Chapter 02: Genes and Genetic Diseases MULTIPLE CHOICE 1. A nurse recalls the basic components of DNA are: a. pentose sugars and four phosphate bases. b. a phosphate molecule, deoxyribose, and four nitrogenous bases. c. adenine, guanine, and purine. d. codons, oxygen, and cytosine. ANS: B The three basic components of DNA are deoxyribose; a phosphate molecule; and four types of nitrogenous, not phosphate, bases. DNA does not contain condone. REF: p. 38 2. Which of the following mutations have the most significant effect on protein synthesis? a. Base pair substitutions b. Silent mutations c. Intron mutations d. Frameshift mutations ANS: D The frameshift mutation involves the insertion or deletion of one or more base pairs of the DNA molecule. This greatly alters the amino acid sequence, which affects protein synthesis. The base pair substitution is a type of mutation in which one base pair replaces another. Silent mutations do not change amino acids or protein synthesis. Intron mutations are part of RNA sequencing. REF: p. 39