active membrane transport process=
characteristic=
types of solutes/conditions it is used=
2 types=
ALL require ATP
-against [] gradient
-too large for channels
-not lipid-soluble
vesicular transport
active transport
active transport
desc. structure and how it works (what is required?)
_ transports more than 1 substance
req. carrier proteins.
substance binds specifically to carrier protein= conf. change= solutes move
symporters, antiporters
symporters=
transport type=
carrier protein for secondary active transport
2 diff solutes move in same direction
antiporters=
transport type=
type of transporter carrier protein
secondary active transport
2 diff solutes move in opp direction: one in one out
primary active transport
active transport (move against electrochemical gradient) that DIRECTLY requires/uses ATP hydrolysis
secondary active transport=
EX:
common solutes=
active transport that uses energy from [] gradient of a different solute that was directly created by ATP hydrolysis (primary active transport)
sodium/glucose transporter: sodium is pumped against [] by a Na/K pump. as sodium DIFFUSES across membrane, brings glucose with it
sugars, ions, a.a. (per TA, technically can be transported via facilitated, but most usually through secondary active transport)
how does ATP hydrolysis allow solute to move against gradient?
energy released from ATP hydrolysis
= conf. change
=solutes pumped across :)
sodium pot. pump
desc=
location=
desc= enzyme Na+/K+ ATPase pumps 3 Na+ out, 2K+ in
location= ALL plasma membranes, but especially active in excitable cells (ex: nerves and muscles)
leakage channels=
affect on membrane potential=
channels that allow mvmnt of substances. *ions move according to electricalchemical gradient (based on concentration and charge of ions)
cause Na+ leak into cell, K+ leak out of cell
maintains electrochemical gradient
expl. GENERAL steps of Na/K pump
- ATP and Na+ binds
-ATP hydrolysis= Conf change
-Na+ released
-K+ bind
-P released
-K+ released
Does vesicular transport req ATP
YESSSSSS
types of vesicular transport (4)=
endocytosis
exocytosis
transcytosis
vesicular trafficking
types of endocytosis (3)
phagocytosis
pinocytosis
receptor-mediated endocytosis
transcytosis
endocytosis
(desc. vesicle's characteristics; what happens to the vesicle?)
PROTEIN coated vesicles form
vesicles become uncoated
usually involves receptors
they either:
fuse with lysosome
undergo transcytosis
phagocytosis
desc. vesicle formation and migration
solutes
EX of phagocytic cells
pseudopods (membrane projections) surround particle
vesicle= phagosome
phagosome combines with lysozome
may/may not be protein coated
large or solid particles
EX: WBC, macrophages
pinocytosis
desc. vesicle formation and migration
EX of pinocytosis cells
membrane infolds
fluid/dissolved particles
EX: located in cells that line small intestine (absorption)
Specificity of phagocytosis vs pinocytosis
phagocytosis: more specific. usually contain receptors
pinocytosis: nonspecific. NO receptors
transcytosis
via vesicular transport: moves substances into, across, and then out of cell
receptor mediated endocytosis
solutes (NOT SURE HAVE TO KNOW FOR TEST)
fates:
MAIN MECHANISM for specific endocytosis and transcytosis
large proteins (enzymes, insulin, hormones), LDL, iron, viruses, cholera, etc
fates
released inside cell
digested by lysosomes
moved across the cell and then out of cell
Desc. docking process in exocytosis
V-Snare on vesicle
T-Snare on plasma membrane
V-Snare and T-Snare hook together= exyocytosis
substances exocytosed
hormones, neurotransmitters, cellular waste, mucus
polarized cells
applies to which cells?
cells that have a charge (there is a difference in electrical charge across membrane)
ALL cells (all cells have RMP<0)
resting membrane potential occurs at
ONLY membrane surface.
fluid or the rest of the cell= electrically neutral
desc "key player(s)" (solutes) that lead to RMP.
which is more important? why?
-KEY PLAYER: K+
K+ driven out of cell by leaky channel diffusion
BUT K+ driven into cell by electrical gradient (neg)
-other player: Na+
driven to diffuse into cell b/c concentration AND electrical gradient
-K+ more imp b/c membrane more permeable to K+ than Na+
when is RMP established?
when flow of K+ into cell= flow of K+ out of cell
Why does Cl- NOT contribute to RMP
electrochemical gradient is EXACTLY balanced
through what process/function is RMP maintained?
Na/K pump pumps 3 Na+ out, 2 K+ in
Why does steady state able to be maintained if there is an unequal [Na+] across the membrane?
active pumping of Na+ out of cell= rate of Na+ diff into cell
how is RMP disrupted
opening of GATED ion channels (Na+ and K+)
how do cells interact with env (directly, indirectly)
directly to cells
or indirectly to env
role of glycocalyx in cells=
main types=
REQUIRED for ALL interactions of cell with other cells and cell with environment
CAMs (cell adhesion molecule)
Plasma membrane receptors
CAM
cell type=
func=
glycoprotein
"velcro"- anchors cells to each other and to ECM
"arms"- help cells move past each other
"SOS!!!"- attract WBC to injured/infected area
"sensor"- detect and respond to changes in local tension/ fluid mvmnt at cell suface THEREFORE stimulates synthesis/degradation of adhesive junctions (ex: tight junctions)
"signal"- transmit intracellular signals that direct cell migration, proliferation, and specialization
STORY: "CAM!! SOS! come here! Being a mother I sensed something was wrong with my cell phone signal so had to use this dumb velcro arm to get your attention.
plasma membrane receptors=
cell type=
func=
membrane receptors that serve as binding site for signals
glycocalyx (Text desc. it as glycoproteins)
contact signaling
chemical signaling
desc. contact signaling of plasma membrane receptors
func=
important in=
cells tough each other through the receptors
cell recognition
normal development and immunity
desc. chemical signaling of plasma membrane receptors
func=
important in=
receptor-ligand (chemical messenger) interaction
cause changes in cell activities (through enzyme activation, open ion channels, etc...)
binding of neurotransmitters, hormones, paracrines (chemicals that act locally and are rapidly destroyed)
GPCR
func=
MAIN steps=
acts as "middleman" btwn extracell. 1st messenger and intracell 2nd messenger
1. ligand-receptor binding= G-protein activation
2. G-protein activates protein= 2nd messenger produced
- Ex: cAMP, calcium
3. 2nd messenger activates enzyme (usually protein kinase, which phosphorylates using P of ATP)
HW: True of False: In their resting state, all body cells exhibit a resting membrane potential; therefore, all cells are polarized. EXPL
True. All cells have RMP<0, therefore is polarized (polarized is then there is a difference in charge across the membrane)
HW: Which transport process is the most common way of intaking macromolecules into the cell
receptor- mediated endocytosis
HW: True or False:
A resting membrane potential is a sign of a depolarized membrane.
False.
at RMP: cell is polarized.