Question

model shows how rna nucleotides pair with dna nucleotides.
image of dna - rna pairing with nitrogenous bases: a - adenine, t - thymine, g - guanine, c - cytosine, u - uracil
complete the paragraph to summarize how an rna molecule is created.
first, a section of the dna molecule is dropdown. then, rna nucleotides are brought in to pair with the dna nucleotides. according to the rules of complementary base pairing, dropdown pairs with adenine, and cytosine pairs with dropdown. but rna contains the nitrogenous base uracil instead of dropdown. uracil pairs with dropdown.

Explanation:

To solve this, we recall the process of transcription (RNA synthesis) and complementary base pairing rules:

1. First blank: During transcription, a section of DNA is "unzipped" (separated) to expose the bases for RNA synthesis.
2. Second blank: In RNA - DNA base pairing, uracil (U) pairs with adenine (A) of DNA (since RNA has U instead of T).
3. Third blank: Cytosine (C) pairs with guanine (G) (this is a standard base - pairing rule: C - G).
4. Fourth blank: RNA has uracil (U) instead of thymine (T) (T is present in DNA, U in RNA).
5. Fifth blank: Uracil (U) pairs with adenine (A) of DNA.

Answer:

First, a section of the DNA molecule is \(\boldsymbol{\text{unzipped}}\). Then, RNA nucleotides are brought in to pair with the DNA nucleotides. According to the rules of complementary base pairing, \(\boldsymbol{\text{uracil}}\) pairs with adenine, and cytosine pairs with \(\boldsymbol{\text{guanine}}\). But RNA contains the nitrogenous base uracil instead of \(\boldsymbol{\text{thymine}}\). Uracil pairs with \(\boldsymbol{\text{adenine}}\).