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.
As the leaf surface area decreases ; Number of leaves increase inmost plants.
As the leaf surface area increases, the rate of transpiration increases as well because leaves with large surface areas have bigger stomata. also the smaller the leave surface area of a plant/tree the denser the leaves the plants/tree will have.
Trees with tiny leaves tend to have a lot of leaves because of the decrease transpiration rate occurring in the leaves of the plants .
Hence we can conclude that what generally happens to the number of leaves as leaf surface area decrease is number of leaves increases in most plants.
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Not to be too picky, but the question ought to say a positively charge ion rather than atom.
I will assume that is what you mean. An ion, using ordinary means, will be positive if it loses electrons (which are negative).
An ion can never gain protons. Left alone, the nucleus will remain unchanged for the rest of eternity. D is wrong.
C is wrong. If electrons are gained, the ion will go negative.
B is wrong for the same reason D is. An ion can't gain protons and it can't lose them.
A is the answer.
Contour: Gives the bird its stream line shape.
<span>Down feathers: Keeps the bird warm.</span>
The answer is choice B.
Nondisjunction happens when the chromosomes don't separate correctly during meiosis, which can result in an extra copy of certain chromosome.
I hope this helped a little bit.
