Problem 65 - Chemistry: An Atoms-Focused Approach

Question

What are the three kinds of molecular subunits in DNA? Which two form the "backbone" of DNA strands?

Step-by-Step Solution

Answer

Answer: The two molecular subunits that form the backbone of DNA strands are phosphate groups and deoxyribose sugar molecules.

Step 1: Identifying the three molecular subunits in DNA

In DNA, there are three main types of molecular subunits: 1. Deoxyribonucleic acids (or nucleotides) 2. Phosphate groups 3. Sugars (in the case of DNA, it is deoxyribose)

Step 2: Understanding the structure of DNA

DNA is a double helix structure composed of two complementary strands. Each strand consists of a long chain of nucleotides. Every nucleotide is composed of: 1. A nitrogenous base (adenine, thymine, cytosine, or guanine) 2. A sugar molecule (deoxyribose) 3. A phosphate group These three parts are covalently bonded to each other, forming the building blocks of DNA.

Step 3: Identifying the backbone of DNA

The "backbone" of each DNA strand is a continuous chain formed by alternating deoxyribose sugar molecules and phosphate groups. These two components are covalently bonded together, creating a strong and stable structure for the DNA strand. So, the two molecular subunits that form the backbone of DNA strands are: 1. Phosphate groups 2. Deoxyribose sugar molecules