AP BIOLOGY

THE MOLECULAR BASIS OF INHERITANCE

DNA MAKES RNA MAKES PROTEIN

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
What enzyme transcribes DNA into mRNA?
A
DNA polymerase
B
RNA polymerase
C
helicase
D
rRNA
Explanation: 

Detailed explanation-1: -During transcription, the DNA of a gene serves as a template for complementary base-pairing, and an enzyme called RNA polymerase II catalyzes the formation of a pre-mRNA molecule, which is then processed to form mature mRNA (Figure 1).

Detailed explanation-2: -Although the mRNA contains the same information, it is not an identical copy of the DNA segment, because its sequence is complementary to the DNA template. Transcription is carried out by an enzyme called RNA polymerase and a number of accessory proteins called transcription factors.

Detailed explanation-3: -Transcription is the first step in gene expression. It involves copying a gene’s DNA sequence to make an RNA molecule. Transcription is performed by enzymes called RNA polymerases, which link nucleotides to form an RNA strand (using a DNA strand as a template).

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