Normally, the FgfR3 protein (a receptor tyrosine kinase) is activated by a fibroblast growth factor and signals the chondrocytes to stop dividing and begin differentiating into cartilage. This signal is mediated by the Stat protein, which is phosphorylated by activated FgfR3 and then translocated into the nucleus. Inside the nucleus, Stat activates the genes encoding a cell cycle inhibitor, the p21 protein. The mutation in FgfR3 causes the lethal condition thanatophoric dysplasia. This condition may be achieved by:

A. Mutations in the extracellular domain of the FgfR3 protein

B. Mutations in the tyrosine kinase intracellular domain of the FgfR3 protein

C. Mutations in the transmembrane domain of the FgfR3 protein

Which of the following is correct?

#Question id: 11154

#Unit 9. Diversity of Life Forms

Concerning growth in genome size over evolutionary time, which of these does not belong with the others?

#Question id: 11155

#Unit 9. Diversity of Life Forms

Nucleic acid sequences that undergo few changes over the course of evolutionary time are said to be conserved. Conserved sequences of nucleic acids

#Question id: 11156

#Unit 9. Diversity of Life Forms

Species that are not closely related and that do not share many anatomical similarities can still be placed together on the same phylogenetic tree by comparing their

#Question id: 11157

#Unit 9. Diversity of Life Forms

Typically, mutations that modify the active site of an enzyme are more likely to be harmful than mutations that affect other parts of the enzyme. A hypothetical enzyme consists of four domains (A—D), and the amino acid sequences of these four domains have been determined in five related species. Given the proportion of amino acid homologies among the five species at each of the four domains, which domain probably contains the active site?

#Question id: 11158

#Unit 9. Diversity of Life Forms

Which of these items does not necessarily exist in a simple linear relationship with the number of gene-duplication events when placed as the label on the vertical axis of the graph below?

#Question id: 11159

#Unit 9. Diversity of Life Forms

Which kind of DNA should provide the best molecular clock for gauging the evolutionary relatedness of several species whose common ancestor became extinct billions of years ago?