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:
The entry of food into the stomach.
Explanation:
Gastric secretion is triggered by the act of eating which is called as reflex phase and the entry of food into the stomach called a gastric phase. The entry of the food particles into the small intestine also helps to control the secretion of gastric called an intestinal phase.
The secreted fluid in the small intestine contains some ions, acids, etc such as pepsinogen, intrinsic factor, bicarbonate, hydrochloric acid, and mucus. The reflex phase or cephalic phase helps to stimulate parasympathetic neurons that release acetylcholine chemical, then it produces the higher secretion of gastric juice.
Question 8-
(a) move out of the cell
(b) cell would shrink
(c) hypertonic
Queston 9-
(a) move into the cell
(b) cell would swell
(c) hypotonic
There is not any options but the parts of Lac Operon is:
Promoter
Repressor
Operator
Genes
Hope this helps!
Answer:
Warm front
Explanation:
A warm front is the transition zone of the replacement of a cold air mass by a warm air mass. The pressure centers of warm fronts are usually low and the pressure read by a barometer will decrease due to an incoming warm front
The general direction of motion of warm fronts is from southwest to northeast with warmer and moist air behind the warm front than air into which the front flows. Therefore, warm fronts normally results in moderate precipitation or rainfall or snow.
