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.
Answer:
Option (D)
Explanation:
The entropy is usually defined as the measure of the total thermal energy of a system per unit temperature. This amount of energy is used in performing valuable work. In simple words, it can be said that entropy is related to the disorder or degree of randomness of a particular system. This entropy concept gives proper information regarding the direction along which natural change occurs and is frequently observed in many present-day events.
Thus, the correct answer is option (D).
Answer:
b
Explanation:
the water gave the plant a drink
Each plant contains a branched system of tubes called xylem, which is responsible for water transport from the roots<span> (where it is taken up) to the leaves (where it is used in </span>photosynthesis<span>).
hope this answers your question</span>
<u>Answer:</u>
- few nutrients
- high pressure
- low temperatures
<u>Explanation:</u>
1. Few nutrients: open-ocean zone is located way far from the land, which is the main source of the essential nutrients.
2. High pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.
3. Ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface.
4. Varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.
5. Low temperatures: the temperature of open-ocean zone ranges from a low of -2°C to an average of 17°C.
