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: 4969

#Unit 11. Evolution and Behavior

The snowball Earth hypothesis provides a possible explanation for the

#Question id: 4966

#Unit 11. Evolution and Behavior

If it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.2-billion-year-old stromatolites, then within such microfossils, one should be surprised to observe evidence of:

I. double-stranded DNA

II. a nuclear envelope

III. a nucleoid

IV. a nucleolus

V. nucleic acids

#Question id: 4960

#Unit 11. Evolution and Behavior

Letʹs say that a hypothetical submersible robot was used to collect samples of sedimentary rock from the sea floor along the section illustrated. The robot moved back and forth along the transect, collecting first from site A, then site III, then site B, then site II, and lastly site D. Assuming that sedimentation has occurred at a constant rate along the transect over the past million years, rearrange the sites mentioned above on the basis of the thickness of the sediments overlying the igneous rock, from thickest to thinnest.

#Question id: 4959

#Unit 11. Evolution and Behavior

If a fossil is encased in a stratum of sedimentary rock without any strata of igneous rock (e.g., lava, volcanic ash) nearby, then it should be

#Question id: 4564

#Unit 11. Evolution and Behavior

Who would have proposed that the boundaries between each stratum mark the occurrence of different localized floods?

#Question id: 4565

#Unit 11. Evolution and Behavior

Darwinʹs mechanism of natural selection required long time spans in order to modify species. From whom did Darwin get the concept of Earthʹs ancient age?