Well I do know the answer to question #5 is temperature
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:
both contain genetic information
Answer:
gDNA = "genomic DNA" and cDNA = "complementary DNA." cDNA is classically associated with being reverse transcribed either from all extracted RNA from a tissue or cell (total RNA) including (in eukaryotes) pre-mRNA, ribosomal RNA, tRNA, snoRNA, miRNA and mRNA, etc.) while cDNA obtained only from reverse transcription of the mRNA (expressed eukaryotic cytosolic mRNA) fraction (e.g., by poly[dT]n and random priming) is complementary DNA (cDNA) made from what is called the "transcriptome." Eukaryotes have introns and exons in the gDNA, while prokaryotes do not. So eukaryotic cDNA reverse transcribed from mRNA lacks introns. Prokaryotic-derived cDNA is always complementary to prokaryotic RNA and gDNA (so is always necessary to have a good DNase treatment prior to gene expression analysis by e.g., qPCR for prokaryotic transcriptome work)...
