecules
Hormones
Neurotransmitters
Cytokines
Calcium Ions
Explain the mechanisms of quorum sensing in marine bacteria.
A process by which bacteria communicate cell density to one another.
Quorum sensing bacteria secretes ligands called autoinducers into the extracellular matrix.
They can diffuse back into the cell and neighbouring cells.
At high cell density, concentration of autoinducers are also high causing diffusion into cells.
If autoinducer concentration reaches above a threshold concentration, they bind to internal receptors triggering a change in gene expression.
This leads to coordinated behaviours such as bioluminescence and biofilm formation.
´
Behaviors regulated by quorum sensing
Biofilm Formation and Bioluminescence.
Applications of quorum sensing.
Prevent biofilm formation.
Break down pollutants.
Prevent food spoliage.
What are the four signalling chemicals in animals?
Hormones
Neurotransmitters
Cytokines
Calcium ions
Define autocrine signalling
Signals act on the same cell that secreted them.
Define paracrine signalling
Signals act on nearby cells.
Define endocrine signalling
Signals (hormones) travel through the bloodstream to distant target cells.
What are the 4 modes of signalling?
autocrine
paracrine
endocrine
contact-dependent
Define contact-dependent signalling
Cells must be in contact to transmit signals.
What are the different types of hormones and an example for each.
Peptides - insulin
Steroids - testosterone
Amino acids - epinephrine
Characteristics of hormones
Long-distance signaling, slow and sustained effects.
Characteristics of neurotransmitters
Rapid, short effects and short-distance signaling
Compare and contrast transmembrane receptors and intracellular receptors.
Transmembrane Receptors:
Located on the cell membrane.
Bind to hydrophilic ligands
Intracellular Receptors:
Located inside the cell (cytoplasm or nucleus).
Bind to hydrophobic ligands
Explain how G proteins are activated.
A ligand binds to the GPCR causing a conformational change and activating it.
GDP is replaced by GTP at the G protein, which activates it.
Broken up G protein interacts with other molecules to trigger a cellular response.
Explain mechanism of action of epinephrine receptors.
Binds to GPCR causing a conformational change.
G protein replaces GDP for GTP.
G protein activates enzyme adenylate cyclase.
Converts ATP to cAMP.
Activates other molecules > different physiological changes.
Explain how insulin and RTK lead to cell response.
Insulin binds to the receptor tyrosine kinase (RTK), causing a conformational change that brings the two intracellular tails together.
The two tails phosphorylate tyrosine residues on each other.
Leads to cascade.
