Answer:
The miRNAs act as post-transcriptional silencers, as they are similar to specific mRNAs and regulate their stability and translation. They are small endogenous non-coding ribonucleic acid (RNA) molecules, with about 22 nucleotides, which act as regulators of gene expression in plants and animals, at the post-transcriptional level through the cleavage of a target messenger RNA (mRNA) or repression of translation.
In general, most miRNA genes are transcribed by RNA polymerase II in the nucleus in primary miRNAs (pri-miRNAs). Individually, a pri-miRNA can produce a single miRNA or contain groups of two or more miRNAs that are processed from a common primary transcript. These long pri-miRNA are cleaved by a complex comprising the double-stranded RNAse III enzyme (DROSHA) and its essential cofactor, the binding protein DGCR8 (DiGeorge Syndrome Critical Region 8 protein) in mammals. DROSHA contains two domains of RNAse III, each of which cleaves a strand of the RNA resulting in the precursor microRNA (pre-miRNA) with about 70 base pairs, which contains a double-stranded stretch and a single-stranded loop, forming a structure in clamp. The pre-miRNA is exported to the cytoplasm by the protein exportin-5 (XPO-5), where it is cleaved by DICER1, an RNAse III that assesses the 3 'and 5' ends of the pre-miRNA, generating a mature miRNA with about 22 nucleotides. The processing of pre-miRNA by Dicer promotes the unfolding of the RNA duplex in the form of a clamp. The position in the formation of the clamp can also influence the choice of tape.
Explanation:
<em>G1, S and G2 phases are all cumulatively referred to as interphase involving the growth of a cell and the replication of its DNA. Initially in G1 phase, the cell grows physically and increases the volume of both protein and organelles. In S phase, the cell copies its DNA to produce two sister chromatids and replicates its nucleosomes. Finally, G2 phase involves further cell growth and organisation of cellular contents. The S phase of a cell cycle occurs during interphase, before mitosis or meiosis, and is responsible for the synthesis or replication of DNA. In this way, the genetic material of a cell is doubled before it enters mitosis or meiosis, allowing there to be enough DNA to be split into daughter cells. The S phase only begins when the cell has passed the G1 checkpoint and has grown enough to contain double the DNA. S phase is halted by a protein called p16 until this happens.</em>
True. Since electron microscopes use electrons instead of light, it can magnify up to 500,000 times of it’s actual size.
Photosynthesis is carried out in the chloroplasts which contain the green pigment chlorophyll. Chlorophyll is what gives plants their characteristic color and it works by capturing the energy that is in the sunlight that strikes the plant.
Photosynthesis is important to life on Earth because grass uses photosnthesis to produce glucose, which is used within the grass for growth<span>. Subsequently, organisms that consume the grass obtain energy and so on. Therefore, photosynthesis is the process through which energy enters an ecosystem.</span>
