For optimal activity, of lysosomal acid hydrolases they need to be___

a)Activation based on sensitivity to cleavage by endoglycosidase-D

b)Activation by proteolytic cleavage

c)Requires an acid environment

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#Question id: 14739

#Unit 4. Cell Communication and Cell Signaling

In heart muscle, activation series of the muscarinic acetylcholine receptor its effector K+ channel via the Gβγ subunit of a Gi protein.

a. Binding of acetylcholine triggers activation of the Gαi subunit and its dissociation from the Gβγ subunit in the usual way. 

b. The released Gβγ subunit (rather than Gαi∙GTP) binds to and opens the associated effector protein, a K+ channel. 

b. The increase in K+ permeability hyperpolarizes the membrane, which reduces the frequency of heart muscle contraction. 

d. Activation is terminated when the GTP bound to Gαi is hydrolyzed (by a GAP enzyme that is an intrinsic part of the Gαi subunit) to GDP and Gαi∙GDP recombines with Gβγ.

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#Question id: 4354

#Unit 3. Fundamental Processes

Which of the following statements correctly describes the primary difference between enhancers and proximal control elements?

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#Question id: 31382

#Unit 4. Cell Communication and Cell Signaling

The activation of PI 3-kinase leads to the activation of a kinase, known as:

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#Question id: 23658

#Unit 13. Methods in Biology

How many recombinant clones must be screened in order to be 99% certain that a particular gene is found in a YAC library of human DNA where the average size of an insert is 500 kbp? The human genome size is about 3.2 x 10⁶ kbp. 

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#Question id: 5605

#Unit 5. Developmental Biology

Double fertilization is a unique feature of flowering plants. In this process, one sperm unites with the egg to yield a zygote. The second sperm unites with the polar nuclei to initiate the formation of the