Answer:A, B, D, E
Explanation:i just did it on usatestprep, trust
Answer:
the time I spent on a trip was really fun to work and work in your first place and the way
Answer: C. Positive feedback mechanisms are overwhelmed.
Explanation:
Homeostasis, is the maintenance of a normal internal environment, in the face of external and internal disturbances, so that the functions of cells and systems of the body are preserved. This is accomplished primarily through feedback systems, so when a system is disturbed, a diversity of local responses, systemic reflexes (rapid reactions and automatic stimuli) and long-term adjustments are activated to bring the system back to its normal equilibrium point.
Most systems are controlled by negative feedback mechanisms, with the controlled variable being able to "turn off" its release, in the same way as a thermostat controls the temperature of a room. So, in this context, too much positive feedback would be related to harmful effects, such as homeostatic imbalance.
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:
Viruses use their own catabolic enzymes.
Explanation:
Viruses are the infective particles present in the environment which encloses their genetic material which could be wither RNA or DNA enclosed in the protein coat.
The protein coat is made of the capsomers which are arranged in the tubular structure forming capsid. The viruses do not contain the metabolic machinery of their own that is the reason that they do not have replication or transcription or translation machinery. For this they are dependent on the host organisms as they use their machinery.
Thus, the selected option is correct.