Page 1: Transport
Cell A
ATP
ADP
ATP
ATP
ATP
ATP
Cell C
ADP
ATP
ATP
ADP
Cell B
ADP
ATP
The three cells shown here are in the same aqueous environment. Each symbol shown represents
thousands of actual molecules, and only those that differ between cells are shown. Use the information in
this diagram to answer the questions below and learn about transport of molecules across cell membranes
1) Fill in the table or relative concentrations below:
Cell A
Concentration
of
Concentration
of
Concentration
of
ATP Used
Cell B
Cell C
Outside of cells
5
5
3
1.5
None
n/a
2. What gradients exist between the outside environment and any of the cells? (Hint: there are 5, total)
3. Compare the molecular contents and membrane molecules in Cells A and B.
What molecular adaptation allows Cell B to have different contents than Cell A? Explain this.
4. Cell C is using active transport. a) Which molecule is being actively transported?
b) In which direction is it being transported: Into the cell or Out of the cell
c) Give a full and specifc explanation for what is happening.
5. Explain the usage of energy based on the data shown here.
How did Cell B use ATP for transport?
In what two ways did Cell C use ATP to allow the transport of a specfiic molecule?
Study at home:
a)  All three cells use a strategy called passive diffusion. Define passive diffusion in a complete sentence.
b)  Cell B uses a strategy called facilitated diffusion. Define facilitated diffusion in a complete sentence.
c)  Cell C uses a strategy called active transport. Define active transport in a complete sentence.
Page 2: Integral Membrane Proteins
The four diagrams shown are different viewpoints on the same integral
membrane protein. The two cross sections are indicated by dashed lines.
Only five amino-acid R-groups are shown with colored shapes.
phospholipid tail
phospholipid head
7. Fill in this chart, using data from the cross sections and diagram above.
R-group
Most likely Most likely
Could be
hydrophilic hydrophobic either
No
Yes
Time Series
This is the substrate
molecule that is transported through
the integral membrane protein
8. If the
R-group were mutated to become hydrophilic,
what might happen to the the transport protein? Explain your
reasoning in terms of the structure and function of the protein.
9. If the
R-group is removed, then the transport protein
moves different types of molecules across the membrane.
Give a reasonable explanation for this result.
10. The time series at right shows a single molecule transporting
through an integral membrane protein. Notice the structural changes!
Why might a mutation in the
change this function? What about a mutation in
?