TLS Online TPP Program

#Question id: 2228


Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this fact most probably mean?

#Unit 2. Cellular Organization
  1. Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.

  2. The high concentration of protons in the ancient atmosphere must have necessitated a pump mechanism.

  3. Cells of each domain evolved proton pumps independently when oceans became more acidic.

  4. Proton pumps are necessary to all cell membranes.

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TLS Online TPP Program

#Question id: 4398

#Unit 3. Fundamental Processes

Which of the following are not found in DNA-binding proteins?

TLS Online TPP Program

#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.

TLS Online TPP Program

#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

TLS Online TPP Program

#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.

TLS Online TPP Program

#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.

TLS Online TPP Program

#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