Splice Sites in Pre-MRNA are Marked by Two Universally Conserved

Question

Splice sites in pre-mRNA are marked by two universally conserved sequences located
A)in the middle of introns.
B)at the ends of exons.
C)at the ends of introns.
D)none of the above

Accepted Answer

Splice sites in pre-mRNA are marked by two universally conserved sequences located at the ends of introns, known as the 5' splice site and 3' splice site. These sequences are recognized by spliceosome machinery during the process of mRNA splicing. Option A is incorrect because introns do not have a middle region, they are located in between exons. Option B is also incorrect because exons do not have a specific sequence marking their ends for splicing.