PNB exam 2

membranes are responsible for creating blank by regulating the blank between blank blank

compartmentalization, transport, two compartments

fluid mosaic model

made up of two things which are : fluid and mosaic

define fluid

define mosaic

give an example of a fluid mosaic model

fluid, and mosaic

fluid: things can move within the plasma membrane or through it

mosaic: plasma membrane=made up of many diff biomolecules

double membrane surrounding our cells

also membranes surrounding Indiv organelles

what is the primary structural component of the plasma membrane

they have a blank blank among them

most of the plasma membrane is composed of

fat/lipids

enormous diversity

phospholipids(purple here)

like bread of sandwich

what are the two regions of phospholipids

the longer region is made up of blank blank, long chains of blank, their charge can be described as, therefore the tail is

the other region is made up of, they’re blank like molecules that contain a lot of, blank blank blank, and v blank blank group

the blank of blank in the blank groups of the blank causes the….

which makes it

a head and a tail

tails=fatty acids, hydrocarbons , relatively even distribution, non polar

heads=glycerol, sugar, hydroxyl side chains, phosphate functional group

electronegativity of oxygen, phosphate groups, head= uneven distribution of charge there making it polar

what does amphilic mean

this allows the polar head groups to interact with(2 things)

this is important bc there’s what kind of enviro inside and outside the cell(interstitial fluid)

what does it mean for the non polar tails , what is the name for this

due to phospholipids having hydrophilic heads and hydrophobic tails if you place a phospholipid in an aqueous enviro, it will

molecule with polar and non polar porperties

other polar molecules+water

important bc there’s an aqueous enviro

they want to avoid interacting with water, causes them to have forced interactions with themselves and other lipids-hydrophobic effect

spontaneously assemble into smth that resembles a membrane

the plasma membrane contains more than just phospholipids

describe the two other molecules

peripheral proteins: present only on one side of the membrance(intracellular or extracellular side)

integral membrane proteins: pass through the membrane on both sides

ex: channel proteins and carrier proteins

extra: most of the proteins willl be integral membrane proteins

the membrane creates a…, allowing for

the membrane is blank blank, meaning that it

a physical and chemical barrier around the cell, compartmentalization

selectively permeable,controls which molecules are able to move into and out of the cell

proteins associated with the plasma membrane can create…., allowing them to

this also contributes to how protein components of the plasma membrane can facilitate… between..

interactions between cells that, attach to each other

facilitate communication, cells

note: (plasma membrane is important for attachment)

the plasma membrane does NOT determine

the plasma membrane is primarily

plasma membrane is important for …

the structure, shape, or morphology of the cell

a chemical barrier,

regulating transport between 2 compartments

extra; not like bacterial cell wall

what are the 4 functions of the plasma membrane

physical barrier

exchange

communication

attachment

PM-regualting transport between 2 compartments

molecules can move in two ways, describe them

in the first one there is no…

second one is more what than the first one

between cells(paracellular transport), no selectivity of plasma membrane here

through cells(transcellular transport)-requiring molecules to cross 2 membranes, more selective than paracellular transport

phosphate(head) has negative charge meaning that the head

pulls/ attracts charges up towards the head of the phospholipid

in the non polar tail there are what kind of tails, how many

two kinked tails

define hydrophilic and hydrophobic

hydrophilic-water loving

hydrophobic-water fearing

the polar heads orient themselves towards what molecules

the tail groups orient away from what? bc they’re..

fluid inside the cell/interstitial fluid is made up of what moelcule

therefore what moelcule interacts with interstitial fluid and why

this allows for what

water molecules

water, hydrophobic

water

the polar heads to interact with intracellular fluid to protect the tails

selective permeability-most things are not able to pass directly through plasma membrane, create compartmentalization-kept out or kept in due to this structure

what are exceptions that can pas through membrane easily

oxygen and carbon dioxide-gasses

v small non polar gasses

lipid loving

extra: covid virus is small and in lipid can easily pass through plasma membrane

cholesterol too -lipophilic and small

what do helper proteins do

anything we have protein that passes all the way through the plasma membrane it is what , also..

