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TLS Online TPP Program

#Question id: 1370

H. V. Wilson worked with sponges to gain some insight into exactly what was responsible for holding adjacent cells together. He exposed two species of differently pigmented sponges to a chemical that disrupted intercellular junctions, and the cells of the sponges dissociated. Wilson then mixed the cells of the two species and removed the chemical that caused the cells to dissociate. Wilson found that the sponges reassembled into two separate species. The cells from one species did not interact or form associations with the cells of the other species.

How do you explain the results of Wilson's experiments?

#Unit 4. Cell Communication and Cell Signaling

  1. The two species of sponge had different enzymes that functioned in the reassembly process.

  2. The molecules responsible for cell-cell adhesion (cell junctions) were irreversibly destroyed during the experiment.

  3. The molecules responsible for cell-cell adhesion (cell junctions) differed between the two species of sponge.

  4. One cell functioned as an organizer for each organism, thereby attracting only cells of the same species.

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TLS Online TPP Program

#Question id: 2832

#Unit 2. Cellular Organization

Reporter genes are used to

a. express enzymes that are not easily assayed in cell extracts.

b. express enzymes that are easily assayed in cell extracts.

c. characterize DNA control elements.                     

d. characterize reporter plasmids.
TLS Online TPP Program

#Question id: 2835

#Unit 2. Cellular Organization

An enhancer

a. can be located upstream of a promoter.

b. can be located downstream of a promoter.

c. can be located a variable distance from the promoter.

d. is always located within 1 kb of the promoter.

e. can be cell-type-specific.
TLS Online TPP Program

#Question id: 2836

#Unit 2. Cellular Organization

The fact that a specific protein leaves a “footprint” on a DNA molecule is indicative of
a. a lack of interaction between the specific protein and DNA.
b. protection from DNAse by the specific protein.
c. binding of the specific protein to all types of DNA.
d. binding of the specific protein to a specific sequence of DNA.
TLS Online TPP Program

#Question id: 2837

#Unit 2. Cellular Organization

The C-terminal activation domain of transcriptional activators is capable of
a. binding to DNA.                 
b. stimulating transcription.
c. interaction with other transcriptional machinery.
d. functioning in a fusion with a DNA-binding domain from an unrelated transcriptional activator.
TLS Online TPP Program

#Question id: 2838

#Unit 2. Cellular Organization

You want to study the potential interaction between nucleosome-bound DNA and a specific histone deacetylase. You decide to perform an electrophoretic mobility shift assay (EMSA). You use a 32P end-labelled, linear template DNA that contains two nucleosome positioning sites. You assemble two nucleosomes on the DNA template before incubation with and without the histone deacetylase. For some reactions, you use unmodified nucleosomes. For other reactions, you use nucleosomes that are methylated at lysine 36 of the histone protein H3.

A. The histone deacetylase binds nucleosome bound-DNA in lanes 1, 2, 3, and 4.

B. The histone deacetylase binds nucleosome bound-DNA in lanes 3& 4.

C. The histone deacetylase seems to recognize methylated nucleosomes at lysine 36 of histone H3 in lane 1, 2 & 3 better than unmethylated nucleosomes in lane 4 &5

D. The histone deacetylase seems to recognize methylated nucleosomes at lysine 36 of histone H3 in lane 1 & 2 better than unmethylated nucleosomes in lane 3 &4
TLS Online TPP Program

#Question id: 2839

#Unit 2. Cellular Organization

Consider for correct match

I. All the different members of family of genes and proteins are sufficiently similar in sequence to suggest a common ancestral sequence.

A. Homologous

II. Sequences that presumably diverged as a result of gene duplication

B. Paralogous

III. Sequences that arose because of speciation

C. Orthologous