11

Question 1

The membrane is a natural barrier to _________ because ________.

Answer 1

Polar and charged molecules, the membrane’s interior contains nonpolar and hydrophobic fatty acid tails that do
not interact well with polar and charged molecules.

Question 2

O2 and steroid hormones (such as testosterone) easily cross the membrane
because these molecules are _______ (chemical property). Since the core of the membrane is _______ (chemical property), the membrane does not repel these molecules.

Answer 2

Nonpolar

Question 3

Glucose and Na+ cross the membrane poorly or not at all because these molecules are _______ (chemical property(ies)). Since the core of the membrane is _______ (chemical property), the membrane repels these molecules.

Answer 3

Polar, nonpolar

Question 4

Membrane transport
Moving from an area of high concentration to low, a molecule is:
1. Moving _______ the concentration gradient
2. Uses _______ transport

Answer 4

With, passive

Question 5

Membrane transport
Moving from an area of low concentration to high, a molecule is:
1. Moving _______ the concentration gradient
2. Uses _______ transport
3. The movement is energetically _______

Answer 5

Against, active, unfavorable

Question 6

Membrane transport
To determine the type of transport that occurs, one needs to consider:
1.
2.

Answer 6

Concentration gradient (moving with or against the gradient), Chemical property of molecule (nonpolar vs polar or charged or large)

Question 7

Transporter characteristics & Energetic coupling
1. _______: ATP is dephosphorylated and a
membrane protein is phosphorylated. This causes the membrane protein to change shape to allow for the movement of a molecule in an unfavorable direction.

Answer 7

How ATP is used in membrane transport

Question 8

Transporter characteristics & Energetic coupling
2. _______: A transporter protein
must specifically bind to each of the molecules in one compartment, and
then the protein must change shape in order to release the molecules into
a different, specific compartment.

Answer 8

How the transport of molecules can be coupled

Question 9

If provided a model of a membrane transport process, describe how you would
determine:
1. Whether passive or active transport is required:
i.
ii.

Answer 9

Pa,ssive transport if molecule movements are towards equilibrium (high to low), Active transport if molecule movements are away from equilibrium (low to high)

Question 10

If provided a model of a membrane transport process, describe how you would
determine:
2. If passive transport, whether a protein is required:
i.
ii.

Answer 10

If the molecule is small and nonpolar, simple diffusion is used (no protein)

If the molecule is polar, charged, or large: facilitated diffusion through a carrier or channel is needed

Question 11

If provided a model of a membrane transport process, describe how you would
determine:
3. If active transport, what is the energy source:

Answer 11

ATP or the favorable movement of another molecule through the same transporter protein