3. âĸ barrier to water and water-soluble substances
ions glucose
urea
Lipid Bilayer:
CO2
O2
N2
halothane
H2O
4. Ion Concentrations
īThe maintenance of solutes on both sides of the
membrane is critical to the cell and homeostasis
īHelps to keep the cell from rupturing
īConcentration of ions on either side varies widely
īNa+
and Cl-
are higher outside the cell
īK+
is higher inside the cell
īMust balance the number of positive and
negative charges, both inside and outside cell
5.
6.
7. īComposition of ECF is maintained by different
systems like nervous , endocrine, CVS, GIT, renal ,
respiratory in a coordinated fashion
īComposition of ICF is maintained by cell
membrane which mediates the transport of
materials b/w ICF and ECF through different
transport mechanisms.
8.
9. Membrane Transport Proteins
īMany molecules must move back and forth from inside
and outside of the cell
īMost cannot pass through without the assistance of
proteins in the membrane bilayer
īPrivate passageways for select substances
īEach cell has specific set of proteins
11. Permeability of a membrane
Anything that passes between a cell and the
surrounding ECF must be able to pass through the
plasma membrane.
īIf a substance can pass thru the membrane, the
membrane is said to be permeable to that substance;
īif a substance cannot pass, the membrane is
impermeable to it.
ī The plasma membrane is selectively permeable in
that it permits some substances to pass through while
excluding others.
12. Impermeable Membranes
īIons and hydrophilic
molecules cannot easily
pass thru the
hydrophobic membrane.
īSmall and hydrophobic
molecules can
13. 2 Major Classes of proteins
īCarrier proteins â move the solute across the membrane
by binding it on one side and transporting it to the other
side
īRequires a conformation change
īChannel proteins â small hydrophilic pores that allow for
solutes to pass through (watery spaces)
īUse diffusion to move across
īAlso called ion channels when only ions moving
īCalled aquaporins if water is moving thru them
15. Carrier vs Channel
īChannels, if open, will let solutes pass if they have the
right size and charge
īTrapdoor-like
īCarriers require that the solute fit in the binding site
carriers are specific like an enzyme and its substrate
16. īBoth the channel proteins and
carrier proteins are usually highly
selective in the types of molecules
or ions that are allowed to cross the
membrane.
īThese proteins are also present in
membranes of cell organelles
18. Membrane Ion Channels
īļPassive, or leak, channels â always open
īļGated which open and close
īļChemically (or ligand)-gated channels â open
with binding of a specific neurotransmitter (the
ligand)
īļVoltage-gated channels â open and close in
response to changes in the membrane potential
īļMechanically-gated channels â open and close in
response to physical deformation of receptors
Types of plasma membrane ion channels
22. KEY WORDS
īSolvent: (relatively large amount of a substance which is
the dissolving medium; in the body is water).
īSolute: (relatively small amount of a substance which is
the dissolved substance and it dissolves in the solvent).
īSolution: is a homogenous mixture of a solute in a
solvent.
īConcentration: of a solvent is the amount of solute
dissolved in a specific amount of solution.
īConcentration gradient: difference in the concentration
of a solute on two sides of a permeable membrane.
īEquilibrium: exact balance between 2 opposing forces.
īDynamic: continuous motion or movement.
23. Types of Cellular Transport
ī 1 Passive Transport
cell doesnât use energy
1. Diffusion (simple & facilitated)
2. Osmosis
ī 2 Active Transport
cell does use energy
1. Primary active transport
2. Secondary active transport
high
low
This is
gonna
be hard
work!!
high
low
Weeee!!!
âĸAnimations of Active
Transport & Passive
Transport
26. Two major modes of membrane transport
I. Simple (Passive)DiffusionI. Simple (Passive)Diffusion
no carriers is involvedno carriers is involved
There are two major modes of mediated diffusion:
passive transport (or facilitated diffusion) and active
transport
II. Mediated DiffusionII. Mediated Diffusion
is carried out by proteins,is carried out by proteins,
peptides, and small molecularpeptides, and small molecular
weight carriersweight carriers
((ions, uncharged organic compounds,
peptides, and even proteins can be
transported)
âĸMolecules that are transported through the
cell membrane via simple diffusion include
organic molecules, such as benzene and
small uncharged molecules, such as H2O, O2,
N2, urea, glycerol,and CO2
27. Diffusion
īMolecules are in continuous random motion
(Brownian motion)
īEvident mostly in liquids and gases whose molecules
are free to move
īGreater the concentration of molecules greater the
likelihood of collision and movement to chamber
with low concentration
28.
