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.

#Question id: 9589

#Unit 6. System Physiology – Plant

The physical mechanism by which excitation energy is conveyed from the chlorophyll that absorbs the light to the reaction centre, By this mechanism the excitation energy is transferred from one molecule to another by a nonradioactive process, this mechanism is known as

#Question id: 9595

#Unit 6. System Physiology – Plant

The process is that the absorbed photon causes an electron rearrangement in the reaction centre chlorophyll, followed by an electron transfer process in which part of the energy in the photon is captured in the form of

#Question id: 9596

#Unit 6. System Physiology – Plant

The reaction centre chlorophyll is transiently in an oxidized state after losing an electron and before being re-reduced by its electron donor, what characteristics has been shown by chlorophylls in an oxidized state?

#Question id: 9599

#Unit 6. System Physiology – Plant

The primary donor of PSI, P700, is a dimer of chlorophyll a molecules, in primary donor chlorophyll, additional chlorophylls molecules such as

#Question id: 10127

#Unit 6. System Physiology – Plant

In higher plants, the multi-subunit protein supercomplex has two complete reaction centers and some antenna complexes. The core of the reaction center consists of two membrane proteins known as D1 and D2, Which contained a multi-subunit protein supercomplexes;

#Question id: 10129

#Unit 6. System Physiology – Plant

Oxidation of water to form molecular oxygen is very difficult: The photosynthetic oxygen-evolving complex is the only known biochemical system that carries out this reaction which essential cofactor are involved in the water-oxidizing process?