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Chapter 7: Membrane Structure & Function - Coggle Diagram
Chapter 7: Membrane Structure & Function
Membranes in Selective Permeability
lipid bilayer
pass through easily:
small
nonpolar (hydrophobic)
uncharged
do
not
pass through easily:
charged
polar (hydrophilic)
large
transport proteins
hydrophilic substances cross membrane more rapidly
channel proteins
certain molecules/ ions use as tunnel
carrier proteins
bind to molecules & change shape → shuttle across membrane
Passive Transport
moving
down
the concentration gradient
does
not
require energy
diffusion
movement of
particles
from high to low solute concentration
concentration gradient
divides high and low concentration of solute (not always visible)
facilitated diffusion
usually carrier proteins (carry molecules across cellular membrane)
help from various proteins
transport proteins (specific)
channel proteins (tunnel)
aquaporins
allows water molecules to pass through
ion channels (move ions across)
gated channels (open/close: response to stimuli)
carrier proteins (change shape)
osmosis :droplet:
movement of
water
through a semipermeable membrane from low to high solute concentration
water follows higher concentration of solute
tonicity (measure of osmosis)
hypo
tonic (less)
hypotonic
solution
animal cell:
lysed
/ bursts
plant cell:
turgid
/ firm (normal)
hyper
tonic (more)
hypertonic
solution
animal cell:
crenate
/ shriveled
plant cell:
plasmolyzed
/ shrivels & membrane pulls away
iso
tonic (same)
isotonic
solution
animal cell:
normal
plant cell:
flaccid
/ limp
osmoregulation
control of solute concentration & water balance
Active Transport
moving
against
the concentration gradient
requires energy (ATP)
movement of
molecules
from low to high concentration
transport proteins (specific)
carrier proteins
sodium-potassium pump (animals)
K+ in
Na+ out
3 Na per 2 K
crucial for heart/muscles
ion pumps
membrane potential
voltage across a membrane
allow muscle contraction
voltage
difference in distribution of + & - ions across a membrane
proton pump (plants, fungi, bacteria)
transports H+ out of the cell
cotransport/ symport
active transport of solute indirectly drives transport of other
(SGLT in digestive system)
Bulk transport
endo
cytosis (inside)
takes substances
into
the cell
phagocytosis (cell eating: solids)
pinocytosis (cell drinking: fluids)
receptor-mediated cytosis
vesicle formation triggered (solute binding to receptors)
shrinks cell (membrane forms pocket/ pinches off)
exo
cytosis (outside)
enlarges cell (vesicle fuses w/ membrane)
substances exit the cell
Cellular Membranes are Fluid Mosaics
fluidity of membranes
proteins
purposely distributed (determine function)
clustered in groups (all different)
resembles tile mosaic
2 main types
peripheral (surface)
integral (penetrate hydrophobic core)
transmembrane (spans membrane)
carbohydrates (in cell membrane)
cell to cell recognition (by geometric shape)
cell identifiers
glycolipids (carbohydrates bonded to lipids)
glycoproteins (carbohydrates bonded to proteins)
lipids
phopholipids
amphipathic (hydrophilic & hydrophobic)
phosphate (hydrophilic head)
fatty acid (hydrophobic tails)
unsaturated (double bonds: more fluid)
saturated
differences in membrane comp
changes in response to temp
adapted to environmental conditions
must be fluid to work properly (unsaturated fatty acids/ cholesterol)
too fluid = cant support protein structure