29. 1)The net movement of particles
2)from a region of higher concentration
3)to a region of lower concentration,
4)down the concentration gradient
. The energy that causes diffusion is the energy of the
normal kinetic motion of molecules
Diffusion
High concentration Low concentration
30. īDiffusion can occurs either
through the lipid membrane or
through the carrier proteins
or through channel proteins
33. 1: SIMPLE DIFFUSION
īSimple diffusion means the net
movement of molecules from higher
concentration to lower conc. through
âPROTEIN CHANNELSâ or
âINTERCELLULAR SPACEâ of cell
membrane without carrier proteins
and energy
34.
35. Diffusional equilibrium
īNet movement ceases
when concentration of
particles is equal
everywhere within the
solution although
random movement of
the particles continues
38. īSimple diffusion occur through
the cell membrane by two
pathways
ī1) lipid soluble substance through the interstices of
lipid bilayer
ī2) through channel proteins if water soluble and ion
and small
39.
40. A: SIMPLE DIFFUSION THROUGH LIPID BILAYER
īCO2
īO2
īN2
īFatty acids
īAlcohol
They all are lipid soluble (uncharged and also non
polar) and can diffuse through the membrane
41. TRANSPORT OF H2O
ī H2O passes through lipid bilayer because its size is
small and also thru aquaporins
42. SIMPLE DIFFUSION THROUGH PROTEIN CHANNEL
īLarger water soluble substances and
charged particles (electrolytes)
passes through protein channels , not
through lipid bilayer.
43. Ion Channels
īIon channels are very specific with regards
to pore size and the charge on the molecule
to be moved
īMove mainly Na, K, Cl and Ca
44. Reason of impermeability
of charge particles
īThey are hydrated ions so bigger size.
īOuter pole of lipid bilayer have
negative chargeâĻâĻâĻ
46. Selective permeability of protein
channels
īIt may be due to :
īDiameter of the channel
īIts shape
īNature of electric charges
47. Gating of channels
īGating provides in controlling the ion permeability
of the channels
īThe opening and closing of gates are controlled in
two ways:
ī1) VOLTAGE GATING
ī2) LIGAND GATING
ī3) MECHANICAL GATING
48.
49. Voltage Gated channels in
Simple Diffusion:
Sodium Channels:
âĸ0.3 by 0.5 nm in diameter
âĸNegatively charged on the inside
âĸBecause of the negative charges they
pull the positively charged sodium ion
inside, away from the water molecule.
Potassium channel:
âĸ0.3 by 0.3 nm in diameter
âĸNo negative charge on the inside
âĸPull the hydrated K ion inside. As no
negative charge on the inside of the
channel, no attractive forces for the
Na ionâĻ also, Na ions hydrated form is
far too bigâĻ.
53. Diffusion of low lipid soluble
substance and too large for channels
īLike glucose pass thru the carrier
proteins
īe.g. facilitated diffusion and active
transport
54. Factors affecting rate of simple
diffusion
1 Permeability of membrane
2 Concentration difference
3. Pressure difference
4 Electrical difference
5. Surface area of the membrane
6. molecular weight of the
substance
7. Thickness of the membrane
55. Factors that affect
the net rate of diffusion:
1. Concentration difference (Co-Ci)
net diffusion â D (Co-Ci)
Figure 4-8; Guyton & Hall
56. The steeper the concentration gradient, the faster diffusion takes
place
Fast rate of
diffusion
Steeper concentration gradient
Concentration Gradient
Less steep concentration gradient
Slow rate of diffusion
58. 3. Pressure difference
âĸ Higher pressure results in increased energy
available to cause net movement from high to low
pressure.
Figure 4-8; Guyton & Hall
66. 2: FACILITATED DIFFUSION
Definition: is the transport mechanism which require
âCARRIER PROTEINâ
Mechanism:
1. Molecule + CARRIER PROTEIN (loosely bound)
2. Conformational change in carrier protein
3. Molecule detached from carrier
4. No energy or ATP required
67.
68. FACILITATED DIFFUSION
Glucose
Amino acids
Other simple carbohydrates such as :
Galactose
Mannose
Arabinose
Xylose.
