Which of the following is a characteristic of rna splicing in eukaryotes?
a. exon/intron boundaries are typically characterized by a 5' gu splice junction and a 3' ag splice junction.
b. after splicing occurs, the u1, u2, u5, u6 snrnp complex removes remaining exons for degradation.
c. it involves removal of introns from a gene sequence followed by transcription and subsequent splicing of exons.
d. it involves recognition of sequence-specific intron/exon boundary sites by cytoplasmic proteins.

The correct answer is a. Exon/intron boundaries are typically characterized by a 5' GU splice junction and a 3' AG splice junction.

Explanation:

Splicing is the process in which the non-coding introns are removed from the mRNA and only coding sequences remains in mRNA.  

The splicing of introns depends on the recognition of splice site pair. Usually, 5'-GU-3' is 5' splice site and 5'-AG-3' is 3' splice site which makes the boundary of introns/exons and these two nucleotides are important to recognize the introns.

There are some additional conserved sequence at these two splice site which help in recognition of introns. First, a lariate structure is formed when 5'-GU-3' is cleaved and joined to the branch point that is present near 3' slice site. Then 3' splice site is cleaved which releases the intron. Therefore the correct answer is a.

c

explanation:

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.