A nucleotide of DNA may contain
A. ribose, uracil,and a phosphate group
B.deoxyribose, uracil, and a phosphate group
C.deoxyribose, thymine, and a phosphate group
D.ribose, thymine, and a phosphate group
The correct answer and explanation is:
Correct Answer: C. deoxyribose, thymine, and a phosphate group
A nucleotide is the basic building block of nucleic acids such as DNA and RNA. Each nucleotide is made up of three components: a sugar molecule, a phosphate group, and a nitrogenous base. In the case of DNA, the sugar is deoxyribose, the phosphate group remains the same across all nucleotides, and the nitrogenous base can be adenine, guanine, cytosine, or thymine.
DNA differs from RNA in several key structural aspects. DNA uses deoxyribose as its sugar, whereas RNA uses ribose. This small difference changes the chemical stability of the molecule. DNA is more stable than RNA because deoxyribose lacks one oxygen atom that ribose has. Another major difference is the type of nitrogenous bases. DNA contains thymine, while RNA contains uracil in place of thymine.
Let us break down the answer choices:
- A. ribose, uracil, and a phosphate group: This describes a nucleotide of RNA, not DNA.
- B. deoxyribose, uracil, and a phosphate group: This is incorrect because uracil is not found in DNA.
- C. deoxyribose, thymine, and a phosphate group: This is the correct combination for a DNA nucleotide.
- D. ribose, thymine, and a phosphate group: This is incorrect because thymine is not used in RNA, and ribose is not used in DNA.
Therefore, the correct structure of a DNA nucleotide includes deoxyribose as the sugar, thymine as the nitrogenous base, and a phosphate group. These nucleotides link together to form the long chains of DNA through phosphate-sugar bonds, forming the backbone of the double helix structure. The sequence of nitrogenous bases carries genetic information.