Module Part 4 Cell Membrane

Question 1

Function of the Cell Membrane (3)

Answer 1

Separates components from environment

Gatekeeper, selectively permeable

Maintains homeostasis

Question 2

For homeostasis to be maintained you need to balance (4)

Answer 2

pH
temperature
glucose
water balance

Question 3

Homeostasis:

When a pH solution is unbalanced, you need a ____

Answer 3

BUFFER

Question 4

Cell membrane is made up of ___, ___, and ___ which is why its called a phospholipid bilayer

The bilayer is only made up of ___ and ___

However, the specific parts once formed include the ___, ___, and ___

Answer 4

Phosphate
Proteins
Lipids

Phosphates and Fats

Lipid Bilayer
Protein Channel
Protein Pump

Question 5

Does not require energy to move molecules from a HIGH water conc to LOW water concentration

Requires energy (ATP) to move molecules from a LOW water conc to HIGH water concentration

Answer 5

Passive Transport

Active Transport

Question 6

Passive Transport kinds (3):

____ Movement of small particles across the cell membrane until homeostasis is reached. Sometimes, Molecules spread out into a more free environment, tightly packed if in high conc

____ Like (1) but ___ and ___ proteins aid in pushing the molecules across

___, the movement of WATER through a selectively permeable membrane. HIGH WATER to LOW WATER

Answer 6

Diffusion

Facilitated Diffusion, Carrier Proteins, Channel Proteins

Osmosis

Question 7

Osmosis:

____ Solutions have high concentration of solute, causing it to make a cell____. Water diffuses ___

____Solutions have low concentration of solute, causing it to make a cell ___. Water diffuses ____

____ Solutions Same concentration. Water diffuses ___

Answer 7

Hypertonic, Shrivel, out

Hypotonic, Swell, In

Isotonic, Into and Out

Question 8

Active Transport types (4)

Materials EXIT the cell

Materials ENTER the cell

SMALL Materials ENTER the cell

LARGE materials ENTER the cell

Answer 8

Exocytosis

Endocytosis

Pinocytosis

Phagocytosis

Question 9

Proteins involved in active transport are known as ____

Blood vessels are ____ in carbon dioxide compared to the cells so energy is used to pull the carbon dioxide from LOW SOLUTE concentration to HIGHER SOLUTE CONCENTRATION so the carbon dioxide can go with the blood vessels

Answer 9

Protein pumps

High

Question 10

a distribution of charge across
the cell membrane

A. The body as a whole is electrically ___

B. All fo the cells of the body have an electrical potential across their membrane, a ____

C. Membrane potentials develop because of ____ between the inside and outside of the cell

Answer 10

Membrane potential

Neutral

Voltage Difference

Differing Ion Concentrations

Question 11

Membrane potential:

Commonly reported resting membrane volt value of cells

Is in unit of ___

____ is always measured between two points

Answer 11

-70 mV

Millivolts

Voltage

Question 12

Membrane potential:

____ Flow of electrical charges from one point to another

1. ___ charges repel ____ attract
2. Ions tend to move from areas of ____ to areas of ____
3. Movement of a ____ ion from one side of a membrane to the other implies a ____ charge is left behind

Answer 12

Current

like, unlike

greater concentration, least concentration

positive, negative

Question 13

Membrane potential:

____the voltage across a conductor is directly proportional to the current flowing through it, provided all physical conditions and temperature, remain constant

I=
E=
R=

Subsequent equation:

Answer 13

Ohm’s law

Current Flow
Electrical potential
Resistance

(I=E/R)

Question 14

Membrane potential:

____ = Aqueous solution + good conductor

____ = A few charged groups can not carry current - high electrical resistasnce - good insulator

___ and ___ - both have low electrical resistance

Answer 14

Cell

Lipid Membrane

Extracellular Fluid, Intracellular Fluid

Question 15

____ Describes the steady state of the cell

BY convention the ECF is assigned a voltage of ___

____ of the membrane is stated in terms of excess charge ____ the cell

Answer 15

Resting Membrane Potential

Zero

Polarity
Inside

Question 16

Membrane Ion Channels:

___Open all of the time, slow passage of ions, permeability is constant (neurons). Random opening

a. ___,____ & ___

b. Biased towards ____ because it is 75% more permeable to it

c. Accounts for ___ of the resting membrane potential

Answer 16

Leak channels

Sodium, Potassium & Chlorine

K+

95%

Question 17

Membrane Ion Channels:

