Tutorial 6

Which of the following best describes long-distance signalling?

• It uses growth factors that are released into extracellular fluid.

• It involves ligands called hormones secreted by endocrine cells and transported through the bloodstream or sap.

• It involves direct cell-to-cell communication through gap junctions.

• It involves surface receptor interactions between cells.

What is the mechanism by which initiator caspases become activated?

• Initiator caspases are pre-formed dimers that are activated by cleavage of inter-subunit linkers.

• Initiator caspases are inactive monomers that are activated by prodomain-mediated dimerization and interchain cleavage.

• Initiator caspases become active upon direct interactions with executioner caspases.

• Initiator caspases are activated by phosphorylation at their catalytic site.

Which of the following molecules are involved in the activation of initiator caspases?

• Cytochrome C

• Apaf-1

• Bcl-2 and Bax

• FADD

Tumor necrosis factor receptor type 1-associated DEATH domain protein is a protein that in humans is encoded by the TRADD gene. TNFR1 belongs to the death receptor (DR) family of receptors.

Which of the following are true of the TRADD gene? (There may be more than one correct answer)

• It is part of a death-inducing signaling complex

• It activates the initiator caspases

• It is a transcription factor

• It activates the executioner caspases

What is one feature of a cell undergoing apoptosis? You may answer in 1-2 words.