2.6. Chemical signaling 2, life cycle Flashcards
Outline the target cells of hormones, neurotransmitters, cytokines, and Ca ions.
Hormones - All cells, Neurotransmitters - Postsynaptic neuron, Cytokines- The cell that produces them or a nearby cell, Ca ions - The same cell that pumped them out
Outline how they affect their TC for hormones, neurotransmitters, cytokines, and Ca ions.
Hormones - Inhibiting/promoting processes, Neurotransmitters - Either excites or inhibits transmission of an impulse, Cytokines - Changes in gene expression and cell activity, Ca ions - Cause presynaptic neurons to release neurotransmitters
Outline the speed/longevity of the effect of hormones, neurotransmitters, cytokines, and Ca ions.
Hormones - Long-lasting effects (minutes/hours), Neurotransmitters - Short-lived effects (faction of a second), Cytokines - Short-lived effects
Give examples of hormones, neurotransmitters, cytokines, and Ca ions.
Hormones - Insulin, thyroxin, testosterone, adrenaline Neurotransmitters - Adrenaline, dopamine, Cytokines - Erythropoietin (EPO), interferon, interleukin
Which ligand has the most widespread effect and which is the most profound?
hormones, cytokines
To which receptor does cytokine bind and why?
only to transmembrane receptors – hydrophilic, cannot cross the PM
Explain the variability of cytokines (in terms of source and effect).
One cytokine may be secreted by different cells (some by almost any) and different cytokines can be secreted by one cell. The same cytokines can bind to different receptors on a single cell (producing different effects).
What is the role of cytokines in the body?
1| Inflammation and other immune system responses
2| Cell growth and proliferation control
3| Development of embryos
What is the role of Ca ions in the body?
1| Neurons - cause presynaptic neurons to release neurotransmitters into the synapse
2| Muscles - causes muscle fibers to contract
Describe and outline the effect of the GPCR process.
G protein-coupled receptors (GPCRs) – a large and diverse group of transmembrane receptors.
G protein (GP) - a second protein located in the PM.
The three subunits of GP and a mol of GDP which keeps it inactive, assemble on the surface of the cytoplasm side of receptor
When ligand binds on the extracellular side, receptor conformational changes are triggered, which causes changes in the GP - GDP is replaced with GTP (ADP phosphorylated to create ATP) which activates the GP - it separates into its subunits and dissociates from the receptor.
GP subunits cause further interactions within the cell (bind to effector proteins), leading to actions that are the cell’s response to the signal brought by the ligand
- e.g. binding of adrenaline - activates GP - activates adenylyl cyclase - converts ATP into cyclic AMP - initiates a sequence of rapid responses inside the cell
- e.g. liver cells break down glycogen and release glucose into the blood in seconds
What is bioluminescence? Which organisms can perform it? What is its purpose?
- a metabolic process in some organisms that produces light (biological light production).
- bacteria, fungi, animals (marine vertebrates (crabs, jellyfish), fireflies, glowworms, anglerfish, lantern fish)
- to attract prey and mates, communicate, distinguish each other in groups, evade predators by mimicking sunlight, provide light for symbiotic organisms (algae), reproduction (mushrooms attracting insects that’ll help them expand their habitat), pigments to protect them from the sunlight (in more shallow waters).
How is bioluminescence produced (the reaction and organisms involved)?
Vibrio fischeri (bacteria that can perform bioluminescence) – can be free-living or symbiotic bacteria. Light production is the byproduct of luciferin oxidation:
Luciferin (luciferase) -> … + green/bluish light (because it has specific wavelength)
What is quorum sensing?
A method by which single-celled organisms measure the density of their population. Process of cell-cell communication that allows bacteria to share information about cell density and adjust gene expression accordingly.
What are signaling molecules also called? Why?
autoinducers…
What is a life cycle? Sketch and annotate it.
a repetitive sequence of events between two cell divisions that enables cell proliferation
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