integral proteins protrude into blank and blank blank

cell to cell peripheral recognition only interact with the outside and participate in cell to cell peripheral recognition most of the time, they are what kind of proteins

allow molecules to pass all the way through the lipid bilayer

an integral protien/integral membrane protien=ion channels

cytosol, extracellular fluid

peripheral proteins

what type of transport is simple diffusion, osmosis, and facilitated diffusion

bulk flow is what kind of transport, what does it dpeent on

simple diffusion and osmosis(diffusion of water), and facilitated diffusion= passive transport

bulk flow =based on pressure gradient, moving things down bulk flow

what does passive transport require

the bigger the gradient the more..

molecules move through what kind of movement

requires concentration gradient (high to low)

diffusion

random movement

time goes up exponentially faster in distance

what do we want to be able to transport really rapidly (molecule wise)

circulatory system, digestive system, renal system all depend on

gasses-oxygen and co2-want to be able to transport really rapidly

really small lipid molecule moles

on selectivity

we want to be picky abt what can enter or leave

determine which mols from external get into body or are released

everything else that’s not permeable like ions like sodium, potassium, small mols like glucose, etc move with help of what protein?

water transport requires the help of what?

everything else that’s not permeable like ions like sodium, potassium, small mols like glucose, etc move with help of integral membrane proteins

integral membrane proteins

classify transport across membrane in two ways

what does passive transport not require, what does it require

what does active transport require, is it independent or dependent on solute concentration?

passive transport-does not require energy/ATP

requires diff concentrations of molecules on both sides of the membrane

form high conc to low conc

active transport invest energy into transport, doesn’t need high vs low conc, can move mols independently of their concentration

simlple diffusion, osmosis, facilitated diffusion, and bulk filtration are alll what type of transport?

passive transport:

don’t require energy energy investment

diffusion is due to what? what is this known as

random walks-trajectory of molecule is…..

distance the molecule travels is not in equal proportion to

einstein figured out you can describe diffusion using what equation

the random movement of molecules-known as Brownian motion

non linear/moelcule doesn’t move in a straight line,

time it spends moving around

root mean squared equation: tells us that time and distance have a nonlinear relationship bc the distance a particle diffused increases as the square root of time

when our molecules move randomly, they move left, right-x plane and forwards backwards in y plane and up and down in z plane

in each of these dimensions, what happens to diffusion

is diffusion efficient or inefficient going a long distance

when our molecules move randomly, they move left, right-x plane and forwards backwards in y plane and up and down in z plane

it gets less and less efficient with respect to time

important: rly inefficient to move a long distance using diffusion

describe the rate of diffusion over a long distance and over a short distance

when temperature increases, what happens tothe rate of diffusion

diffusion happens where,

diffusion=passive

slow over a large distance but extremely fast in a short distance

diffusion rate increases

diffusion happens everywhere, in open system or inside cellular compartment, or across divider/partition like plasma membrane

when molecules are larger, what happens to the diffusion rate

what does diffusion require

what is a concentration gradient

decreases

requires a concentration gradient

concentration gradient=absolute difference in solute concentration between two places, calculable

suppose you have two compartments, the left side has 10 red solute molecules and the right has 0 red solute molecules, what is the concentration gradient/difference in concentration

suppose this time, the two compartments both have five molecules in each side, what is the concentration gradient

what is flux

concentration gradient/difference in concentration of ten

0 here bc equal Amt on each side

flux: describes the movement of a particle in a single direction

what is net flux

if you have the same number of molecules moving left and right, what is the net flux , what is the other word for this

the overall pattern of movement in the population(after adding up flux from every molecule moving at the exact same time) =net flux

=0 , also equilibrium

extra: flux=vector too

bc mols is moving randomly, there’s flux one very possible direction(left , right, up , down,e tc)

describes each step in Brownian motion,

teh rate of diffusive flux is equal to what

the primary determinant for us is usually …

that molecules diffusion coefficient times it’s concentration gradient

concentration gradient

extra: diffusion coefficients=always constants and unique for every molecule

to find the difference in concentration gradient from one side vs the other, how do you do that?

