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.
B. bacteria that convert ammonia into nitrites and nitrates are found in the soil
This statement best demonstrates a way that the geo-sphere is involved in the nitrogen cycle.
A nitrogen cycle is defined as the movement of nitrogen between the atmosphere, biosphere, and geo-sphere in different forms. Ammonia is converted to nitrates by nitrifying bacteria in the soil. Then the plants absorb these nitrates from the soil and use these to build up proteins.
Answer:
(C). white blood cell production
Explanation:
CSFs (colony stimulating factors) are glycoproteins that activate intracelluar pathways and promote proliferation of hemopoietic stem cell to form immune cells (white blood cells).
CSFs are released in response to infection and interacts with blood stem cells to produce new immune cells. These resulting new immune cells create an army of cells to fight against the infection and provide immunity.
Thus, the correct answer is option (C).
Skeletal, smooth, and carbiac. Carbiac makes up the heart.
It tells us how they might have looked weighed, ate and tall the were
