LABORATORY REVIEW
MOLECULAR BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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stays in the nucleus
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is processed to remove exons from the raw transcript
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is processed to insert exons into the raw transcript
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is processed to add a 5 prime cap and a 3 prime tail
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is processed to add a 3 prime cap and a 5 prime tail
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Detailed explanation-1: -The group at the beginning (5’ end) is called a cap, while the group at the end (3’ end) is called a tail. Both the cap and the tail protect the transcript and help it get exported from the nucleus and translated on the ribosomes (protein-making “machines") found in the cytosol 1start superscript, 1, end superscript.
Detailed explanation-2: -5′ Capping While the pre-mRNA is still being synthesized, a 7-methylguanosine cap is added to the 5′ end of the growing transcript by a 5′-to-5′ phosphate linkage. This moiety protects the nascent mRNA from degradation.
Detailed explanation-3: -In eukaryotes, the 5′ cap (cap-0), found on the 5′ end of an mRNA molecule, consists of a guanine nucleotide connected to mRNA via an unusual 5′ to 5′ triphosphate linkage. This guanosine is methylated on the 7 position directly after capping in vivo by a methyltransferase.
Detailed explanation-4: -5’ End Capping At the end of transcription, the 5’ end of the RNA transcript contains a free triphosphate group since it was the first incorporated nucleotide in the chain. The capping process replaces the triphosphate group with another structure called the “cap". The cap is added by the enzyme guanyl transferase.