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.
Exoskeleton
Exoskeleton is a evolutionary innovation. This is operated by muscles attached to it and acts as an armor. Other than support this is an adaptive mechanism to provide protection against predators. In vertebrates, it is considered as the dermal bone that developed via membranous ossification. Fishes retained their exoskeleton in the form of their scales. However, in some organisms terrestrial evolution allows the loss of exoskeleton and formed a more mobile endoskeleton,
Answer:
D) Yellowstone Hot Spot-North American Plate
Explanation:
Answer:
The correct answer would be - wildtype.
Explanation:
Let assume there are four genes which are :
A-B-C-D
In mutant first, the genotype would be:---a-b-C-D
In the mutant second, the genotype would be:--A-B-c-d
If both of these genotypes are crossed with each other, the recessive genes a, b of mutant first is dominated and masked the expression by the dominant genes present in the mutant second.
Similarly, the recessive genes of the mutant second are dominated and masked expression by the dominant genes of mutant first. This is possible only due to different genes are present in mutants.
Thus, the correct answer is - The correct answer would be - wildtype.
