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gender of child would receive the defective gene (answer B).
46. B. DNA is hydrophilic and negatively charged. The lipids used to create the liposome-DNA
complex must be amphipathic (amphiphilic), with a cationic (positively charged) portion that
would complex with DNA.
47. A. It is important to make sure that therapeutic genes get to cells that can use them because
not all cells express the same genes. In general, all cells in an organism contain the same Page 5 of 12 genes (although there are some exceptions). The differences between cells of different types
are directly related to which genes are expressed and which are not expressed.
48. A. Somatic cells, as opposed to germ cells, do not take part in reproduction. The germ cells
are those that produce the sex cells such as spermatozoa and ova. Changes in somatic cells
are not passed on to offspring, so answer C is correct. Options C and D are incorrect because
they suggest that somatic cell DNA could be passed on. Answer B is incorrect, because there
is no reason to suspect that foreign DNA, if appropriately introduced into a germ cell
chromosome, would not be passed on to the offspring.
49. D. As dystrophin is found on the inner surface of the plasma membrane it is likely to be
involved in membrane integrity (answers A and B) and in ion transport (answer C). It is
unlikely to be involved in protein recognition (as those structures are normally located on the
outer surface of the cell).
50. B. The passage states that the gene dystrophin is 2.4 megabases in length. If mutation rates
are relatively constant across the entire genome, large genes such as dystrophin are more
likely to undergo a mutation than shorter genes. A is most likely incorrect since all DNA is
folded into chromosomes. C is also unlikely to be correct since the passage stated nothing
about other genes and there are no known genes that cause mutations in other genes. D is
incorrect because X-inactivation has to do with phenotype and genetic expression and not
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