Meristematic tissue have the ability to
divide themselves. It is the primary site for cell division and cell
differentiation. It produces the new cells and are called growing tissue in
plants. The new cells may or may not divide. It is the source of the regenerative
potential of the plant.
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Cancerous cells can originate anywhere in the
body and can spread into or invade adjoining tissues. It keeps growing and dividing
relentlessly to form lumps. It can also break off and travel to distant
tissues. Cancer cells rejects signals from other cells.</span>
Translocation has taken place, you can tell by the rearrangement of nonhomologous chromosomes.
Answer:
(C) Aminoacyl-tRNA synthetases have an additional active site that binds to non-cognate tRNAs. The tRNAs that bind to this second active are hydrolyzed and released from the enzyme.
Explanation:
In case of translation, proof reading is done by aminoacyl-tRNA synthetases only. Aminoacyl-tRNA synthetases have two mechanisms to avoid error during translation which are mentioned as under:
<u>(1) Chemical proof reading:</u> Incorrect amino acids rather than being hydrolyzed in catalytic pocket get hydrolyzed in editing pocket and thus they hardly get attached to tRNA.
For example: For distinguishing similar amino acids like isoleucine and valine, isoleucyl-tRNA synthetase uses a second active site which is meant for only valine not for isoleucine. In this particular site, valine which had entered the enzyme is cleaved away with the help of editing reaction after which the enzyme is well prepared to process isoleucine which is the correct amino acid for this enzyme.
<u>(2) Kinetic proof reading: </u>Even if an incorrect amino acid has entered a particular aminoacyl-tRNA synthetase, it does not cause appropriate conformational change in the enzyme because of which the incorrect amino acid loosens from the enzyme and does not get incorporated.
Note: In this example, only chemical proof reading is mentioned not kinetic proof reading.
The ECT treatment includes electric stimulus used to produce a generalized seizure. Professionals using electroconvulsive shock therapy (ECT) for patients suffering from severe depression have shown that the memory processes of consolidation may take years to return.
