Oxygen-Evolving Organisms Have two Photosystems that Operate in Series, explain by emerson that is the Photosystem I preferentially absorbs far-red light of wavelengths greater than 680 nm; photosystem II preferentially absorbs red light of 680 nm and is driven very poorly by far-red light; Another difference between the photosystems is that,

a.) Photosystem I produces a strong reductant, capable of reducing NADP+, and a weak oxidant

b.) Photosystem I produces a very strong oxidant, capable of oxidizing water, and a weaker reductant than the one produced by photosystem II

c.) Photosystem II produces a strong reductant, capable of reducing NADP+, and a weak oxidant

d.) Photosystem II produces a very strong oxidant, capable of oxidizing water, and a weaker reductant than the one produced by photosystem I

Which statements would be CORRECT?

#Question id: 911

#Unit 1. Molecules and their Interaction Relevant to Biology

The correct order for molecular chaperone–mediated protein folding is:

I – exchange of ATP for ADP on chaperone

II – chaperone undergoes conformational change, which affects protein folding

III – chaperone binds to exposed hydrophobic residues on unfolded protein

IV – folded protein is released

#Question id: 910

#Unit 1. Molecules and their Interaction Relevant to Biology

Experiments on denaturation and renaturation after the reduction and reoxidation of the —S—S— bonds in the enzyme ribonuclease (RNase) have shown that:

#Question id: 909

#Unit 1. Molecules and their Interaction Relevant to Biology

Most proteins denature at both high and low pH. At high pH, the ionization of internal tyrosines is thought to be the main destabilizing influence, whereas at low pH, the protonation of buried histidines. A titration curve for the unfolding of the enzyme ribonuclease is shown in Figure. Given the relation between the titration curves for protein unfolding and histidine protonation, which of the following conclusion can be drawn correctly?

A. The sharp transition in graph indicates a highly cooperative process; when the protein starts to unfold, it completes the process rapidly

B. The sharp transition in graph indicates a highly noncooperative process

C. Several buried histidines can ionize when the chain starts to unfold, so that when one goes, they all go together due to cooperative behaviour of protein folding

D. Buried histidine (pK of 4 in this example) becomes accessible to solvent, its pK will shift toward its normal value of 6, significantly steepening its titration curve.

#Question id: 908

#Unit 1. Molecules and their Interaction Relevant to Biology

Molecular chaperones are a class of proteins that play a role

#Question id: 907

#Unit 1. Molecules and their Interaction Relevant to Biology

Thermodynamics of protein folding is depicted as a free energy vs folding process:

Choose the correct match for regions mentioned in the figure

#Question id: 906

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following is least likely to result in protein denaturation?