Final answer:
The statement is false; uracil is found in RNA, not DNA. DNA contains thymine as one of its four nitrogenous bases, whereas RNA contains uracil, which pairs with adenine during protein synthesis.
Step-by-step explanation:
The claim that only DNA molecules contain the nitrogen base called uracil is false. The nitrogenous base uracil is not found in DNA but is one of the four bases in RNA. RNA nucleotides include adenine, cytosine, guanine, and uracil, whereas DNA nucleotides have adenine, cytosine, guanine, and thymine. Uracil in RNA serves a role similar to that of thymine in DNA, pairing with adenine during the process of protein synthesis. While both uracil and thymine contain a single-ring structure, making them pyrimidines, uracil is structurally different as it is the unmethylated form of thymine.
Nucleic acids, such as DNA and RNA, vary in their bases: DNA has adenine (A), guanine (G), cytosine (C), and thymine (T), whereas RNA contains adenine (A), guanine (G), cytosine (C), and uracil (U). Additionally, whereas DNA is arranged as a double helix, RNA is typically single-stranded and comes in several forms such as mRNA, tRNA, and rRNA, each serving different functions in protein synthesis.