membrane and permeability
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what is the main function of the plasma membrane
defines the outer border of the cell
what does the plasma membrane control
what enters and leaves the cell
how does the plasma membrane receive external signals
membrane proteins receive signals and trigger cell responses
how does the plasma membrane help neighboring cells
helps cell stick/attach to each other
what is cell recognition
cells identifying and distinguishing one another wha
what are the 3 major molecule groups in the membrane
phospholipids + cholesterol
proteins
carbohydrates
what do phospholipids + cholesterol mainly provide
the basic structure of the membrane
what are membrane proteins involved in
transport, signaling, and other membrane functions w
what is an important role of membrane carbohydrates
helping cells recognize each other
what are the 5 main plasma membrane functions
boundary
entry/exit
signaling
adhesion
recognition
what does fluid mean in fluid mosaic model
the membrane is flexible and its molecules can move
what does mosaic mean in fluid mosaic model
the membrane contains many different types of molecules
what is a phospholipid bilayer
2 layers of phospholipids forming the membrane
what provides flexibility and fluidity to the membrane
the lipid portion, especially phospholipids
what determines most of the membranes specific functions
membrane proteins
what is fluid-mosaic model
a flexible membrane with different models embedded in it
what is the main structure of the plasma membrane
a phospholipid bilayer
what are membranes primarily made of
phospholipids
what does amphipathic mean
having both hydrophilic and hydrophobic part
what are phospholipid tails made of
fatty acids
what is a saturated fatty acid
fatty acid with no double bond
how do saturated acid tails pack
tightly
what is an unsaturated fatty acid
a fatty acid with one or more double bonds
how do saturated fatty acids tails pack
loosely because of bends/kinks
which type of tail makes a membrane more fluid
unsaturated fatty acid tails
what does the plasma membrane separate
the watery inside of the cell from the watery outside
what is selective permeability
the membrane allows some substances to pass through but restricts others
why is selective permeability important
it helps control what enters and leaves the cell
what is membrane fluidity
how easily molecules move within the membrane
what happens when membrane fluidity with unsaturated fatty acid tails
fluidity increases.
why do unsaturated fatty acid tails increase fluidity
their bends/kinks prevent tight packing
what happens to the membrane fluidity with saturated fatty acid tails
fluidity decreases
why do saturated fatty tails decrease fluidity
they are straight and pack tightly
what happens to membrane fluidity in cold temperatures
fluidity decreases.
what happens to membrane fluidity in warm temperatures
fluidity increases from warm temps.
what is cholesterols role in the membrane
acts as fluidity buffer
what does cholesterol do in cold temperatures
prevents membrane from becoming too rigid
What does cholesterol do at warm temperatures
prevents membrane from becoming too liquid
what is the second major component of the plasma membrane
proteins
what do membrane transporters do
help move substances across the membrane
what do membrane enzymes do
speed up chemical reactions
what is the structural role of a membrane proteins
attach the membrane to structures inside the cell
what do recognition sites on membrane proteins do
help cells recognize signals or other cells
what are the 4 main functions of membrane proteins
transport
enzymes
structural attachment'
recognition
what are integral proteins
proteins embedded in the phospholipid bilayer
where are the hydrophobic regions of integral proteins
within the membranes hydrophobic interior w
what is a transmembrane protein
an integral protein that spans the entire membrane
what is the difference between integral and transmembrane proteins
transmembrane proteins cross the entire membrane
integral proteins are embedded in it
what are peripheral proteins
proteins attached to the membranes surface
what are peripheral proteins
proteins loosely attached to the surface of the membrane
where are peripheral proteins located
on the interior or exterior surface of the membrane
do peripheral proteins penetrate the membranes hydrophobic interior
no
what can peripheral proteins attach to
integral proteins or phospholipids
what is the main difference between integral and peripheral proteins
integral proteins are embedded
peripheral proteins are on the surface
where are membrane carbohydrates located
on the exterior surface of the cell membrane
what is main function of membrane carbohydrates
cell-cell recognition
what is a glycolipid
carbohydrate attached to a lipid
what is a glycoprotein
a carbohydrate attached to a protein
what is the glycocalyx
the carbohydrate-rich layer on the outside of the surface
what do membrane carbohydrates act like for cells
ID tags that help cells recognize each other
what does it mean that the plasma membrane is asymmetrical
the inner and outer surfaces have different molecules and functions
why is the plasma membrane asymmetrical
the inside and outside face different environments
where are glycoproteins found
outer surface of the membrane
what is one function of glycoproteins on the outer surface
cell recognition
what can some interior membrane proteins connect to
cytoskeleton
what does selectively permeable mean
allows some substances through while preventing others
why is selective permeability important
it allows the cell to control what enters and leaves
what is the cytosol
fluid inside cell
what is extracellular fluid
fluid outside of cell
what type of molecules can cross the lipid bilayer easily?
small, nonpolar molecules
why can small nonpolar molecules cross easily
they can dissolve in the membranes hydrophobic interior
do polar molecules cross the lipid bilayer easily
no, they cross poorly or not at all
why dont polar molecules cross easily
membranes interior is hydrophobic
can ions cross lipid bilayer on their own
no
why cant ions cross the lipid bilayer
they are charged and cannot pass through the hydrophobic interior