CELL 3 Flashcards
what is vesicular transport
using vesicles to move substance into / out of cell
what are 3 types of vesicular transport
- endocytosis
- exocytosis
- trasncytosis
ENDOCYTOSIS what is endocytosis
using vesicles to bring molecules into cell
ENDOCYTOSIS what are 3 types of endocytosis
- phagocytosis
- pinocytosis
- receptor-mediated endocytosis
ENDOCYTOSIS what is brought into cell in phagocytosis
- bacteria
- large particles
(cell debris from damaged tissue)
ENDOCYTOSIS what are the steps of phagocytosis (5)
- pseudopodia surround bacteria or large particles
- vesicle pinches off from mem + internalized
- phagosome migrates to lysosome
- phagosome duses w lysosome
- vesicle contents digested by lysosome’s digestive enzymes
ENDOCYTOSIS what is internalized vesicle in phagocytosis called
phagosome
ENDOCYTOSIS what type of cell does phagocytosis
macrophages
ENDOCYTOSIS what do macrophages use phagocytosis for
- destroy bacteria
2. destroy cell debris found in blood
ENDOCYTOSIS what is brought into cell in pinocytosis
- solutes
2. water
ENDOCYTOSIS where do solutes and water that are brought in by pinocytosis come from
ECF
ENDOCYTOSIS what are the steps of pinocytosis (2)
- mem invaginates
2. pouch pinches off to form vesicle
ENDOCYTOSIS how is pinocytosis diff from phagocytosis
- pinocytosis does not use pseudopodia
- pinocytosis is non specific
- pinocytosis does not engulf large particles
- many cells in body do pinocytosis
ENDOCYTOSIS what are the steps of receptor mediated endocytosis (9)
- ligand binds to receptor on surface of PM
- clathrin links to receptor-ligand complex through adapter proteins
- clathrin- receptor- ligand complex forms cage-like structure
- receptor-ligand complexes accumulate in localized region of mem
- mem indents to form clathrin coated pit
- clathrin coared pit pinches off from mem to become clathrin coated vesicle
- vesicle loses clathrin coat
- clathrin recycles back to mem
- uncoated vesicle fuses w intracellular mems
ENDOCYTOSIS what organelle does uncoated vesicle often fuse with
endosome
ENDOCYTOSIS what happens when uncoated vesicle fuses w endosome
receptor + ligand dissociate
EXOCYTOSIS what are 3 functions of exocytosis
- secrete mem impermeable molecules that are synthesized by cell
- secrete waste products that cannot be digested
- replace portions of memm removed by endocytosis
EXOCYTOSIS why must endocytosis and exocytosis be balanced
to maintain overall size of PM over time
EXOCYTOSIS what are the steps of exocytosis (5)
- vesicle migrates to surface
- vesicle docks on peripheral mem proteins
- proteins pull PM inwards to form dimple
- dimple fuses w vesicle
- vesicle releases contents into ECF
TRASNCYTOSIS what is trasncytosis
using endocytosis and exocytosis to move receptor -bound molecule through cell
TRASNCYTOSIS what type of cell does trasncytosis
polarized cells
TRASNCYTOSIS what are polarized cells
cells w diff mems on its 2 sides
TRASNCYTOSIS what is best studied example of trasncytosis
absorption + transport of antibodies across epithelial lining of gut
TRASNCYTOSIS what are the steps of trasncytosis (8)
- antibody absorbed
- antibody binds to receptor on apical surface of intestinal cell
- antibody internalized by receptor mediated endocytosis
- receptor + antibody go to endosome
- receptor+ antibody go to recycling endosome
- receptor+antibody go to basal surface of cell
- receptor + antibody dissociate
- antibody enters blood
DRIVING FORCES what are 3 types of driving forces
- chemical
- electrical
- electrochemical
CHEMICAL DRVING FORCE when does conc gradient for substance exist
diff in conc of substance across mem
CHEMICAL DRVING FORCE what type of driving force is concentration gradient
chemical
CHEMICAL DRVING FORCE what direction do molecules of substance move
down conc gradient
CHEMICAL DRVING FORCE what direction is chemical driving force when there is higher conc inside than outside
directed out cell
CHEMICAL DRVING FORCE what direction is chemical driving force when there is higher conc outside than inside
directed into cell
CHEMICAL DRVING FORCE what happens as the size of conc gradient increases
- increase driving force
2. increase rate of transport
CHEMICAL DRVING FORCE what happens to potential energy as gradient eliminated
disappears
ELECTRICAL DRIVING FORCE why do electrical driving forces come about
mem potential
ELECTRICAL DRIVING FORCE what is mem potential
diff in electrical potential / voltage across mem
ELECTRICAL DRIVING FORCE what does mem potential reflect
unequal distribution of cations + anions across mem
ELECTRICAL DRIVING FORCE what does separation of charge refer to
unequal distribution of charges across mem
ELECTRICAL DRIVING FORCE as ion crosses mem what is it attracted to
net electric charge on one side of mem
ELECTRICAL DRIVING FORCE as ion crosses mem what does it repel
net electrical charge on other side of mem
ELECTRICAL DRIVING FORCE what does electrical driving force add to / subtract from
other driving forces that may be present
ELECTRICAL DRIVING FORCE what do electrical driving forces not act on
uncharged substances
ELECTRICAL DRIVING FORCE when is glucose transport affected by mem potential
when glucose coupled to movement of ion
ELECTROCHEMICAL DRIVING FORCE what are ions influenced by
- chemical driving force
2. electrical driving force
ELECTROCHEMICAL DRIVING FORCE what is electrochemical driving force
sum of chemical and electrical driving forces acting on ion
ELECTROCHEMICAL DRIVING FORCE what is direction of electrochemical driving force
- net direction of electrical + chemical driving forces
- if both in same direction ==> sum
- if both in opposite direction ==> diff
CHANNELS what are characteristics of channels (6)
- multi meric proteins
- form pore that spans bilayer
- substrate specific
- exist in open or closed state
- allow for rapid movement
- can function as receptors
CHANNELS what is able to move through channels (2)
- ions
2. ion water complexes
CHANNELS what are aquaporins
channels that allow only water to pass through
CHANNELS what states do channels exist in
- open state
2. closed state
CHANNELS wha happens in open state
ion flow
CHANNELS what happens in closed state
no ion flow
CHANNELS why is there rapid movement across channels
low resistance pathway
CHANNELS why are channels able to act as receptors
able to bind ligand
CHANNELS what are channels that bind ligands called
ligand-gated ion channel
CHANNELS what happens when transmitter binds to receptor
- protein changes shape
2. protein allows flow of ions
CHANNELS what alters state of channel
ligand