In squirrels and chipmunks, as in humans, cholesterol is removed from the circulation, first by complexing with Low Density Lipoproteins (LDLs). Next, the cholesterol-LDL complex is bound to LDL receptors found predominantly on the surface of liver cells, which then undergo receptor-mediated endocytosis, thus removing the LDL-cholesterol from the blood serum. Inside the cells, a drop in pH causes the LDLs to separate from their receptors, and the receptors are ultimately returned to the cell surface via exocytosis. You are surprised to discover that in both squirrels and chipmunks, certain individuals are predisposed to suffering heart attacks at an early age, and these early heart attacks are linked to the presence of a mutation in the gene that codes for their LDL receptors. This is where the similarity ends. Word has spread about your groundbreaking work with the hypercholesterolemic squirrels and chipmunks, and you receive a call one night from an RA in Eigenmann. Evidently, two students had been secretly keeping their pet mice in their dorm rooms. The mice had somehow escaped and shortly thereafter, black mice have begun popping up all over the place. The two students claim it couldn’t have been their mice that produced the numerous black mice, because they each owned a white mouse that the pet store owner assured them was purebred for coat color. Determined to get to the bottom of this, you capture a few pairs of the F1 black mice and cross them together. The cross yields 27 black mice and 21 white mice in the F2 generation. Certain that you have solved the mystery, you write a report to email to the Eigenmann RA. NAME and DEFINE the genetic phenomenon illustrated here, and EXPLAIN the evidence that suggests that this is the correct explanation for these observations.
In squirrels and chipmunks, as in humans, cholesterol is removed from the circulation, first by complexing with Low Density Lipoproteins (LDLs). Next, the cholesterol-LDL complex is bound to LDL receptors found predominantly on the surface of liver cells, which then undergo receptor-mediated endocytosis, thus removing the LDL-cholesterol from the blood serum. Inside the cells, a drop in pH causes the LDLs to separate from their receptors, and the receptors are ultimately returned to the cell surface via exocytosis.
You are surprised to discover that in both squirrels and chipmunks, certain individuals are predisposed to suffering heart attacks at an early age, and these early heart attacks are linked to the presence of a mutation in the gene that codes for their LDL receptors. This is where the similarity ends.
Word has spread about your groundbreaking work with the hypercholesterolemic squirrels and chipmunks, and you receive a call one night from an RA in Eigenmann. Evidently, two students had been secretly keeping their pet mice in their dorm rooms. The mice had somehow escaped and shortly thereafter, black mice have begun popping up all over the place. The two students claim it couldn’t have been their mice that produced the numerous black mice, because they each owned a white mouse that the pet store owner assured them was purebred for coat color. Determined to get to the bottom of this, you capture a few pairs of the F1 black mice and cross them together. The cross yields 27 black mice and 21 white mice in the F2 generation. Certain that you have solved the mystery, you write a report to email to the Eigenmann RA. NAME and DEFINE the genetic phenomenon illustrated here, and EXPLAIN the evidence that suggests that this is the correct explanation for these observations.
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