All require âcarrier proteinâ for their transport, so
called âcarrier mediated diffusionâ
69.
70. īMeans by which glucose is transported into cells
muscles liver and RBCs
ī Insulin increases number of carriers for glucose in
plasma membrane of different cells
74. Saturation: A limited no. of
carrier binding sites are available
within a particular plasma membrane
for a specific substance. Thus, there is
a limit to the amount of substance a
carrier can transport across the
membrane in a given time. This is
called Transport Maximum (Tm).
75.
76. Mediated-Transport Systems
In simple diffusion,
flux rate is limited
only by the
concentration
gradient.
In carrier-
mediated
transport, the
number of
available carriers
places an
upper limit
on the flux rate.
80. How does water get through the HYDROPHOBIC Plasma
membrane?
Answer: Even though water is polar and so highly
insoluble in the membrane lipids, it readily passes
through the cell membrane thru 2 ways:
1.Water molecules are small enough to move
through the spaces created between the
phospholipid moleculesâ tails
2.In many cells, membrane proteins form
aquaporins, which are channels specific for the
passage of water. About a billion water molecules
can pass in single file through an aquaporin channel
in one second. (renal tubules)
81. Osmosis
Definition:
The diffusion of water molecules
through a partially permeable membrane
from a solution of high water concentration
to a solution of lower water concentration
Down the concentration gradient
: sucrose
:water
molecules
Partially permeable
membrane
82. Chapter 3 The Plasma
Membrane and Membrane
Potential
Human Physiology by Lauralee
Sherwood Š2007 Brooks/Cole-
Thomson Learning
Fig. 3-9, p. 63
83. OSMOSIS
īDiffusion of water through the semi permeable
membrane from a solution of higher water
concentration towards a solution of lower water
concentration
84. Partially-permeable
membrane
More free water molecules on this side
of membrane
Water-solute particle is too
large to pass through
membrane
Free water molecules diffuse in this direction
85. Osmosis: due to difference in
net hydrostatic pressure
īThe hydrostatic pressure of pure water is higher than that of
solution on right
86. As this column rises higher, it will
exert increasing pressure. At
some
point that hydrostatic pressure
will
reach an equilibrium, at which
point
no more net water will move across
the
semi-permeable membrane.
This pressure is the âosmotic
pressureâ
of the starting solution on the
right.
87. Osmotic pressure
īThe amount of pressure required to stop further the
process of osmosis is called osmotic pressure Driving
force is the osmotic pressure caused by the
difference in water pressure
88. Osmotic pressure
īThe greater the solute conc. of a
solution, the greater its osmotic
pressure.
īOR
īThe greater the no. of ion/molecule
when dissolved greater the osmotic
pressure.
89.
90. Example
īSeparate pure
water from a sugar
solution with semi
permeable
membrane
īBoth have same
hydrostatic pressure
īOsmosis take water
from side 1 to side 2
because solution on
side 1 has more
hydrostatic pressure
91. īWill all water go to side 2?
īNo it stops after some time. This is the
equilibrium state
92. īAs water moves by osmosis to
side 2.
īSolution on side 2 has two
tendencies now
īTendency to push water back to
side 1 due to greater hydrostatic
pressure
īTendency to pull water by
osmosis back to side 2
īEquilibrium is achieved when
tendency to pull water to side 1
and to push water into side 2
balances out
Equilibrium state
93. âĸ Osmotic pressure depends on the number of
solutes/unit volume (rather than chemical nature of
solutes or mass of the particles)
94. REASON
īEach particle in a solution regardless of its mass
exerts on average the same amount of pressure
against the membrane
ī K.E. = mv2
2
If more mass then less velocity and vice versa so KE on
average is same for both small and large particle
96. Solutes are dissolved particles in
solution (any type)
hypersmotic
(higher osmotic pressure)
hyposmotic
(lower osmotic pressure)
97. osmole
īTo express the concentration of a solution in terms of
no. of particles the unit osmole is used in place of
grams
ī1 osmole is 1 gram molecular weight of osmotically
active solute.
