A plant with purple flowers is crossed with a plant with white flowers, and the F1 are self-fertilized to produce 105 F2 progeny with purple flowers and 45 with white flowers.

A scientist hypothesized that there are two genes with identical functions that control the dominant trait. The scientist also proposed that the two genes are not linked. The scientist carried out a chi-square test to test the hypothesis. Which one of the following options is the correct chi-square value obtained by the scientist?

#Question id: 4399

#Unit 3. Fundamental Processes

Transcription factors can

a. exhibit cooperative binding.  b. exist as heterodimers.

c. act to repress transcription of transcription factor genes.

d. undergo conformational changes which alter activity.

e. never interact with co-repressors.

#Question id: 4400

#Unit 3. Fundamental Processes

Which is the first factor to bind at the promoter of eukaryotic genes?

a. RNA polymerase

b. TFIIA

c. TFIIB

d. TFIID 

e. TATA box–binding protein

#Question id: 4401

#Unit 3. Fundamental Processes

Which of the following occur(s) during Pol II transcription preinitiation complex formation?

a. TFIIA binds to TFIIB.  b. TFIIB unwinds the DNA.

c. TFIIB contacts both TATA box–binding factor and DNA.

d. DNA bends.

#Question id: 4402

#Unit 3. Fundamental Processes

Chromatin-mediated repression of transcription involves

a. modification of lysine residues in histones. 

b. large, multiprotein complexes.

c. acetylation of histone tails.   

d. deacetylation of histone tails.

#Question id: 4403

#Unit 3. Fundamental Processes

 Which of the following does (do) not require a DNA helicase activity?

a. SWI/SNF function  b. Pol II open-complex formation

c. transcription-factor binding to DNA

d. deacetylation of histone tails

#Question id: 4404

#Unit 3. Fundamental Processes

The yeast two-hybrid system can be used to identify

a. proteins that interact with a known or “bait” protein.

b. proteins that interact with a “fish” domain.

c. cDNAs that encode interacting proteins.

d. co-activators and co-repressors.