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.
In cellular respiration is the process of extracting energy in the form of ATP from the glucose in the food you eat. In stage one glucose is broken down in the cytoplasm of the cell in a process call glycolysis. In stage two the pyruvate molecules are transported into the mitochondria
DNA mutations that actually originate in the gametes is mainly responsible for genetic biodiversity existing in modern organisms. The term biodiversity actually refers to the variety as well as variability of life that is found on the planet earth. his variety can be seen between species, the ecosystem and within the species.<span />
Below are the choices, the answer is no. 3:
1) The virus was descended from a common ancestor of bird, pig, and human flu viruses.
2) The infected individuals happened to be infected with all three virus types.
3)Related viruses can undergo genetic recombination if the RNA genomes mix andmatch during viral assembly.
4)The human was likely infected with various bacterial strains that contained all three<span>RNA viruses.</span>
