Cultures of two different human cell types are exposed to the same steroid signaling molecule. Analysis of gene expression shows that only one of the cell types activated gene expression characteristic of the steroid signaling pathway. Which of the following is the most likely explanation for this difference? The steroid ligand can only cross the plasma membrane in one cell type. Only one of the cell types expresses the cognate steroid receptor. Only one cell type contains the DNA sequences that the steroid receptor binds to. Only one cell type phosphorylates the steroid ligand to activate it. Question 16 (6 points) A plot of v0 versus [S] for aspartyl transcarbamoylase displays three sigmoidal lines. If the line in the middle represents the enzyme activity in the absence of any allosteric effectors, then the line to the represents the enzyme in the when bound to right; R state; CTP right; T state; CTP left; T state; GTP left; R state; GTP