Q
QuestionBiochemistry

The "backbone" of the DNA molecule is made up of two alternating components. What are these called?
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Answer

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Step 1:
: Understand the question and recall relevant information

The backbone of a DNA molecule is made up of repeating units known as nucleotides. Each nucleotide consists of a sugar molecule, a phosphate group, and a nitrogenous base. There are four types of nitrogenous bases in DNA: adenine (A), guanine (G), cytosine (C), and thymine (T). The sugar and phosphate groups form the sugar-phosphate backbone of the DNA molecule.

Step 2:
: Identify the components of the DNA backbone

The backbone of a DNA molecule is made up of alternating sugar and phosphate groups. More specifically, the sugar molecule in one nucleotide is connected to the phosphate group in the next nucleotide, creating a sugar-phosphate bond. This forms the "spine" of the DNA molecule, to which the nitrogenous bases are attached.

Step 3:
: Recall the structure of the sugar and phosphate components

The sugar component of the DNA backbone is called deoxyribose, which is a five-carbon sugar (pentose) with a hydrogen atom (instead of a hydroxyl group, -OH) attached to the second carbon atom. The phosphate group is composed of a central phosphorus atom bonded to four oxygen atoms, with one of the oxygen atoms bonded to the fifth carbon atom of the deoxyribose sugar in the nucleotide.

Step 4:
: Summarize the findings

The backbone of a DNA molecule is made up of alternating deoxyribose sugar and phosphate groups, forming a sugar-phosphate backbone. This backbone provides the structural framework for the DNA molecule, while the nitrogenous bases (adenine, guanine, cytosine, and thymine) attach to the sugar component of the nucleotides.

Final Answer

The components of the DNA backbone are alternating deoxyribose sugars and phosphate groups, which form a sugar-phosphate backbone.