Following statements are regarding to apoptosis.

A. In the worm apoptotic pathway, CED-3 (caspase-9 in mammals) is a protease required to destroy cell components during apoptosis.

B. CED-4 (Apaf-1) was able to accelerate the autoproteolytic cleavage and activation of purified CED-9

C. Once EGL-1 causes dissociation of the CED-4/CED-9 complex, the released CED-4 dimer joins with three other CED-4 dimers to make an octamer, which then activates CED-3

D. Many apoptotic stimuli lead to damage of the outer mitochondrial membrane, causing release into the cytosol of several proteins that stimulate apoptosis. In particular, cytochrome c released from mitochondria activates Apaf-1, which in turn activates caspase-3 and 7.

Which of the following combination is incorrect?

#Question id: 1196

#Unit 4. Cell Communication and Cell Signaling

Cell signaling means all of the following except:

#Question id: 1197

#Unit 4. Cell Communication and Cell Signaling

In a signal transduction pathway, what is passed from the upstream member of the pathway to the downstream member?

#Question id: 1198

#Unit 4. Cell Communication and Cell Signaling

Both epinephrine and glucagon bind to G protein-coupled receptors and activate glycogen breakdown. Therefore, epinephrine and glucagon must:

#Question id: 1199

#Unit 4. Cell Communication and Cell Signaling

If you break liver cells by homogenization, separate the broken cell membranes (particulate) from the cytoplasm (soluble), and add epinephrine to the soluble portion, the result will be:

#Question id: 1200

#Unit 4. Cell Communication and Cell Signaling

Glucagon binds to the glucagon receptor, which interacts with a membrane-bound G protein, whose α subunit releases GDP and binds GTP. The α subunit then dissociates from the G protein and diffuses to a membrane-bound adenylyl cyclase which produces cAMP. In this scenario, name the

(1) transducer,

(2) effector,

(3) first messenger, and

(4) second messenger.

#Question id: 1201

#Unit 4. Cell Communication and Cell Signaling

Epinephrine binds to the same type of receptors in liver, fat, and smooth muscle cells. Yet in liver, glycogen breaks down; in fat, triacylglycerols break down; and smooth muscle cells relax. How can the same hormone produce three such different responses?