subtract the side with least solute from the one with more solute

membrane surface area, membrane thickness, and concentration gradient are related to what?

composition of lipid bilayer, lipid solubility, and molecule size are related to what

in order for a mol to move across membrane pasively, it has to first be blank then

pink=related to diffusion

blue boxes= terms related to permeability

permeable and then diffuse

EXTRA

structure function relationships

structures inside of body that need to maximize rte of transport using diffusion, they opitmize their parameters, ex lungs

structure function relationships

structures inside of body that need to maximize rte of transport using diffusion, they opitmize their parameters, ex lungs

highly vascular/lot of blood flow , having vascularity increase surface area

small intestine: has villas and valleys called vili, increases membrane surface area

define osmosis

mass displaces what

what do solutes do to the concentration of water

if there is a high concentration of solutes, there will be what concentration of water

osmosis: diffusion of water molecules

volume

solutes lower the concentration of water so a compartment with higher concentration of solutes has a lower concentration of water,

extra: don’t find pure water anywhere in the body, always has solutes dissolved within it

what will the result be (note the barrier is semi permeable to water)

what will happen to the volume of water on each side and why

in tube:

water moves from left side of tube to right side of tube

causes left side to decrease in volume and right side to increase in volume(direct relationship)

(separated by a membrane freely permeable to water and solutes)

what will happen here

what will be the result solute and water here

what is the net flux

bc membrane is freely permeable to both, both can move down their conc gradient until conc gradient no longer exists

result: equal concentrations of solute and water on both side, net flux is 0 here, containers have equal solute

selectievely permeable membrane, only permeable to water

what will happen here

what will happen to the volume on both sides

what is movement of water linked to , it happens when

solute concentration in right side is higher 4 vs 2

bc there’s a conc gradient for water it moves from high conc to lower conc. move from left to right

left chamber loose volume, right side gains volume all from water.

changes in cell volume

solutes are unevenly distributed between two compartments

extra: we don’t typically want cells to change volumes so we have to regulate solute concentrations v carefully to limit what type of transport

osmosis that occurs

what is tonicity , what does it describe

what is a hypertonic solution

the relationship between volume and solute concentration

describing the conc of outside enviro relative tot he inside enviro

more solute outside the cell than inside the cell(high solute and less water)

extra: relative term that always reuiqre comparison between wo compartments

what is the result of cells being in a hypertonic solution

causes water to move out of the cell into the extracellular fluid and loose volume

what is a hypotonic solution

what is the result of cells being in a hypotonic solution

the plasma membrane does not give

lower solute outside the solution(and more water) outside the cell than inside the cell.

water comes inside the cell, cell increases in volume and swells, looses structural integrity

give physical protection

solute concentrations must be blank for cells to stay the same size

what is isotonic

balanced

when the extracellular solute concentration=to intracellular solute concentration

if we’re experiencing osmotic forces-pressure created by the water, it’s balanced out by some counterbalancing force

what is the hydrostatic force

the counterbalancing force, force that’s created by a fluid kept under pressure

facilitated diffusion

it requires the help of what molecule

give an example

an integral membrane protein for a molecule to be soluble

ex glucose transporters(help to bring glucose into he cell following a meal

glucose is large can’t pass through the membrane, requires the help of a carrier protein

bulk flow is what type of transport

what does it not require

instead it depends on what

as this gradient moves. from high to low, what moves with it

passive transport process

NO concentration gradient-moves mols independently of their concentrations

a pressure gradient,

as pressure equalizes(moves form high pressure to low pressure) the solutes are carried along with it

facilitated transport also uses ion channels, which is an example of what

with integral membrane proteins, each piece of the protein comes together to form a…

