3- secondary Active transport (11 Oct) (2different types of transporters…
3- secondary Active transport (11 Oct)
1- the transfer of Na across the epithelial cells
also the transfer of Glucose is critical
eg. of the import. of the co transporter mechanism
high conc. of glucose in the intestinal lumen
we want to transfer those across apethelial cell into the intertitial space to be absorbed by the body
3 Na+ going in = down conc. grad.
because the conc. grad. of Na is kept low because of Na-K pump
that brings the transfer of glucose into the cell as well
glucose can be transported through a channel across into the interstetial space
this is another example of the differential expression of channels and transporter proteins on the apical and basolateral surface that allow the facilitation of the transcellurar mov. of substances like glucose across those cells
2different types of transporters
Sodium - potassium - chloride cotransporters
transporting all Na+ and K+ and Cl - across the membrane
potassium chloride co transporters
moving them across the cell
3- how effective transporters are in accumulating solutes against their con. grad.
in vitro experiment
created little vesicles from epithelial c.
Na Glucose transporter on the surface
high conc. of Na and Glucose
transport those into the c.
graph represents the transfer rate or the amount of Glucose uptake thats achieved when we have a Na-Glucose transported - the measurement over time
very high accumulation of glucose in a very rapid time - against its conc. gradient
if we block or inhibit transporter proteins
get the movement of glucose into the cell but slow in relation to the transferrate in the presence of Na-Glucose transporter
4- another example
the ability to maintain very low intracellular conc. of Ca.
the intracellular conc. of ca.
depending on the type of cell
can activate various proteases
and causes quite destructive damage to the cell
depending on which pathway is activated
muscle or nerve cell:
we need short but dramatic increase
in conc. to activate those cells
muscle contract=burst of Ca being released
Ca needs to be pumped away
quickly so the muscle can relax again
often have large changes in intracellular Ca conc.
2 more items...
other cells activation of protease and degredatin of proteins
need to keep it low and regulate it tightly
some of the processes involve co transporters
to regulate intra cellular conc. of Ca
Hydrogen Calcium exchange
a pump that fueled by hydrolysis of ATP
transp. H ions into the cell
Ca ions outside of the c.
Na - Ca exchanger
a carrier co transport process
Na coming into the cell down its conc. gradient
facilitate the transfer of Ca out of the cell against its conc. gradient
very important pumps inthe endoplasmic reticulum
or sarcoplasmic reticulum in skeletal muscles
example: sarcoplasmic reticulum Ca pump
got hydrolysis of ATP
pumping Ca into the cell
also we have the presence of Ca binding proteins that help to
bind to Ca when it comes in and facilitates the accumulation of Ca.
3 more items...
extrude Ca+ from the cell
Na-Ca Pump (pump is missing from the slide)
Na-Ca exchanger (Na-Ca is missing from the slide)
the typical intracellular vs extra cellular
low inside compared to the outside
5- diagram = 1 to 19 in 2 slides
reperesents a large no. of types of transport mechanisms that are present in the cells
cells in our body express different types of transporter proteins
in every cell there is abundant of these processes that are going on at any one time
1- active transport processes:
using ATP at constant rate
high energy demand for pumping these ions across the memb.
to maintain intracellular conc. of Na and k. k
2,3,4- specialised channels that can selectively transport particular solutes and specific for transport of specific ions
different gating mechanisms- we can regulte the opening and closing of those
5- co transporters- utilising the Na conc. grad. to transport solutes like amino asid and Glucose aginst their conc. grad
8,9- Ca regulating channels and pumps that keep the intra cellular Ca low- they are expressed on plasma memb. but also specialised ones in the membranes of the organells inside the c. (7)
different processes involed in regulating of tran. of these solutes across memb. from one side to the other
with mutation to the ion channels the impact to cellular func. is dramatic
very big proteins and molecules
we need across the membrane
presence of the carrier in the surface
express them on the surface of the plasma memb.
ARE NOT SUFFICIENT
other processes to allow endo cytosis and exocytosis
mechanisms by which we can move very large proteins
and molecules across the membrane
formation of protein in endoplasmic reticulum
transported to the golgi apparatus before it secreted by scretary vesicles
those processes require endocytosis of those molec. from one structure to another
uptake of large molec. and protein
mediated by endocytosis
transfer to organells like lysosome
to be degredated or brocken down