#Question id: 16140

Many mouse genes are “tissue-specific,” that is, they are present throughout the body but are expressed in only one of the animal’s many tissue types. (Other mouse genes are expressed throughout the body, or in multiple tissues.) Geneticists can study the regulation of a mouse gene by fusing the gene’s promoter region to the LacZ coding sequence and injecting the construct to create a transgenic mouse. Fusion of the mouse amylase promoter to LacZ yielded a Pamylase-LacZ construct.

You are surprised to observe that mice homozygous for the transgene insertion display a serious heart defect. (Heterozygotes have normal hearts.) which one is a  possible explanation?

a) LacZ overexpression (with two copies of the transgene) causes the defect.

b) the insertion disrupted a gene that is haploinsufficient.

c) the insertion disrupted a gene that is haplosufficient.

d) LacZ expression inhibition (with two copies of the transgene) causes the defect.

Which of the following statements is correct  predict about the  heart defect?