The classic work of Christian Anfinsen in the 1950s on the enzyme ribonuclease revealed the relation between the amino acid sequence of a protein and its conformation. Ribonuclease is a single polypeptide chain consisting of 124 amino acid residues cross-linked by four disulfide bonds. Anfinsen’s plan was to destroy the three-dimensional structure of the enzyme and to then determine what conditions were required to restore the structure.

The critical observation of Anfinsen that the denatured ribonuclease, freed of urea and b -mercaptoethanol by dialysis;

I. The sulfhydryl groups of the denatured enzyme became reduced by air, and the enzyme spontaneously refolded into a catalytically active form.

II. These experiments showed that the information needed to specify the catalytically active structure of ribonuclease is contained in its amino acid sequence.

III. The 105 wrong pairings have been picturesquely termed “scrambled” ribonuclease.

IV. He found that scrambled ribonuclease spontaneously converted into fully active, native ribonuclease when trace amounts of b -mercaptoethanol were added to an aqueous solution of the protein.

Choose incorrect options;

#Question id: 4070

#Unit 3. Fundamental Processes

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.

#Question id: 4071

#Unit 3. Fundamental Processes

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.

#Question id: 4072

#Unit 3. Fundamental Processes

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.

#Question id: 4073

#Unit 3. Fundamental Processes

The expression of which gene(s) is (are) regulated by promoter proximal pausing?

#Question id: 4074

#Unit 3. Fundamental Processes

The promoter sequences of RNA polymerase III-transcribed genes are located

#Question id: 4075

#Unit 3. Fundamental Processes

Pre-mRNA molecules

a. exist as free RNA molecules in eukaryotic cells.

b. are associated with an abundant set of nuclear proteins.

c. are mostly located in the cytoplasm.

d. are located in the nucleus.