Post on 22-Dec-2015
AP Biology 2007-2008
Movement across the Cell Membrane
AP Biology
Diffusion ______________________________
governs biological systems universe tends towards disorder (entropy)
Diffusion movement from ___________concentration
Diffusion movement from ___________concentration
AP Biology
Diffusion Move from ______to _____concentration
“passive transport” no energy needed
diffusion osmosis
movement of water
AP Biology
Diffusion across cell membrane Cell membrane is the boundary between
inside & outside… separates cell from its environment
IN_________carbohydratessugars, proteinsamino acidslipidssalts, O2, H2O
OUT________ammoniasaltsCO2
H2O products
______________________________________________
IN
OUT
Can it be an impenetrable boundary? NO!
AP Biology
Diffusion through phospholipid bilayer What molecules can get through directly?
fats & other lipids Small polar molecules (H20)
inside cell
outside cell
lipid
salt
aa H2Osugar
NH3
What molecules can ________get through directly?
ions salts, ammonia
large molecules starches, proteins
AP Biology
Channels through cell membrane Membrane becomes ________________
with protein channels specific channels allow specific material
across cell membrane
inside cell
outside cell
sugaraaH2O
saltNH3
AP Biology
Facilitated Diffusion Diffusion through protein channels
channels move specific molecules across cell membrane
no energy neededopen channel = fast transport
facilitated = with help
_____
______
AP Biology
Active Transport Cells may need to move molecules ___________
concentration gradient shape change transports solute from
one side of membrane to other _________________ “costs” energy = _____ low
high
AP Biology
Getting through cell membrane ____________________
_______________________ diffusion of nonpolar, hydrophobic molecules
lipids high low concentration gradient
_____________________ diffusion of polar, hydrophilic molecules through a ____________________
high low concentration gradient
_______________________ diffusion __________________________
low high uses a _________________ requires _____
ATP
AP Biology
Transport summary
simplediffusion
facilitateddiffusion
activetransport
ATP
AP Biology
How about large molecules? Moving large molecules into & out of cell
through vesicles & vacuoles ______________
_____________________ = “cellular eating” _____________________ = “cellular drinking”
________________
exocytosis
AP Biology
Endocytosis
_________________
_________________
________________________________
fuse with lysosome for digestion
non-specificprocess
triggered bymolecular signal
AP Biology
Phagocytosis
AP Biology
Osmosis is diffusion of water Water is very important to life,
so we talk about water separately Diffusion of water from
__________________of water to __________________of water across a
semi-permeable membrane
AP Biology
Concentration of water Direction of osmosis is determined by
comparing total solute concentrations ___________ - more solute, less water
___________ - less solute, more water
___________ - equal solute, equal water
hypotonic hypertonic
water
_____ movement of water
AP Biology ___________ ___________ __________
Managing water balance Cell survival depends on balancing
water uptake & loss
AP Biology
Managing water balance Isotonic
animal cell immersed in ___________solution example:
________________________ problem: none
_________________of water flows across membrane
equally, in both directions
volume of cell is stable
balanced
AP Biology
Managing water balance Hypotonic
a cell in ____________ example: __________________ problem: __________________
swells & can burst water continually enters
Paramecium cell
solution: __________________ pumps water out of cell ATP
plant cells turgid
freshwater
ATP
AP Biology
Water regulation Contractile vacuole in Paramecium
ATP
AP Biology
Managing water balance Hypertonic
a cell in ________________ example: ________________ problem: _________________ solution: take up water or
pump out salt plant cells
________________ = wilt
saltwater
AP Biology
Cell (compared to beaker) hypertonic or hypotonic
Beaker (compared to cell) hypertonic or hypotonic
Which way does the water flow? in or out of cell
.05 M .03 M
Osmosis…
AP Biology
Any Questions??