Question

The process of transcription and splicing of mRNA is shown above. What statement accurately describes these two steps? A) Transcription and splicing only occur in eukaryotic cells. Transcription and splicing both occur in the nucleus. B) Transcription and splicing only occur in prokaryotic cells. Transcription and splicing both occur in the cytosol. C) Transcription occurs only in prokaryotic cells in the cytosol while splicing occurs only in eukaryotic cell sin the nucleus. D) Transcription and splicing only occur in eukaryotic cells. Transcription occurs in the nucleus while splicing occurs in the cytosol.

Answer 1

Answer:

A

Explanation:

Transcription is the first process of protein synthesis which occurs in the nucleus of eukaryotic cells. It involves making a complementary strand of mRNA from a DNA template. The encoded information in the DNA is transferred to a mRNA which acts as a conveyer that carries the information out of the nucleus into the cytoplasm for translation. However, when an mRNA is first made in the nucleus of an eukaryotic cell, it is considered a pre-mRNA.

Eukaryotes undergo the processing of the pre-mRNA immediately after transcription in the nucleus, before it is ready to leave the nucleus for translation. The genes of an eukaryote contains parts that are expressed as RNA products (actual coding regions), called EXONS and other parts that are not expressed (junk sequences) called INTRONS. These non-coding regions are removed from the gene and the adjacent ends of the exons are joined together by SPLICEOSOMES (located in the nucleus), in a process called mRNA SPLICING.

These processes of transcription and splicing (both in the nucleus) is a characteristics of eukaryotes as prokaryotes don't process mRNA. The transcription of prokaryotes is coupled with translation in the cytosol, hence, they can't have introns as there is no time and space for splicing (intron removal) to occur.

Answer 2

Answer: The answer is D

Explanation: