Question

when transcription occurs in eukaryotic cells, a dna strand is copied to an mrna strand that contains introns and exons. which of the two is needed for the production of proteins, and why?
introns because they are non - coding sequences.
exons because they are non - coding sequences.
exons because they are coding sequences.
introns because they are coding sequences.

Explanation:

Introns are non - coding and are removed during mRNA processing. Exons are the coding parts of mRNA that are joined together. The genetic code in exons is used to synthesize proteins during translation. So, exons are needed for protein production as they carry the coding information.

Answer:

Exons because they are coding sequences.