____ Unequal transport of POSITIVE IONS makes the ICF more ____ than it would be just from diffusion alone

It is an ____ pump

___Na+ : ___ K+ (NOTE Na+ IN K+ OUT)

Answer 17

Na+K+ATPase Pump

Negative

Electrogenic

3:2

Question 18

Types of Channels (4)

Always Open (Exterior has the normal positive charge and cytosol has negative) Restign potential

Opens (transiently) in response to CHANGE in the membrane potential (Exterior in this case is negative)

Opens & Closes in response to an EXTRA cellular neurotransmitter

Open & Closes in response to a specific INTRAcellular molecule

Answer 18

Resting K+ Channel — K+

Voltage-gated Channel — Na+

Ligand-gated Channel — Na+

Signal-gated Channel — Na+

Question 19

Membrane Channels:

Voltage-gated channels are responsible for propagating action potentials along the ____ membrane

While, Ligand-gated and Signal-gated channels found in ____ and ___ are responsible for generating ____ in ____

Answer 19

Axonal Membrane

Dendrites and Cell Bodies

Electric Signals in Postsynaptic Cells

Question 20

Membrane Potential:

Too much K+ in the blood

Answer 20

Hyperkalemia

Question 21

Membrane Potentials Ion Gradients:

Generally called a ____

Two Forms include ____ and ____

Answer 21

Electrochemical Gradient

Chemical Concentration Gradient
Electrical Concentration Gradient

Question 22

Resting Membrane Potential:

In all cells a potential difference across the membrane exists:

The inside is ___ which is why it needs the (Na+K+ATPase)
While the MEmbrane Potentials are usually between ___ and ___

A cell with a resting membrane potential is said to be ___

Both inside and the outside of the cell should be ____

Answer 22

Negative

-40mv to -90mv

Polarized

Electrically neutral

Question 23

Resting Membrane Potential:

Factors that determine the resting Membrane potential (4)

Answer 23

Selective permeability of plasma membrane

Leak Channels

Na+K+ATPase Pump

Difference in Ion concentrations

Question 24

Resting Membrane Potential:

Ions that do the most important roles (4)

In the ECF ___ helps to balance ___

In ICF ___(___) balance ___

Answer 24

Na+
K+
Ca++
Cl-

Cl-, Na+

Proteins(neg charge), K+

Question 25

Resting Membrane Potential:

Selective membrane permeability:

a. At rest - Slightly permeable to ___, ___ times more permeable to ___, and freely permeable to ___

b. ___ moves down its concentration gradient easily & Faster than ___

c. Movement of a ___ out leaves a negative charge

Answer 25

Na+, 75, K+, Cl-

K+, Na+

K+

Question 26

Membrane potential :

___ aka. ____Ion movements in both directions across the membrane are equally balanced (net movement = zero)

____ implies no net ion movement

Equation:
E(x) = RT/ZF log inside/outside

R=
T=
Z=
F=

Answer 26

Equilibrium Potential

Ion Flux

Nernst Potential

R= Gas constant
T= Temp. Kelvin
Z= Charge on Ion (Valance)
F=Faraday’s Constant

Question 27

Hwo to use the Nernst’s equation
E(x) = ___ log inside/outside OR outside/inside

Answer 27

-61 mV

Question 28

Nernsst’s equation Examples

-61mV log [14]/[140]

-61mV log [140]/[4]

Answer 28

Na+

K+

Question 29

Net Current Flow (I) equation:

I(x) = g(x) {Em - E(x)}

Where

g=
Em =
E(x) =

Answer 29

g = Ion Conductance
Em = Resting Membrane Potential
E(x) Nernst’s potential

Question 30

Resting Membrane Potential:

At rest, the membrane potential is not changing, so the sum of all currents must equal zero

Otherwise,
Resting Membrane Potential equation:

Em=

R= universal gas constant R=8.314471 J mol -1
T= 0K - 273.15oC
Z= Moles of electrons transferred
F = Faraday’s constant 96, 485.3415 C mol -1

Pa = Permeability of membrane to that ion

Ao = outside

Ai = inside

Answer 30

Em = RT/zF ln ( Pa [A]o + Pb [B]o / Pa [A]i + Pb [B]i )