TLS Online TPP Program

#Question id: 1240


Pull-down assays using proteins that ONLY bind to the GTP-bound version of the small G-protein can be used to detect when small G proteins like Rac1 have been activated by various growth factors.  You were given two lysates, one having been treated with platelet-derived growth factor (PDGF) and the other not treated with PDGF. This method is similar to performing co-IPs, so based on that knowledge, which of the following steps is erroneous?

#Unit 4. Cell Communication and Cell Signaling
  1. To assay for levels of active Rac1, PAK1-beads (the protein that only binds GTP-bound Rac1-conjugated to beads similar to Nickel beads) are added to each of the lysates described above and incubated on a rocking platform (on ice). 

  2. The tubes are vortexed well, loading buffer is added, and the samples are heated to aid in protein denaturation.

  3. The samples are loaded and analyzed by SDS-polyacrylamide gel electrophoresis, then the proteins are transferred to a membrane. 

  4. The membrane (a.k.a. blot) will be probed with the anti-Rac antibody.

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TLS Online TPP Program

#Question id: 9200

#Unit 9. Diversity of Life Forms

During the inventory of bacterial genes present in the Sargasso Sea, a deep isolated area in the middle of the Atlantic Ocean, a research team concluded that at least 1,800 bacterial species were present. Based on what you might predict about the habitat structure of such an area, what kind of bacterial diversity would you expect to see in tropical coral reef waters?

TLS Online TPP Program

#Question id: 9201

#Unit 9. Diversity of Life Forms

Erwin and Scott used an insecticidal fog to knock down insects from the top section of a L. seemannii tree. The researchers identified over 900 species of beetles among the individuals that fell. Erwin also projected that this entire tree from top to bottom is host to about 600 arthropod species that are unique to this tree species and not found on any other tree species. There are approximately 50,000 species of tropical trees. Although it could not be entirely accurate, what would be the best way to estimate the total number of arthropod species?

TLS Online TPP Program

#Question id: 9202

#Unit 9. Diversity of Life Forms

Which of the following statements regarding extinction is accurate?

TLS Online TPP Program

#Question id: 9203

#Unit 9. Diversity of Life Forms

The human impact that scientists determined has caused the most extinctions on record is ________, and beyond further losses from this impact, the other impact with the largest potential to cause future extinctions is ________.

TLS Online TPP Program

#Question id: 9204

#Unit 9. Diversity of Life Forms

Which of the following observations provides the best evidence of a biodiversity crisis?

TLS Online TPP Program

#Question id: 9205

#Unit 9. Diversity of Life Forms

Which of the following terms includes all of the others?