Whats the plasma membrane composed mainly of?
Phospholipids
the principal components of the plasma membrane?
lipids(phospholipids, and cholesterol), proteins, carbohydrates
what is NOT a cell membrane component?
Nucleic acids
what region of the cell membrane are hydrophobic?
the tails facing the interior
What region of the cell membrane is hydrophilic?
the head group which interacts with water
Membrane has hydrophobic or hydrophilic core?
Has hydrophobic core
what is imbedded in the membrane?
proteins, throughout the membrane
what carbohydrates are attached to lipids?
glycolipids
what are carbohydrates that are attached to proteins?
glycoprotein
Cholesterol exists where in the membrane?
embedded in hydrophobic core of the membrane
Fluid mosaic model
model of the membrane.
membrane is considered mosaic of?
lipids, phospholipids in cholesterol, proteins and carbohydrates.
why is mosaic fluid
its a fluid because it is not rigid, it is between solid, and liquid.
lipids can move relative to eachother
what are proteins in the membrane?
integral proteins, lipid anchored proteins, peripheral proteins
integral proteins
referred to as transmembrane protein, they span the entire membrane
lipid anchored proteins
covalently bonded to the phospholipids, an amino acid side chain in the membrane
peripheral protein
non-covalently bound to integral proteins. weak bond, can pop on and off membrane easily
why is the membrane fluid?
molecules can move in the membrane. they can spin in their axis, they can go in circles where they are, moving laterally in their membrane leaflet
what is a Membrane leaflet?
one side of the membrane
what can molecules NOT do in their leaflet?
move from 1 leaflet to another leaflet because the tails are hydrophobic and the head is hydrophilic.
whats the ONLY exception to molecules moving from leaflet to leaflet?
if their is a special protein, an enzyme called flippace, and you'll need ATP
flippace
an enzyme(proteins) embedded in the phospholipids bilayer that requires ATP to transport lipids from leaflet to leaflet
fluidity means
individual molecules remain in
close association yet have the
ability to readily move within the membrane
semifluid
most lipids can rotate freely
around their long axes and move
laterally
within the membrane leaflet
what are 3 factors affecting fluidity?
Length of fatty acid tails, presence of double bonds in fatty acid tail(acyl acid), and presence of cholesterol
factor affecting fluidity,
length of fatty acid tails
shorter tails mean more fluidity, they,re less likely to interact than if they were long tails, which makes the membrane more fluid.
factor affecting fluidity?
presence of double bonds in fatty acid tails
double bonds kink in fatty acid tails. making in more difficult for neighboring tails to interact and make the bilayer more fluid
factors affecting fluidity?
presence of cholesterol
cholesterol decreases the fluidity of the membrane, and stabilizes the membrane
cholesterol
4 interconnected carbon rings
what it means when proteins are anchored to cytoskeloton?
that they can NOT move
can lipids move in the membrane in all cellular ways?
Yes! they just CAN NOT flip
Selectively permeable
prevents certain molecules from getting in and getting out of the cell
selectively permeable structure ensures..
essential molecules enter, metabolic intermediates remain, and waste products exit
Diffusion
net movement of a solute from a region of high [ ] to low [ ]. does NOT require energy, is Passive.
example of diffusion
perfume, people on a bus
is diffusion passive?
Yes. it does not require any additional energy input from the cell. Cell doesn't have to expend any energy for diffusion to happen.
passive diffusion
Diffusion of a solute
through a membrane without transport protein
does the cell have to expend any energy for diffusion to take place?
NO
movement by thermal energy
high concentrated molecules are bouncing off of each other eventually into the open space randomly
brownian motion
random bouncing
what type of environment promotes molecules to move around fast and bounce around? and what happens with diffusion?
on hot plates molecules move/bounce around fast, increasing the rate of diffusion
what type of environment do molecules move around slowly, and what happens with diffusion?
in a freezer molecules will move slower, decreasing the rate of diffusion
phospholipid bilayer barrier
A barrier to molecules/ions that is hydrophilic due to hydrophobic interior.
what is a cell membrane impermeable to?
any polar charged molecules. only maybe a few glasses and water can directly diffuse through the membrane
what are the small glasses that can easily diffuse through the membrane?
