A female fly, full of fertilized eggs, is swept by high winds to an island far out to sea. She is the first fly to arrive on this island, and the only fly to arrive in this way. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species each of which eats only a certain type of food. None of the species can fly, for their flight wings are absent, and their balancing organs (i.e., halteres) are now used in courtship displays. The male members of each species bear modified halteres that are unique in appearance to their species. Females bear vestigial halteres. The ranges of all of the daughter species overlap. If these fly species lost the ability to fly independently of each other as a result of separate mutation events in each lineage, then the flightless condition in these species could be an example of

#Question id: 2828

#Unit 2. Cellular Organization

A transcriptionally active gene compared with a transcriptionally inactive gene would be expected to

a. contain acetylated histones.           

b. contain unacetylated histones.

c. be sensitive to DNase I.                 

d. be resistant to DNase I.

#Question id: 2829

#Unit 2. Cellular Organization

Scaffold-associated regions

a. are the chromosome attachment points for the mitotic spindle.

b. can insulate transcription units from each other.

c. are the points at which DNA interacts with histone proteins.

d. are found between transcription units.

#Question id: 2830

#Unit 2. Cellular Organization

#Question id: 2831

#Unit 2. Cellular Organization

Specific DNA control elements in promoters can

a. interact with general transcription factors.

b. interact with repressor proteins.                 

c. interact with activator proteins.

d. remain unavailable because of condensed chromatin. 

#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.

#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.