98. īmolarity - moles of solute / liters of solvent
(moles/liter = Molar)
īmole - grams of substance = mol. wt. substance
ī l mole H = 1 gram H
ī1 mole C = 12 grams C
ī1 mole NaCl = 58 grams NaCl
ī1 mole C6H12O6 = 180 grams C6H12O6
ī58 grams NaCl/l liter water = 1 mole NaCl/liter = 1
Molar NaCl (lM NaCl)
ī180 g Glucose/1 liter water = 1 mole glucose/liter = 1
Molar glucose (1M Glucose)
99. Osmolarity/Osmolality
īTo describe the total number of osmotically
active particles per litre of solution term
osmolarity is used
īIT IS OSMOLES PER LITER OF SOLUTION
īThe higher the osmolarity, the greater the
osmotic pressure of the solution.
100. īTwo solutions can have the same molarity but may have
different osmolarities. E.g.
OsM of 1 M glucose solution =1 OsM
OsM of 1 M NaCl solution = 2 OsM
101. īThe solution that has I osmole of solute dissolved in
each Kg of water have an osmolality of 1 osmole per
liter.
īThe solution that has 1/1000 osmoles dissolved per Kg
has an osmolality of I milliosmole
īThe normal osmolarity of ECF and ICF is 300mOsm
per Kg of water
102. Relation between osmolarity and molarity
mOsm (millisomolar) = index of the concn
or mOsm/L of particles per liter soln
mM (millimolar) = index of concn of
or mM/L molecules per liter soln
150 mM NaCl = 300 mOsm
300 mM glucose = 300 mOsm
103. Relation of osmolality to osmotic
pressure
īAt normal body temp. concentration of 1 osmole per
liter will cause osmotic pressure of 19300 mm Hg
osmotic pressure in the solution
ī1 milli osmole will be equivalent to 19.3mm Hg
osmotic pressure
īTotal osmotic pressure = 300 x 19.3 = 5790mmHg
īWe take 5500 0smotic pressure because many ions
in the body fluids are highly attracted to one another
and therefore canât exert their full osmotic pressure
104. Tonicity is a relative term
īIsotonic SolutionIsotonic Solution - both solutions have same
concentrations of solute
īHypotonic SolutionHypotonic Solution - One solution has a lower
concentration of solute than another.
īHypertonic SolutionHypertonic Solution - one solution has a
higher concentration of solute than another.
105. Hypotonic â The solution on one side of a membrane where the solute
concentration is less than on the other side. Hypotonic Solutions contain a low
concentration of solute relative to another solution.
Hypertonic â The solution on one side of a membrane where the solute
concentration is greater than on the other side. Hypertonic Solutions contain a
high concentration of solute relative to another solution.
106. RED CELL IN ISOTONIC
SOLUTION
īCytoplasm and
solution outside the
cell has same
concentration of
solutes so no net
movement of water so
cell maintain its
shape
107. Red blood cell in
Low water potential 1. Cytoplasm has higher
water potential
compared to the
solution outside the
cell.
2. Water leaves by
osmosis
3. Cell shrinks and little
spikes appear on cell
surface membrane.
(Crenation)
108. Red blood cell in
High water potential 1. Cytoplasm has lower
water potential
compared to solution
outside cell
2. Water enters by
osmosis
3. Animal cell will swell
and may bursts as it
does not have a cell
wall to protect it.
109. Special categories of transport
1. BULK TRANSPORT:
It is the transport mechanism in
which large quantity of substances
transported from high pressure to
low pressure e.g. exchange thru
capillary membrane
110. Membrane Transport
īVesicular transport
īMaterial is moved into or out of the cell wrapped in
membrane
īActive method of membrane transport
īTwo types of vesicular transport
ī Endocytosis
ī Process by which substances move into cell
ī Pinocytosis â nonselective uptake of ECF
ī Phagocytosis â selective uptake of multimolecular particle
ī Exocytosis
ī Provides mechanism for secreting large polar molecules
111. Transport in Vesicles
īRequires energy (ATP)
īInvolves small membrane sac
īEndocytosis: importing materials into cell
īPhagocytosis: ingestion of particles such as bacteria
into white blood cells (WBCs)
īPinocytosis: ingestion of fluid
īExocytosis: exporting materials
111
113. ENDOCYTOSIS
īLarge molecule or macromolecules transported by
endocytosis.
īEndocytosis are of 3 types
a. Pinocytosis
b. Phagocytosis
c. Receptor mediated endocytosis
114. PINOCYTOSIS (Cell drinking)
1. non selective uptake of particle( in the form of
droplet fluid ECF) bind with outer surface of
membrane.
2 Cell membrane evaginate around the
droplets
3 It is detached from cell membrane forms
ENDOSOME.
