ch 6 Flashcards
Phosholipid
- bilayer
- amphipathic (hydrophilic head, hydrophobic tail)
- hydrophobic barrier: keeps hydrophilic molecules out
Cell membrane
plasma membranes are selectively permeable
selectively permeable
allow some substance to cross more easily than others
small molecules cross easily (hydrocarbons, co2 o2 )
hydrophobic cor prevents passage on ions, large polar molecules
fluid mosaic model
FLUID: membrane held together by weak interactions
MOSAIC: phospholipids, proteins, carbs
two kinds of membrane proteins
integral and peripheral
integral proteins
embedded in membran
determined by freeze fracture
transmembrane with hydrophilic heads/tails and hydrophobic middles
peripheral proteins
extracellular of membrane
not embedded
held in place by ecm
provides stronger framework
functions of membrane proteins
transport enzymatic activity signical transduction cell to cell recognition intercellular joining attachment to the cytoskeleton and ecm
Passive transport
no energy needed
diffusion (down concentration gradient)
High to low concentration
e.g.. co2 o2 h2o
carbohydrates functions
cell to cell recognition and developing organisms
examples of carbs in cell membrane
glycolipids, glycoproteins
blood transfusion and type specific
diffusion
spreading of something more widely
what does diffusion do
reach equilibrium
the freeze fracture method
revealed the structure of membranes interior
how do cells arrange themselves in groups?
cell recognition
cell adhesion
(integral glycoproteins)
fibers of ecm
collagen
fibronectin
proteoglycan complex
cholesterol
helps with fluidity inside membrane
carrier protein example
glucose transport protein
osmosis
diffusion of water (high to low)
active transport
requires energy (ATP)
proteins transport substances AGAINST concentration gradient
low to high
eg. sodium potassium pump, proton pump
the potassium channel
custom fit for potassium
potassium is attracted by the negative oxygen atoms in protein
hypertonic
high solute causes cells to shrivel
isotonic
neutral
hypotonic
low solute causing cells to swell
three types of proteins for active transport
uniporter
symporter
antiporter
uniporter
transports one substance in one directions
symporter
transports two different substances in the same direction
antiporter
transports two different substances in opposite direction
aquaporin
channel protein that allows passage of water
facilitated diffusion
requires transport proteins help hydrophilic substances cross two ways: provide hydrophilic channel loosely bind/carry molecule across eg. water, glucose ions polar molecules
what are transport proteins
channel or carrier proteins
electronic pumps
generate voltage across membranes
eg. sodium potassium and proton pump
sodium potassium pump
pumps sodium out and potassium into cell
nerve transmission
proton pump
pushes protons (H+) across membrane ex. mitochondria (ATP production)
cotransport
membrane protein enables “downhill” diffusion of one solute to drive “uphill” transport of other
eg. atp production in plants
Passive transport
little to no energy
high to low concentrations
down the concentration gradient
eg. diffusion, osmosis, facilitated diffusion (w/ transport protein)
active transport
requires energy (ATP)
low to high concentration
against concentration gradient
eg. pumps, exo/endocytosis
bulk transport
transport of proteins, polysaccharides, large molecules
eg.
endocytosis
exocytosis
endocytosis
take in molecules, form new vesicles
exocytosis
vesicles fuse with cell membrane, expel contents
types of endocytosis
phagocytosis
pinocytosis
phagocytosis
cellular eating - solids
pinocytosis
cellular drinking - fluids
receptor mediated endocytosis;
ligands bind to specific receptor on cell surface
osmoregulation
control solute and water balance
contractile vacuole
eg. paramecium caudatum - freshwater protist
contractile vacuole
bilge pump, forces out fresh water as it enter by osmosis
