Lecture 5 Flashcards
cystic fibrosis
a genetic disorder
mutation in a gene encoding a chloride channel
so distrust the transport of Cl ions across cell mb
leads to thick sticky mucus buildup in lungs + GI sys
no channels = Cl- can’t get out= bc CL usually helps draw water out of cells = mucus is kept thin w water = now Cl isn’t getting out = water stays and get pulls in = mucus gets dehydrated = gets thicker and sticky = accumulates in lungs and pancreas
Cl stuck in cell, water can’t get out,
main protein types for transport of inorganic and small org molecs across mb
channels (water nad ion channels)
= most are ion channels
= form tiny h philic pores allow substances to pass by diffusion
transporters (active and passive)
against + w E and with + w/o E
most imp ions + which the cell wants in
Na, K, Cl-, Ca+2
cells wants,
High K inside the cell
rest high outside
rest is kept low inside cell so when conc inc = is a signal for the cell (ex. when muscle contraction)
charges w in cell + mb
Electrical charges are balanced in and out
small charge diff on both sides of plasma mb
more (-) inside than out = mb potential
imp for movement of charged molecs
diffusion
molecs go from high conc to low
w gradient, no E
not charged, det by conc
electrochemical gradient
inorganic ions or charged molecs det by charge differences
passive, no E required
ion channels are very selective
what distinguishes them from pores
most channels are ion channels
narrow and highly selective
= narrow opening w small D limited larger molecs from entering
but they facilitate passage of select inorg molecs
distinguished by = ion selectivity + open/closure states
= not always open = fluctuates bn open and closed
gated ion channels
what + 3 types
specific stim needed to trigger them to switch bn open and close
voltage gated = controlled by changes in voltage across mb
mechanically = controlled by physical stim = light/sound waves, P, stretch, touch, vibrations
ligand = by binding of a molecule, always closed but opens when binded
osmosis
diffusion of water across mb from low solute to high solute
low solute = high water
high solute = low water
so high to low water
through aqaupoin channels in plasma mb
spec for water
transporters for small molecs or inorganic ions
diff from ions tho
bc they change confomariton to transport across mb
can move on substance = uniporters
or 2 substances
= same direction = symporters
= diff directions = antiporters
some can use E to go against gradient
types of E sources used in active transport
light
ATP
electrochemical gradient
primary vs secondary active trasnporter
primary = the transporter that uses ATP and creates an electrochemical gradient ex. Na-K pump
requires E
secondary = uses the gradient fromed by the other
ex.
Na/K pump,
primary = hydrolyzes ATP, moves Na, from low to high, against conc gradient
secondary = now w the high conc of NA out, and low in, Na moves w conc gradient, goes in cell, + drives transport of glucose against conc grad
active and passive in glucose transport across api lining of the gut
first, conc grad of glucose, goes low, high, low
from gut lumen, epi layer, ECF
so active transport, symport, w Na,
then passive,
bc first, from low to high
then high to low
plant vs animal transporter
animals = na pump, na driven symport
plants = same but w H
so H sets up a gradient
endocytosis and exocytisi
too large, too charged to pass through
endo = 3 types
= receptor mediated, pinocytosis, phagocytosis
receptor mediated + LDL repupathe
LDL transports cholesterol int he blood
- LDL receptor on cell surface binds LDL particles in the blood
- mb buds off formes vesivles
- fuses w endosomes
- LDL receptors retuned to plasma mb
- LDL give to lysosomes
- cholesterol is extracted from LDL
- the rest, proteins/phospholipids etc are left behind
