AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

GENE MUTATION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which part of mRNA is eliminated during RNA processing?
A
introns
B
exons
C
Poly-A tail
D
splicosomes
Explanation: 

Detailed explanation-1: -In RNA splicing, specific parts of the pre-mRNA, called introns are recognized and removed by a protein-and-RNA complex called the spliceosome. Introns can be viewed as “junk” sequences that must be cut out so the “good parts version” of the RNA molecule can be assembled.

Detailed explanation-2: -Introns are removed from the pre-mRNA by the activity of a complex called the spliceosome. The spliceosome is made up of proteins and small nuclear RNAs (snRNAs) that associate to form protein-RNA enzymes called small nuclear ribonucleoproteins or snRNPs (pronounced SNURPS).

Detailed explanation-3: -During the process of splicing, introns are removed from the pre-mRNA by the spliceosome and exons are spliced back together. If the introns are not removed, the RNA would be translated into a nonfunctional protein. Splicing occurs in the nucleus before the RNA migrates to the cytoplasm.

Detailed explanation-4: -Intron Processing Introns are removed and degraded while the pre-mRNA is still in the nucleus. Splicing occurs by a sequence-specific mechanism that ensures introns will be removed and exons rejoined with the accuracy and precision of a single nucleotide.

Detailed explanation-5: -Introns are removed from primary transcripts by cleavage at conserved sequences called splice sites. These sites are found at the 5′ and 3′ ends of introns. Most commonly, the RNA sequence that is removed begins with the dinucleotide GU at its 5′ end, and ends with AG at its 3′ end.

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