AP BIOLOGY

Detailed explanation-1: -Transcription begins when an enzyme called RNA polymerase attaches to the DNA template strand and begins assembling a new chain of nucleotides to produce a complementary RNA strand.

Detailed explanation-2: -RNA polymerase is the main transcription enzyme. Transcription begins when RNA polymerase binds to a promoter sequence near the beginning of a gene (directly or through helper proteins). RNA polymerase uses one of the DNA strands (the template strand) as a template to make a new, complementary RNA molecule.

Detailed explanation-3: -RNA splicing The pre-messenger RNA thus formed contains introns which are not required for protein synthesis. The pre-messenger RNA is chopped up to remove the introns and create messenger RNA (mRNA) in a process called RNA splicing (Figure 5).

Detailed explanation-4: -DNA transcription produces a single-stranded RNA molecule that is complementary to one strand of DNA. Transcription, however, differs from DNA replication in several crucial ways. Unlike a newly formed DNA strand, the RNA strand does not remain hydrogen-bonded to the DNA template strand.