Cellulose microfibrils have an ordered structure and are synthesized at the plasma membrane, given characteristics of microfibrils;

a) Each microfibril is composed of an estimated 18 parallel chains of (1,4)-linked β-D-glucose chains tightly bonded to each other to form a crystalline microfibril

b) Microfibrils have hydrophilic surfaces, populated by polar –OH groups extending from theplane of the sugar rings

c) Microfibrils have hydrophobic surfaces, populated by nonpolar C–H groups populating thesides of stacked glucose chains

 d) microfibril important for enzymatic attack by microbial cellulases, which dock onto the hydrophobic surface and remove one glucan chain at a time

Which of the following from given characterstics of microfibrils is incorrect?

#Question id: 935

#Unit 1. Molecules and their Interaction Relevant to Biology

Microorganisms capable of fixing nitrogen into a form usable by animals obtain the energy for this process from ________.

#Question id: 10488

#Unit 6. System Physiology – Plant

Blue light activates a proton pump at the guard cell plasma membrane. The relationship between proton pumping at the guard cell plasma membrane and stomatal opening is evident from the observations that;

 a.) Orthovandate inhibits the fusicoccin-stimulated opening

 b.) fusicoccin stimulates both proton extrusion from guard cell protoplasts and stomatal opening

 c.) CCCP inhibits the fusicoccin-stimulated opening

 d.) CCCP, a proton ionophore that makes the plasma membrane highly permeable to protons resulting stomatal opening

 Which one of the following observation from the above statements should  be correct?

#Question id: 17656

#Unit 7. System Physiology – Animal

#Question id: 30102

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following would NOT be expected to contribute to hyperuricemia (gout)?

#Question id: 805

#Unit 1. Molecules and their Interaction Relevant to Biology

miRNAs are encoded in the genome as segments of longer transcripts. Their characteristic structure helps identify them and predict the target genes they might regulate. Which of the following are the characteristic features of these small RNA molecules?

I. The functional form of an miRNA is typically 21 or 22 nucleotides (it can vary from 19 to 25 nucleotides).

II. The first cleavage liberates the stem-loop, called the pre-miRNA; the second generates the mature miRNA from the pre-miRNA.

III. The pre-miRNAs can be encoded by any part of a transcript: that is, they might fall within coding regions, within leader regions, or within Introns.

IV. The base pairing between miRNA and target RNA is initiated by interactions of so-called seed residues—the sequence between bases 2 and 9 of the 22-nucleotide miRNA.