-specific type of integral membrane protein(that’s channel mediated)

integral membrane protein:

pore(tunnel) through the plasma membrane

which aspects increase the rate of flux and are proportional, which decrease the rate of flux and are inversely proportional

membrane thickness, lipophilicity, temperature, molecule size, surface area, and concentration gradient

increases the rate of flux and are proportional: temperature, surface area(bigger door instead of smaller door for molecules to pass through) , lipophilicity, concentration gradient

decrease rate of flux and are inversely proportional: membrane thickness and molecule size

with ion channels, is the pore opened all the time , what odes each ion channel always have

what Is a gating mechanism

what are voltage gated Chanels

what are mechanically gated ion channels

regardless of how it’s opened or closed, when door is open, how many molecules come in per second

no, each ion channel has a gate or a door

diff ways that you can open the gate/door

when channels opened based onchanges in charge of enviro outside of plasma membrane

ion channels that open based on changes in the physical structure of the cell

a lot

ion channels are what kind of transport

gating mechanisms are blank specificity

ion channels usually contribute to what?

what’s channelopathy

=always passive

complex gating mechanisms-high specificity

diseases,

disease that are caused by mutations in genes that encode the ion Channels(happens often)

FUGU-poisonous fish

can die from eating the fish caused by tetrodotoxin

what is tetrodotoxin

-toxin that evolves v specifically to inhibit voltage gated sodium channels

extra: they took that knowledge of that drug to develop new pharmaceutical drugs and study voltage gated channels

different mechanisms can be blank

channels form a pore OR blank blank across membrane

interdependent

continuous path across membrane

not all integral proteins=channels, some can be carriers/ transporters

carriers operate by alternating access model-never a continuous path throughout plasma membrane

carrier undergoes a conformational change that opens up to one membrane face and allows the solutes that are in that compartment to bind to the carrier

then it closes so it’s not accessible to the inside or the outside, trapping the solute inside=Occulusion state

then opens it up the opposite side to allow the solute to unbind and get released into the opposite compartment

other difference between carriers and channels

solutes have to actually bind to transporters to occur

NO binding in ion channels

transporters have a limited number of binding sites, carriers only move 1-5 mols per cycle

channel moves tens of thousand molecules per second

having binding sites can limit the rate of transport

concentration of solute on x axis

as concentration of solute increases, rate of transport also increases

but eventually the rat elf transport plateaus

direct consequence of having a limited number of binding sites

DOESN”T HAPPEN WITH CHANNELS

carriers tend to be larger than ion channels0prob due to the conformational channels that they have to make that ion channels don’t (open or close)

carriers can be classified bassedupone th number of solutes that they transport and the direction that they transport them

a carrier that transports only a single solute=uniport

more than 1 solute and f both solutes are being transported in the same direction=symport carrier

if the solutes are traveling in opposite directions=anti port carrier

primary carriers: carriers that don’t use energy work via facilitated diffusion

carriers that do require erg for transport can be either primary or secondary active transporters

primary active transportes; contains an enzymatic domain that hydrolyzes and breaks down ATP , most here are either uniporters or anti porters

secondary active transporters: use energy stored in pre-existing electrochemical gradients, most are symporters

sodium potasium pumps

sodium=highly concentrated outside the cell

potassium is highly concentrated inside the cell

sodium potassium cells move 3 mols of sodium out and 2 mols of potassium into the cell

both mols are moving in diff directions= S potasium pump=antiporter

bc both mols=moving against concentration gradients requires ATP

sodium potassium pump contains an enzymatic domain that breaks down ATP giving it the energy needed to do this transport

primary active transporter

sodium potassium pump can be plugged into alternating access model (open, closed, open)

sodum gl

sodium glucose transporter transports sodium and glucose into the cell

bringing sodium into cell is moving down concentration gradient, allows transporter to use energetic favorability to use glucose into cell, even though its unfavorable

by the coupling of these two, you et sodium glucose transporter that works via secondary active transporter

uses ALTERNATING ACCESS MODEL (open, closes, opens to opposite side)

passive and active transport can work together

epithelial cell in your gut does glucose absorption

on basal lateral membrane=sodium potassium pump(pumps potassium ina nd sodium out)

keeps sodium conc inside the cell v low

apical /topmembrane: sodium glucose supporter there(uses conc gradient of sodium to transport glucose in too) , increase glucose inside the cell to be absorbed into

allows glucose to be absorbed into intestinal fluid through facilitated diffusion

active transport helps to set and maintain the conc gradient that the passive transporters require to work