Unformatted text preview: PAGE 1 NAME ____________________________ 1. Two important components that are found in active pancreatic acinar cells are the translocons and signal
peptidase. For each of these components describe: (a) its composition, (b) its exact location in the cell, and (c)
its main function. (6 pts)
An integral trans-membrane protein
Embedded in the ER membrane function:
Provides (1) a specific docking site for the ribosome/mRNA/nascent polypeptide/SRP complex) and (2) the
hydrophobic protein channel through which the newly translated protein is threaded into the lumen of the
protein (enzyme) location:
The enzyme is embedded in the inner leaflet of the ER membrane. function:
Peptidase removes (cleaves) the N-terminal portion of the protein containing the signal peptide. PAGE 2 NAME _____________________________ 2. S. De, et al. (Figure 4) cultured wild type α5β3 LNCaP cells and LNCaP empty vector control cells in soft
agar for 3 days and then microscopically examined several random fields in the culture dishes. (8 pts)
a. Describe the results they obtained. (3 pts)
Compared to vector controls, colonies produced by WT cells were larger and more numerous (~5-fold
b. What results were obtained when wild type α5β3 cells were cultured in soft agar supplemented with antiVEGF antibody? (3 pts)
WT cells cultured in the presence of anti-VEGF antibody produced many fewer colonies (~80% reduction)
c. Describe one negative control for the anti-VEGF experiment. (2 pts)
Grow WT cells in soft agar supplemented with non-specific IgG at the same concentrations and conditions as
used in the anti-VEGF cultures. Compare colony counts to anti-VEGF treated cells.
Or, for 1 point: substitute whatever the IgG was dissolved in, e.g., saline, for the regular treatment (solvent
control). This is usually built in to the experiment and not considered a sufficient control for the presence of
the foreign protein (IgG). Treating the vector only or the S752P cells with anti-VEGF is more of a positive
control in that it verifies the specificity of the IgG (it should have no effect on these non-VEGF-producing cells).
3. Fill in the blank with the term or concept that best fits the description. (6 pts)
a. The type of transport that allows the movement of D-glucose into a cell against its concentration gradient.
Secondary active transport
b. The type of transport that may generate an electro-chemical gradient.
Primary active transport
c. The type of transport kinetics that is characteristic of diffusion facilitated by channel proteins.
d. The type of carrier protein that is capable of simultaneously transporting two different solutes in the same
e. The type of transport mechanism that is often regulated by “voltage-gating”.
Facilitated diffusion mediated by a channel protein.
f. One type of transport mechanism that is mediated by a transmembrane integral protein.
Any facilitated type diffusion: channel protein or transporter protein; primary active transport;
secondary active transport. ...
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- Summer '08
- Ion channel, Secondary Active Transport, WT cells