O2, CO2, N2, CO
A gradient
the DIFFERENCE in concentration from 1 side of the membrane to another
a cell maintains gradients.
is equilibrium the goal for cells?
No, maintaining equilibrium is not the goal for cells
which of the following can diffuse through the membrane?
O2, glucose K+, amino acids
O2. glucose, K+, and amino acids are too big, and too polar, they diffuse slowely
concentration in a membrane
if one side of the membrane is high concentration, the other side is low concentration
osmosis
diffusion of free water toward higher concentrations through a selectively permeable membrane
what happens if solute's cannot move?
the movement of water will cause cell to swell when the water moves in, or shrink when water moves out
Tonicity
isotonic, hypertonic, hypotonic solutions
isotonic
Equal water and solute concentrations on either side of the membrane
hypertonic
Solute concentration is higher outside the cell (and water concentration lower)
hypotonic
Solute concentration is lower outside the cell (and water concentration higher)
Crenation
when cell shrivels due to water leaving the cell
(hypertonic solutions)
plasmolysis
when the cell membrane pulls away from the cell wall due to lack of turgor pressure
turgor pressure
pressure exerted onto the plasma membrane by the vacuole
force within the cell pushing the plasma membrane against the cell wall
aquaporin
transmembrane proteins that allow the passage of water much faster and efficiently through the membrane. water will flow toward the higher solution no matter which side its on
osmosis and diffusion
are passive processes they DO NOT require additional energy from the cell. energy comes from thermal energy
osmotic pressure
the tendency for water
to move into any cell
which of the following requires energy from the cell?
osmosis, active transport, diffusion, facilitated diffusion
active transport
active transport
REQUIRES energy from the cell to move solutes from low concentration to high concentration (against concentration gradient) energy required is usually in form of ATP. Also require a protein.
what is falicitated diffusion
the diffusion of a solute from high to low [ ]. diffusion is passive. DOES require a membrane protein to transport the molecules. proteins are specific to molecules they transport
facilitated diffusion of glucose
large molecule, cant diffuse through membrane itself, trans-membrane facilitating proteins helps
the DIFFERENCE between simple diffusion, and facilitated diffusion?
facilitated diffusion required a membrane protein to transport the molecule
under what condition would facilitated diffusion move a solute from the cell?
in a hypotonic condition
transport proteins // channel proteins
they don't change shape as solutes pass.
ligated channel, gated channel
ligated channel
is closed until a molecule binds to it, causing channel to open
gated channel
is closed until polarity of membrane changes.
carrier proteins
change shape as the solute passes
Uni-porters, symporters, antiporters
uniporters
single molecule or ion.
moves 1 solute for example (glut 1)
symporter/cotransporter
2 or more ions or molecules transported in same direction
antiporter
move 2 or more solute in opposite directions for ex. The Na+/K+ pump.
major limitation of simple/facilitated diffusion
them Going down the concentration gradient the opposite of the definition
cotransport
active transport of substance indirectly drives transport of other substances
downhill(energy release)
cell does nothing. Diffusion is downhill because it doesn't need energy.
uphill(requires energy)
this is an Active transport bc it requires energy to happen
are Exo/Endocytosis nonspecific?
yes
exocytosis
is bulk transport of solutes out of the cell.
endocytosis
is the bulk transport of molecules or solutes into the cell. Pinocytosis- the bulk uptake of liquid material containing dissolved solutes
phagocytosis
the bulk uptake of solid material. The vesicle with engulfed solid
be it a yeast or bacteria fusses with a lysosome to be degraded
tight junctions
so tightly attached that nothing can get between the cells. Proteins are attaching cells together.
gap junction
Communication junctions, passageways between cells allowing material to pass between them. Like a tunnel from one cell to the other able to pass material between cells.
anchoring junctions
they hold cells together like a bolt or staple. Material can get in between cells but they're still attached.