secretion in a cell Flashcards
what is a phagosome
vesicle formed around a particle engulfed by a phagocyte via phagocytosis
which process involves smaller invaginations of the cell membrane which fuse and entrap extracellular fluid and its dissolved contents.
pinocytosis
do pinocytotic vesicles pinch off from the membrane
yes
what is transcytosis
type of transcellular transport in which various macromolecules are transported across the interior of a cell
during receptor mediated endocytosis what do the the vesicle invaginate as
coated vesicle
what is the major polypeptide that coats the vesicles during receptor mediated endocytosis
clathrin
what do the clathrin molecules interact with
struts of a geodesic dome
what are caveolae
invaginations produced by type of receptor-mediated endocytosis prominent in very thin cells
where do the vesicles fuse in receptor mediated endocytosis after pinching off from the membrane
they fuse with the endosomal compartment
what is a dynamic collection in the peripheral cytoplasm of membranous tubules and vacuoles
endosomal compartment
which diverse peripheral proteins are caveolins associated with
cavins
the clathrin molecules separate from the coated vesicles and are thrown away. true or false
false, they are recycles back into the membrane to form new coated pits
what is the function of Rab proteins (G proteins) in the endosomal compartment
directs vesicle trafficking along small GTPases that bind guanine nucleotides and associated proteins
what enzyme binds guanine and associated protein during vesicle trafficking
GTPase
what triggers exocytosis
increase in cytosolic Ca ions
Membrane fusion during exocytosis is highly regulated, true or false
true. selective interactions between several specific membrane proteins
which secretions is used for products that are released from cells continuously, as soon as synthesis is complete
constitutive secretions.
when do regulated secretions occur
in response to signals coming to the cells, such as the release of digestive enzymes from pancreatic cells in response to specific stimuli
what secretions are used for collagen subunits in the ECM (extracellular matrix molecules)
constitutive secretions
what is an example of regulated secretion
release of digestive enzymes from pancreatic cells in response to specific stimuli
where does regulated exocytosis of stored products from epithelial cells usually occur
apical domains of cells, constituting a major mechanism of glandular secretion
what are the three exocrine glands
apocrine
merocrine
holocrine
which type bud their secretions off through the plasma membrane producing extracellular membrane-bound vesicles
a) merocrine
b) apocrine
c) holocrine
apocrine.
merocrine- secretions of that cell are excreted via exocytosis from secretory cells into an epithelial-walled duct or ducts and then onto a bodily surface or into the lumen
holorcine- secretions released by the rupture of the plasma membrane, which destroys the cell and results in the secretion of the product into the lumen
what is process of membrane movement and recycling called
membrane trafficking
what is the importance of membrane trafficking
for physiologically important processes such as reducing blood lipid levels
what is endocrine signaling
involves a signaling molecule, a hormone, secreted by an endocrine cell and transported through the circulation to act on distant target cells
what is paracrine signaling
mediated by a molecule acting locally to regulate the behavior of a nearby cell
what is autocrne signaling
cells responding to signaling molecules that they themselves produce
name the two types of paracrine signaling
- Neurotransmitter or synaptic cell signaling
2. Juxtacrine cell signaling is contact dependent signaling
what is an example of neuroendocrine signaling
Norepinephrine acting on hepatocytes or adipocytes
give an example of paracrine signaling
Glucagon and somatostatin acting on adjacent cells of the islets of Langerhans that secrete insulin
give an example of juxtacrine cell signaling
immunologic synapse when antigen-presenting cells and a T cell are in contact with each other
give an example of autocrine signalling
response of cells of the immune system to foreign antigens or growth factors that trigger their own proliferation and differentiation
what does abnormal autocrine signaling cause
unregulated growth of cancer cells
what regulates the release of a targeting hormone
negative or positive feedback action
name four major intracellular signaling pathways
cAMP
Ca calmodulin
JAK-STAT
integrin actin pathway
name four more intracellular signalling pathways
cGMP
phospholipid Ca pathway
Ras, Raf and MAP kinase pathway
NF-κβ transcription factor pathway
what is the effector protein for cAMP
adenyl cyclase
DAG and IP3 are examples of what
secondary messengers
what do ionic changes or second messengers do
amplify the first signal and trigger a cascade of enzymatic activity
what enzyme is usually activated during cascade effects
kinase (enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates)
what leads to more focused amplification of activity.
when 2nd messengers retained locally by scaffold proteins
