Answer:
Constitutive activation is the alteration of a protein or signaling pathway such that it is functional or engaged even in the absence of an upstream activating event. For example, RasD is constitutively active because it cannot bind GAP and therefore remains in the GTP-bound, active state even when cells are not stimulated by growth factor to activate a receptor tyrosine kinase.
Constitutively active Ras is cancer promoting because cells will proliferate in the absence of growth factors, and thus normal regulatory mechanisms for cell proliferation are bypassed.
(a) A mutation that resulted in Smad3 binding Smad4, entering the nucleus, and activating transcription independent of phosphorylation by the TGFβ receptor would render Smad3 constitutively active.
(b) A mutation that made MAPK active as a kinase and able to enter the nucleus without being phosphorylated by MEK would render MAPK constitutively active.
(c) A mutation that prevented NF-KB from binding to IK-B or that allowed NF-KB to enter the nucleus and regulate transcription even when bound to IK-B would render NF-KB constitutively active.
Answer:
Dispersal fundamentally influences spatial population dynamics but little is known about dispersal variation in landscapes where spatial heterogeneity is generated predominantly by disturbance and succession. We tested the hypothesis that habitat succession following fire inhibits dispersal, leading to declines over time in genetic diversity in the early successional gecko Nephrurus stellatus.
Explanation:
Answer:
<em>The fact that the left ventricle of the heart is thicker than the right ventricle reveals that it pumps blood against a greater resistance. -C.</em>
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<span>By definition, the two determinants of mean arterial pressure are cardiac output and total peripheral resistance. It has been shown that Lasix decreases cardiac output and total peripheral resistance. Diuretics increase urine production, so it will lower mean arterial pressure.</span>
