Question

activator ~3 min

1. what is the shape of dna?
2. what is the monomer (or

building block) of dna?

1. what are the names of nitrogen

bases and how are they grouped?

Explanation:

1. DNA has a double - helix shape. This was discovered by Watson and Crick. The two strands of DNA wind around each other like a twisted ladder.
2. The monomer (building block) of DNA is the nucleotide. A nucleotide consists of a deoxyribose sugar, a phosphate group, and a nitrogen - containing base.
3. The nitrogen bases in DNA are adenine (A), thymine (T), guanine (G), and cytosine (C). Adenine pairs with thymine (A - T) and guanine pairs with cytosine (G - C). These pairings are due to hydrogen bonding. Adenine and guanine are purines (double - ring structures), while thymine and cytosine are pyrimidines (single - ring structures).

Answer:

1. Double - helix.
2. Nucleotide.
3. Nitrogen bases: adenine (A), thymine (T), guanine (G), cytosine (C). Grouping: A pairs with T, G pairs with C. Purines (A, G) and pyrimidines (T, C).