115. PINOCYTOSIS (Cell drinking) Cont..
ī4. Primary lysosomse attach with edosome
,converted into secondry lysosomes.
ī5. Hydrolytic enzymes present in secondary
lysosome becomes activated and digest the
content of endosome
121. Chapter 3 The Plasma
Membrane and Membrane
Potential
Human Physiology by Lauralee
Sherwood Š2007 Brooks/Cole-
Thomson Learning
Table 3-2c, p. 74
122. ACTIVE TRANSPORT
Definition:
Active transport is a carrier-mediated transport wherein
molecules and ions are moved against their concentration
gradient across a membrane and requires expenditure of
energy.
Active transport is divided into 2 types according to the
source of the energy used.
124. īIn both instances, transport depends on
carrier proteins. , the carrier protein functions
differently from the carrier in facilitated diffusion
because it is capable of imparting energy to the
transported substance to move it against the
electrochemical gradient by acting as an enzyme
and breaking down the ATP itself.
125. Primary Active Transport
âĸ The primary active transport carriers are termed as pumps.
âĸmolecules are âpumpedâ against a concentration
gradient at the expense of energy (ATP)
â direct use of energy
Secondary Active Transport
âĸ transport is driven by the energy stored in the
concentration gradient of another molecule (Na+
)
â indirect use of energy
126. Types of Active Transport:
In primary active transport, the energy is derived
directly from breakdown of adenosine triphosphate
(ATP) or from some other high-energy phosphate
compound.
In secondary active transport, the energy is derived
secondarily from energy stored in the form of an ion
concentration gradient between the two sides of a cell
membrane, created originally by primary active
transport. Thus, energy is used but it is âsecondhandâ
energy and NOT directly derived from ATP.
127. Primary Active Transport
īIn primary active transport, energy in the form of ATP is
required to change the affinity of the carrier protein binding
site when it is exposed on opposite sides of plasma membrane.
īThe carrier protein also acts as an enzyme that has ATPase
activity, which means it splits the terminal phosphate from an
ATP molecule to yield ADP and inorganic phosphate plus free
energy.
Examples:
1. Sodium-Potassium Pump (every cell).
2. Hydrogen pump: occurs at 2 places in the human body:
- in the gastric glands of the stomach
- In the kidneys
3. Ca pump (muscles)
128. Na-K PUMP:
âĸ It has the following
structure:
1. 3 receptor sites for
binding Na ions on the
portion of the protein
that protrudes to the
inside of the cell.
2. 2 receptor sites for
potassium ions on the
outside.
3. The inside portion of this
protein near the sodium
binding site has ATPase
activity.
131. FUNCTIONS OF SODIUM-POTASSIUM PUMP:
1. Control the Volume of each cell: It helps regulate cell
volume by controlling the concentrations of solutes
inside the cell and thus minimizing osmotic effect that
would induce swelling or shrinking of the cell. If the
pump stops, the increased Na concentrations within the
cell will promote the osmotic inflow of water, damaging
the cells.
2. Electrogenic nature of the pump: It establishes Na and
K concentration gradients across the plasma membrane
of all cells; these gradients are critically important in the
ability of nerve and muscle cells to generate electrical
signals essential to their functioning.
3. Energy used for Secondary active transport: The steep
Na gradient is used to provide energy for secondary
active transport.
132. 2. Ca2+
ATPase
âĸ present on the cell membrane and the sarcoplasmic
reticulum
âĸ maintains a low cytosolic Ca2+
concentration
133. âĸ found in parietal cells of gastric glands (HCl secretion)
and intercalated cells of renal tubules (controls blood
pH)
134. Examples of Primary Active Transport Pumps:
1) Na+
/K+
-ATPase pump
- found in the plasma membrane
- 3 Na+
are pumped out of cytosol and 2 K+
are pumped into the cytosol
2) Ca+2
-ATPase pump
- found in the plasma membrane, & endoplasmic reticulum membranes
- pumps Ca+2
out of cytosol and either into the ER or the extracellular fluid
3) H+
-ATPase
- found in the plasma membrane, lysosomes, & mitochondria inner
membrane
- pumps H+
out of the cell and into extracellular fluid
- pumps H+
into lysosomes to be used as digestive enzymes
- used in the electron transport chain of mitochondria
4) H+
/K+
-ATPase
- used in acid secreting cells of the kidneys and stomach
- pumps one H+
out of cell and one K+
into the cell
135. Saturation
âĸ similar to facilitated diffusion
âĸ rate limited by Vmax of the transporters
Energetics
âĸ up to 90% of cell energy expended for active
transport!
