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[UltraSpiracle]

I don't know exactly where or how this will end up, but I think it would be a good idea to start it. Please submit as many items as you like. If and when it becomes too lengthy, and we gather enough items to start a word doc or pdf, I'll compile everything and post it. However, if this does take off, I don't expect it to do so until people start studying for the test again, whenever that might be.


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[UltraSpiracle]

I'll start.

1. Of the following, which is the MOST likely consequence of a constitutively active membrane tyrosine kinase receptor?

a absence of ligand binding
b decreased phosphorylation of MAP kinase
c decrease in intracellular [Ca]
d increased activity of Ras protein
e loss of signaling


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d - increased activity of Ras, since phosphorylation and activation of Ras is consequence of RTK signalling via the MAP kinase pathway.

Incorrect choices: a, since the constitutuvely active catalytic end of the receptor is intracellular, ligand binding would not likely be affected. b, MAP kinase is a downstream target and would likely exhibit increased phosphorylation, c since RTKs can influence levels of Ca via the PIP3 signaling cascade and e the "signal" would be amplified from the receptor.

2. In the conversion of 1 mole of fructose to pyruvate, inactivation of the enzyme triose phosphate isomerase would result in the net loss of

a 0 moles of ATP
b one mole of ATP
c two moles of ATP
c one mole of FADH2
e two moles of FADH2

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b, one mole of ATP, since DHAP cannot be converted to G3P, and thus you lose the equivalent of half the molecule of fructose for the pathway. Note that if this had been starting with glucose, the net loss would be two moles of ATP.