Cell Membrane Flashcards
how permeable is the cell membrane?
semi/selectively permeable
allows some things in and some things out of the cell
how are the heads and tails in the cell membrane? what is this called?
hydrophobic tails
hydrophilic heads
amphipathic
what is the early model of the cell membrane?
sandwich membrane:
protein
hydrophilic zone
hydrophobic zone
hydrophilic zone
what is the current and accurate cell membrane model?
fluid mosaic model
not rigid
hydrophilic region of protein
phospholipid bilayer
hydrophobic region of protein
what components of the cell membrane are in a mosaic pattern?
proteins float randomly in the PLBL
what does the fluid property of the cell membrane allow for?
allows the phospholipid to move easily in a lateral direction
the phospholipids can also sometimes flipflop across the membrane
what gives the cell membrane more fluidity?
the unsaturated/polyunsaturated hydrocarbon tails that have double bonds
what do the saturated hydrocarbon tails do to the cell membrane?
make it more rigid
at room temp, what does adding cholesterol to the cell membrane to it?
lowers fluidity, more rigid
what happens if you add cholesterol to the cell membrane at low temp?
increases fluidity, prevents phospholipids from clumping
what does the versatility of cholesterol at diff temp allow? ex?
allows animals that live in very cold climates to still maintain plasma membrane function
hooves of animals have a lot of cholesterol to prevent freezing when exposed to snow
components of the cell membrane (10)
- ECM/Glycocalyx
- Integral Protein: Transport Protein
- Integral Protein: Integrin Protein
- Integral Protein: Aquaporin
- Cholesterol
- Peripheral Protein
- Cytoplasm and Cytosol
- Phospholipids
- Glycoprotein
- Glycolipid
where are integral proteins located?
span across the phospholipid bilayer
structure of integral proteins
alpha helixes (secondary structure)
what do transport proteins do?
allow specific molecules to enter or exit the cell
what do integrins do?
used for cell communication
where are peripheral proteins found?
usually found on the inside ofthe cell membrane
peripheral protein function
give strength to cell
what bring the selectively permeable nature to the membrane?
hydrophobic/nonpolar tails
what molecules would not be able to get pass the nonpolar tails?
ionic/charged molecules, most polar molecules, large molecules
what molecules would easily get past the nonpolar tails?
nonpolar, small, gases, steroids
what will the molecules that cannot get past the cell membrane use?
use specific transport proteins that have a charged interior
what does water use to enter and exit the cell membrane?
transport protein called aquaporin
what is diffusion?
tendency for molecules to spread out in an open space
diffuse from a high to low concentration
spontaneous and require no ATP
passive transport
what is osmosis?
passive transport of water from high to low concentration across a semi permeable membrane
hypertonic solutions
high concentration of solutes in solution
hypotonic solution
low concentration of solutes in solution
isotonic solution
same concentration of solutes on both sides
what way does water always move? what if it’s isotonic?
hypotonic to hypertonic
water still continues to move between the two solutions at equal rate
if an animal cell is placed in a hypotonic solution, the cell will?
lyse
if an animal cell is placed in an isotonic solution, the cell will?
stable
if an animal cell is placed in a hypertonic solution, the cell will?
shrivel
if a plant cell is placed in a hypotonic solution, the cell will?
turgid/ rigid
if a plant cell is placed in an isotonic solution, the cell will?
flaccid (limp)
if a plant cell is placed in a hypertonic solution, the cell will?
plasmolysis - cell membrane pulls away from cell wall
which solution do terrestrial animal cells want?
isotonic
which solution do terrestrial plant cells wanr?
hypotonic
many terrestrial animal cells are in what type of solution?
isotonic
what type of solution are protists in?
hypotonic environments and must osmoregulate
what is osmoregulation? how do protists do it?
control their water by balance with the help of contractile vacuoles
why do plant cells respond differently than animal cells in a solution?
cell wall
what is facilitated diffusion?
passive transport of a substance across the cell membrane from a high to low concentration, but requires a transport protein
what is active transport?
require ATP as it goes from low to high concentration
uphill reaction that goes against the concentration gradient
good example of active transport?
Na-K
how many and in which direction are the sodiums and postassiums going?
3 Na+ out, 2 K+ in
what is a membrane potential/electrochemical gradient?
idea that all cells have voltage on each side of the plasma membrane
charge of inside of cell? outside
inside - negative
outside - posotive
what does the differing charges of the cell interior and exterior do?
favors cations to come into a cell and anions to exit the cell
what are animals main pump? plants?
animal - Na-K pump
plant - proton pump
what do proton pumps do?
actively pump H+ ions out of cells from a low to high concentration
potential energy from what can be used to transport other substances across the membrane?
energy generated by transmembrane solute gradients can be harvested by the cell
a substance that is actively transported across a membrane can do work as it diffused back by facilitated diffusion
what is cotransport ex?
a plant cell actively pumps H+ out of a cell
H+ then leaks back into cell passively by facilitated diffusion through a transport protein
brings back with it small sugars, amino acids, or nutrients
how do large molecules enter or exit a cell? is this active or passive transport?
endo/exocytosis; active
large molecule entering cell
endocytosis
large molecule existing cell
exocytosis
cell takes in food
phagocytosis
cell takes in fluid
pinocytosis
receptor-mediated endocytosis
very specific
proteins on the outside of a cell bind to a specific molecule
general term for any molecule (usually small) that binds to something (other a receptor)
ligand
what does receptor- mediated endocytosis allow?
allows a cell to take in more substances that in normally would, even if the substance in is low concentrations outside the cell
ex of receptor-mediated endocytosis
cholesterol is acquired by cells this way
how can transport proteins respond to change in the extracellular environment? ex
with active transport
if a cell has enough Na+, a transport protein can slow/shut down the active pumping of the molecule up the concentration gradient
what does not depend on if the cell has enough of a substance unlike transport proteins?
diffusion
passive transport