Question

part b

1. the diagram below shows two nitrogen bases. determine which is a purine and which is a pyrimidine. label and explain why you made your choice. (4pts)

a. pyrimidines
b. purine

1. which of the two molecules below represents a molecule of deoxyribose? (1pt)

1. name the structure below and label the 3 parts. (4pts)

name of structure: nucleic acid
a.

1. how are sulfhydryl functional groups important to proteins? (2pts)

ap biology test three-biomolecules and origins of life
page 8 of 10

Explanation:

For question 1: Purines have a double - ring structure and pyrimidines have a single - ring structure. In the given diagrams, structure A has a single - ring (pyrimidine) and structure B has a double - ring (purine).
For question 2: Deoxyribose has one less oxygen atom than ribose. In the given structures, structure A has an - OH group at the 2' position (ribose), while structure B has an - H at the 2' position (deoxyribose).
For question 3: The structure is a nucleotide. A nucleotide is composed of three parts: a phosphate group (A), a pentose sugar (C), and a nitrogenous base (B).
For question 4: Sulfhydryl (-SH) functional groups are important to proteins because they can form disulfide (-S - S -) bonds. These disulfide bonds contribute to the tertiary and quaternary structures of proteins by covalently linking different parts of the polypeptide chain or different polypeptide chains.

Answer:

1. A is a pyrimidine (single - ring structure) and B is a purine (double - ring structure).
2. B represents deoxyribose.
3. The structure is a nucleotide. A is phosphate group, B is nitrogenous base, C is pentose sugar.
4. Sulfhydryl functional groups form disulfide bonds which stabilize protein structure.