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 most probable future changes in the global climate are:
- Global warming;
If the levels of CO2 and methane increase enough in the atmosphere to be able to intensify the Greenhouse effect, than some portion of the ice on the planet will melt because of the rising temperatures, thus lifting up the sea level, creating more unpredictable weather with larger and stronger storms, but also making the mainland much drier. This would be a scenario if the continents are arranged like they are now, but if there isn't a sufficient mass of land on and around the poles, than all of the ice will melt and the sea levels will rise so much that the planet will come in the ''water planet'' scenario, and it will have wet tropical climate pretty much everywhere on the planet.
- Ice Age;
If there's a disruption in the warm ocean streams and some of them disappear, or the levels of nitrogen or oxygen increase in the atmosphere, the Earth will start to cool off, thus coming to a situation of an Ice Age. In this kind of situation, there will be large ice sheets on and around the poles that are stretching much further towards the lower latitudes, as well as mountains all over the world that are covered in snow and shaped by glaciers.
Answer:D) The starch adapted flies and maltose adapted flies are not different species but a reproductive barrier is forming between the two populations
Explanation: differences have accumulated within the populations to isolate them reproductively. The flies have chosen to mate with those like them.
It's about the size of our sun and called a Main sequence star
Answer:
The cerebellum controls your balance, coordination and your speech, making you balance in muscular activity
It's C
