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TLS Online TPP Program

#Question id: 7152

The size of a cell is generally controlled by the amount of DNA in the nucleus: the more DNA, the larger the cell. What do experiments in which the amount of DNA is doubled (tetraploidy in salamanders) tell us about growth control?

#Unit 5. Developmental Biology
  1. The animals grow to a normal size, and contain only half as many cells, indicating that growth is regulated at the level of absolute size, rather than cell number.
  2. The animals grow to twice the normal size, indicating that growth is regulated at the level of the number of cells present.
  3. The animals end up with cells that are twice as big, but only half as many, resulting in an animal that is half its normal size, indicating that the number of cells is the critical determinant of growth.
  4. The animals grow to a normal size, and contain only half as many cells, indicating that growth is regulated by the total amount of DNA present in an organism.
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TLS Online TPP Program

#Question id: 860

#Unit 1. Molecules and their Interaction Relevant to Biology

Select true ‘T’ AND false ‘F’ about ubiquitinylation

I. These ubiquitin-like modifiers control processes as diverse as nuclear import,

II. Regulated by the ubiquitin-like modifier Sumo, and autophagy,

III. Regulated by the ubiquitin-like modifier Atg8.

IV. For a protein to be efficiently degraded, it must be linked to a chain of at least four tandemly linked ubiquitin molecules in which Lys 34 of each ubiquitin forms an isopeptide bond with the C-terminal carboxyl group of the following ubiquitin.
TLS Online TPP Program

#Question id: 2012

#Unit 4. Cell Communication and Cell Signaling

The DGS-like phenotype can be produced in a specific knockout mouse for HA3, a Hox gene. HA3 is known to be involved in developmental regulation in the mouse. Which of the following would be an appropriate test for following the gene in the mouse progeny?
TLS Online TPP Program

#Question id: 16134

#Unit 13. Methods in Biology

You obtain 6 BACs (of known order, as shown below) and 7 STSs (of unknown order) that derive from a region of mouse chromosome 16 whose genomic sequence has not yet been finished.   
 
By PCR (using 20-bp primers at either end of each STS), you test each of the 6 BACs for the presence (+) or absence (-) of each of the 7 STSs. You obtain the following results:
 
You determine the DNA sequences of PCR products obtained at STS5 using BACs B, C, D, E, and F as PCR templates. The DNA sequences of PCR products obtained using BACs B and C are identical, but they differ by several nucleotide substitutions from the DNA sequences of PCR products obtained using BACs E and F. Oddly, PCR product obtained using BAC D appears to be a mixture of two sequences – one corresponding to the BAC B/ BAC C sequence and the other corresponding to the BAC E/ BAC F sequence. Briefly account for these findings, and explain how a single PCR assay could amplify two different sequences.
TLS Online TPP Program

#Question id: 673

#Unit 1. Molecules and their Interaction Relevant to Biology

How many complete turns are there in an ideal α-helix that contains 15 amino acids and has a pitch of 0.54 nm and a rise of 0.15 nm?
TLS Online TPP Program

#Question id: 19163

#Unit 13. Methods in Biology

Which solvent is usually used for SEC generally use in lab?