Biol 4087 Exam 3 Part 2 (Chapters 13 & 15) Exam with
Solutions
Pumps, carriers, channels and the membrane permeability
barrier
passive vs. active transport/ primary vs secondary transport
Concentration/electrochemical gradients are a source of
energy
Chapter 13 major concepts
P-type ATPases and ABC transporter pumps.
Channels rapid, yet selective, mediate movement of ions
across membranes.
Ion channels “gating”.
action potential.
molecules that can pass through cell membranes because they
What are lipophilic molecules?
dissolve in the lipid bilayer
Process by which lipophilic molecules move across the
What is simple diffusion? membrane, down a concentration gradient, from regions of high
to low concentration
• process by which polar molecules are transported across the
What is facilated diffusion?
membrane, down a concentration gradient, by a specific channel
Why is facilitated diffusion also because the energy driving the ion movement originates from
called passive transport? the ion gradient itself
Process by which molecules are transported across the
What is active transport? membrane, against a concentration gradient, with the input of
energy from another source
• The free energy required to move an uncharged solute from
side 1 of a membrane (where it is present at a concentration of c1)
to side 2 of a membrane (where it is present at a concentration of
What is the free-energy change c2) is given by
equation of an Uncharged
solute? ΔG = RT ln (c2 /c1)
where R is the gas constant (8.315 × 10−3 kJ mol−1 deg−1) and T is
the temperature in kelvins
Which transport has a positive Active transport
ΔG?
Which transport has a negative Passive transport
ΔG?
what is electrochemical the sum of the concentration and electric terms
potential (membrane potential)?
, The free energy required to move a charged species from side 1
of a membrane to side 2 of a membrane is given by
What is the Free-Energy
ΔG = RT ln (c2/c1) + ZF ΔV
Change of a Charged Species
equation?
where Z is the electrical charge of the species, ΔV is the
potential voltage across the membrane, and F is the Faraday
constant (96.5 kJ V−1 mol−1 )
membrane proteins that catalyze the active transport of ions
what are pumps?
against their electrochemical gradients
True
- most animal cells contain a high
concentration of K+ and a low
concentration of Na+ relative to the
T/F: ATP hydrolysis can power
external medium.
transport of ions
Powered by Na+ ,low K+, and ATPase
- energy is required to generate these
gradients
family of ATPases that form a
phosphorylated aspartate
what are P-type ATPases?
intermediate (phosphorylaapartate)
-Na+-K+ ATPase
-sarcoplasmic endoplasmic reticulum
Ca2+ ATPase (SERCA) = pumps Ca2+
What are some examples of P-
out of the cytoplasm and into the
type ATPases?
sarcoplasmic reticulum of muscle cells
-gastric H+-K+ ATPase = pumps protons
into the stomach to lower the pH to 1.0
–one with the ion binding site facing into the cell
what two conformations do – one with the binding site facing out of the cell
pumps exist in?
∆G of ATP hydrolysis is coupled to the interconversion of the two
conformations to pump ions across a membrane.
Solutions
Pumps, carriers, channels and the membrane permeability
barrier
passive vs. active transport/ primary vs secondary transport
Concentration/electrochemical gradients are a source of
energy
Chapter 13 major concepts
P-type ATPases and ABC transporter pumps.
Channels rapid, yet selective, mediate movement of ions
across membranes.
Ion channels “gating”.
action potential.
molecules that can pass through cell membranes because they
What are lipophilic molecules?
dissolve in the lipid bilayer
Process by which lipophilic molecules move across the
What is simple diffusion? membrane, down a concentration gradient, from regions of high
to low concentration
• process by which polar molecules are transported across the
What is facilated diffusion?
membrane, down a concentration gradient, by a specific channel
Why is facilitated diffusion also because the energy driving the ion movement originates from
called passive transport? the ion gradient itself
Process by which molecules are transported across the
What is active transport? membrane, against a concentration gradient, with the input of
energy from another source
• The free energy required to move an uncharged solute from
side 1 of a membrane (where it is present at a concentration of c1)
to side 2 of a membrane (where it is present at a concentration of
What is the free-energy change c2) is given by
equation of an Uncharged
solute? ΔG = RT ln (c2 /c1)
where R is the gas constant (8.315 × 10−3 kJ mol−1 deg−1) and T is
the temperature in kelvins
Which transport has a positive Active transport
ΔG?
Which transport has a negative Passive transport
ΔG?
what is electrochemical the sum of the concentration and electric terms
potential (membrane potential)?
, The free energy required to move a charged species from side 1
of a membrane to side 2 of a membrane is given by
What is the Free-Energy
ΔG = RT ln (c2/c1) + ZF ΔV
Change of a Charged Species
equation?
where Z is the electrical charge of the species, ΔV is the
potential voltage across the membrane, and F is the Faraday
constant (96.5 kJ V−1 mol−1 )
membrane proteins that catalyze the active transport of ions
what are pumps?
against their electrochemical gradients
True
- most animal cells contain a high
concentration of K+ and a low
concentration of Na+ relative to the
T/F: ATP hydrolysis can power
external medium.
transport of ions
Powered by Na+ ,low K+, and ATPase
- energy is required to generate these
gradients
family of ATPases that form a
phosphorylated aspartate
what are P-type ATPases?
intermediate (phosphorylaapartate)
-Na+-K+ ATPase
-sarcoplasmic endoplasmic reticulum
Ca2+ ATPase (SERCA) = pumps Ca2+
What are some examples of P-
out of the cytoplasm and into the
type ATPases?
sarcoplasmic reticulum of muscle cells
-gastric H+-K+ ATPase = pumps protons
into the stomach to lower the pH to 1.0
–one with the ion binding site facing into the cell
what two conformations do – one with the binding site facing out of the cell
pumps exist in?
∆G of ATP hydrolysis is coupled to the interconversion of the two
conformations to pump ions across a membrane.
