Chapter 12, Problem 24A

Solution

To write:

A sentence that connects the two vocabulary terms, intron and exon.

Introduction:

According to central dogma, the information flows from DNA to RNA to proteins. The process of synthesis of RNA is accomplished through a process called transcription. Transcription is a process of conversion of DNA into RNA. This process mainly occurs in the nucleus in eukaryotes while in prokaryotes, it occurs in cytoplasm.

A sentence that joins the vocabulary terms intron and exon is “The introns are removed and exons are joined together during RNA splicing”.

Steps of transcription

Initiation is the beginning of transcription. When the enzyme RNA polymerase binds to the promoter region, it initiates and signals the DNA to unwind. The unwinding of DNA is done by DNA helicase enzyme. The enzyme RNA polymerase is now ready to make a strand of mRNA with a complementary sequence of bases.

Elongation refers to the addition of nucleotides to the mRNA strand. The enzyme RNA polymerase reads the DNA strand and builds the mRNA molecule, using complementary base pairs. During this process, an adenine A in the DNA binds to an uracil U in the RNA.

Termination refers to the ending of transcription, and it happens when RNA polymerase reaches a termination sequence. A release factor detaches the DNA. The mRNA strand is now complete.

Transcription in prokaryotes is a bit complex than that of eukaryotes. In eukaryotes, RNA splicing occurs by which, pre-mRNA is made into mature mRNA, by removal of introns and joining together of exons.