The mechanisms that regulate the loading of sucrose from the apoplast to the sieve elements by the sucrose–H+ symporter await characterization. Possible regulatory factors include the following:

a) The solute potential or, more likely, the turgor pressure of the sieve elements

b) Sucrose concentration in the apoplast

c) The available number of symporter protein molecules

Which one of the mechanism that involve to regulate the loading of sucrose?

#Question id: 674

#Unit 1. Structure and Function of Biomolecules

Proline is not often found in a-helices of proteins because it

#Question id: 1520

#Unit 1. Structure and Function of Biomolecules

Following statements are regarding to enzymatic processing of benzo(a)pyrene to a more potent mutagen and carcinogen.

A. Liver enzymes, particularly P-450 enzymes, modify benzo(a)pyrene in a series of reactions, producing 7,8-diol-9,10-epoxide, a highly potent mutagenic species that reacts with DNA primarily at the N2 atom of a guanine base.

B. The adduct, (+)-trans-anti-B(a)P-N2-dG, causes polymerase to insert an A rather than a C opposite the modified G base. Next time the DNA is replicated, a T will be inserted opposite the A, and the mutation will be complete.

C. Potent mutagen majorly causes conversion of guanine (G) to thymine (T) bases, a transition mutation.

D. When this potent mutagen applied to cultured bronchial epithelial cells, activated benzo(a)pyrene induces many mutations, including activating mutations at codons 175, 248, and 273 of the p53 gene.

Which of the following statements are correct?

#Question id: 835

#Unit 1. Structure and Function of Biomolecules

The minor clefts and gullies on the sides of the funnel that will be false energy minima, it represents,

#Question id: 837

#Unit 1. Structure and Function of Biomolecules

Increasing order of free energy in unfolded to folded conformation of the proteins, the correct order is,

#Question id: 2636

#Unit 1. Structure and Function of Biomolecules

Which of the following events occur when E. coli is starved for tryptophan?

I.  The ribosome translates leader peptide completely

II. Transcription reads through attenuator into trp EDCBA

III. Tryptophanyl tRNA is not formed

IV. A stem loop structure involving regions 3 and 4 is formed at attenuator site

#Question id: 18219

#Unit 1. Structure and Function of Biomolecules