Competition
Specificity
136. Secondary Active Transport
1. Co-transport (co-porters): substance is
transported in the same direction as the âdriverâ ion (Na+
)
Examples:
inside
outside
Na+
AA Na+ gluc 2 HCO3
-Na+
- co-transport and counter-transport -
137. 2. Counter-transport (anti-porters): substance is
transported in the opposite direction as the âdriverâ ion (Na+
)
Examples:
Na+
Ca2+
Na+
H+
Cl-
/H+
Na+
/HCO3
-
outside
inside
138.
139. SECONDARY ACTIVE
TRANSPORT
CO-TRANSPORT
īSymport
īNa moves downhill
īMolecule to be co-
transported moved in the
same direction as Na, i.e. to
the inside of the cell.
īE.g. Na with glucose and
amino acids.
īSite: intestinal lumen and
renal tubules of kidney.
COUNTER TRANSPORT
īAnti-port
īNa moves downhill
īMolecule to be counter-
transported moves in the
opposite direction to Na, i.e. to
the outside of the cell.
īE.g. Na with Calcium and
Hydrogen ions.
īSite: Na-Ca counter transport in
almost all cells of the body and
Na-H+
in the proximal tubules of
the kidney.
140. Types of Secondary Transporters
ī Symporters (two solutes move(two solutes move
in same direction) Lac-in same direction) Lac-
permease, Napermease, Na++
/glucose/glucose
transporter)transporter)
ī AntiportersAntiporters (two solutes move(two solutes move
in opposite directionsin opposite directions
NaNa++
/Ca/Ca2+2+
exchanger)exchanger)
ī UniportersUniporters (mitochondrial Ca(mitochondrial Ca2+2+
uniporter and NHuniporter and NH++
44-transporter-transporter
in plants require Hin plants require H++
gradient)gradient)
141. Transcellular Transport of Glucose / AA
Na+
glucose
AA
Na+
low high
epitheliumlumen
extracellular
fluid
Na+
Na+
K+
K+
AAAA
glucoseglucose
low
142. Diffusion Active Transport
âĸ occurs down a concn.
gradient
âĸ no mediator or involves
a âchannelâ or âcarrierâ
âĸ no additional energy
âĸ occurs against a concn.
gradient
âĸ involves a âcarrierâ
âĸ requires ENERGY
Figure 4-2; Guyton & Hall
Uncharged or nonpolar molecules (such as O2, CO2, and fatty acids) are highly lipid soluble and readily permeate the membrane. Charged particles (ions such as Na and K) and polar molecules (such as glucose and proteins) have low lipid solubility but are very soluble in water. The lipid bilayer serves as an impermeable barrier to particles poorly soluble in lipid.
What u see is the motion that all molecules present in the body are undergoingâĻ. Only at absolute zero does the motion stop. Molecule A will collide with Molecule B âĻ It will slow down a little while Molecule B will accelerate a littleâĻ and so onâĻ This will go on till they spread out gradually and are evenly distributed. Now, equilibrium has occurred and diffusion stops. The molecules are still in motion but the concentration has equalized everywhereâĻ. This is called dynamic equilibrium.
A good example is a drop of blue ink being dropped into a beaker containing water. The way the blue ink spreads till it evenly spreads out is called diffusionâĻ..
Another good example is open bottle of cologne in a roomâĻ the cologne spreads out in the room, u can smell it after a while even at the other end of the room.
Occurs at capillary membrane. Higher pressure in the capillary facilitates the diffusion of molecules into the tissues.
Pressure actually means the sum of all the forces of the different molecules striking a unit area of membrane at a given instant.
Facilitated DiffusionâĻ.
Figure 3.9: Relationship between solute and water concentration in a solution.
(a) Pure water. (b) Solution.
To put the pump in perspective: when 2 potassium ions bind on the outside of the carrier protein and three sodium ions bind on the inside, the ATPase
function of the protein becomes activated. This then cleaves one molecule of ATP, splitting it to adenosine diphosphate (ADP) and liberating a high-energy
phosphate bond of energy. This liberated energy is then believed to cause a chemical and conformational change in the protein carrier molecule, extruding the three sodium ions to the outside and the two potassium ions to the inside.