Question

dna contains instructions for making proteins, but dna is confined to the nucleus. rnas job is to copy instructions from dna and carry them to other parts of the cell.
rna is created in the nucleus by using a section of dna as a template. first, the dnas hydrogen bonds are broken to split, or \unzip,\ the molecule into two strands. then, rna nucleotides are brought in to pair with the dna nucleotides according to the rules of complementary base pairing. but, since rna does not contain thymine, uracil pairs with adenine.
this model shows how rna nucleotides pair with dna nucleotides.

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 thymine, and guanine pairs with dropdown. but rna contains the nitrogenous base uracil instead of dropdown. uracil pairs with dropdown.

Explanation:

1. For the first blank: From the text, "First, the DNA's hydrogen bonds are broken to split, or 'unzip,' the molecule into two strands." So the first blank should be "unzipped" (or "split", but "unzipped" is more precise from the text).
2. For the second blank: In complementary base pairing, adenine (A) pairs with thymine (T) in DNA - RNA pairing here (since RNA is being made from DNA, A in RNA pairs with T in DNA? Wait, no, wait: Wait, the text says "uracil pairs with adenine". Wait, let's re - read the text: "RNA nucleotides are brought in to pair with the DNA nucleotides according to the rules of complementary base pairing. But, since RNA does not contain thymine, uracil pairs with adenine." Also, the standard base pairing: In DNA - RNA transcription, DNA's A pairs with RNA's U, DNA's T pairs with RNA's A, DNA's G pairs with RNA's C, DNA's C pairs with RNA's G. Wait, the question is "____ pairs with thymine". So in RNA - DNA pairing, RNA's adenine (A) pairs with DNA's thymine (T). So the second blank is "adenine" (or "A").
3. For the third blank: Guanine (G) pairs with cytosine (C) (in both DNA - DNA and DNA - RNA pairing for G and C). So "cytosine" (or "C").
4. For the fourth blank: RNA has uracil (U) instead of thymine (T) (as stated in the text: "RNA does not contain thymine, uracil pairs with adenine"). So the fourth blank is "thymine" (or "T").
5. For the fifth blank: Uracil (U) pairs with adenine (A) (from the text: "uracil pairs with adenine"). So "adenine" (or "A").

Let's fill in the blanks step by step:

First, a section of the DNA molecule is unzipped (because the hydrogen bonds are broken to split the DNA into two strands). Then, RNA nucleotides are brought in to pair with the DNA nucleotides. According to the rules of complementary base pairing, adenine (A) pairs with thymine, and guanine pairs with cytosine (C). But RNA contains the nitrogenous base uracil instead of thymine (T). Uracil pairs with adenine (A).

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, \(\boldsymbol{\text{adenine}}\) pairs with thymine, and guanine pairs with \(\boldsymbol{\text{cytosine}}\). But RNA contains the nitrogenous base uracil instead of \(\boldsymbol{\text{thymine}}\). Uracil pairs with \(\boldsymbol{\text{adenine}}\).