Which of the following statements regarding DNA is FALSE?
A.
DNA contains the sugar deoxyribose
B.
DNA contains the nitrogenous base uracil
C.
DNA molecule can include four different nucleotides
The Correct Answer and Explanation is :
The false statement is:
B. DNA contains the nitrogenous base uracil.
Explanation:
DNA (Deoxyribonucleic Acid) is the hereditary material in all living organisms. It is composed of nucleotides, each consisting of three components: a phosphate group, a sugar molecule (deoxyribose), and a nitrogenous base. The nitrogenous bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).
Why is Statement B False?
DNA does not contain uracil (U). Instead, it contains thymine (T). Uracil is found in RNA (Ribonucleic Acid), which differs from DNA in a few key ways:
- RNA contains ribose instead of deoxyribose.
- RNA is usually single-stranded, whereas DNA is double-stranded.
- RNA uses uracil (U) instead of thymine (T) to pair with adenine (A).
Thus, the presence of uracil in DNA is incorrect, making statement B false.
Why the Other Statements Are True:
A. DNA contains the sugar deoxyribose → True
DNA’s sugar is deoxyribose, which lacks an oxygen atom on the second carbon (hence the name “deoxy”). This distinguishes it from RNA, which has ribose.
C. DNA molecule can include four different nucleotides → True
DNA is made of four nucleotides, each containing one of the four nitrogenous bases: Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). These nucleotides form the genetic code of life.
Now, I will generate an image illustrating the structure of DNA, including its sugar-phosphate backbone and nitrogenous bases.
Here is a detailed 3D rendering of a DNA double helix structure, highlighting the sugar-phosphate backbone and nucleotide base pairs (A-T and C-G). The image does not include uracil, reinforcing that uracil is found in RNA, not DNA. Let me know if you need any modifications!