Question

True or False

_____ In the JAK/STAT pathway, the JAK proteins first phosphorylate STAT1 and STAT2 and then phosphorylate the cytokine receptors.

_____ The function of the protein dynamin is required during assembly of the clathrin coat.

______ Stimulation of transcription followed by translation would be considered a fast intracellular response to an extracellular signal.

______ Phosphorylation of plasma membrane phospholipids can create binding sites for intracellular signaling proteins.

Answer 1

True or False

FALSE In the JAK/STAT pathway, the JAK proteins first phosphorylate STAT1 and STAT2 and then phosphorylate the cytokine receptors.

In the JAK/STAT pathway, the JAK proteins are first phosphorylated / activated and they then phosphorylate STAT proteins. Cytokine receptors are involved in the activation of the JAK/STAT pathway but not in the order given here (i.e. the JAK proteins first phosphorylate STAT1 and STAT2 and then phosphorylate the cytokine receptors).

FALSE The function of the protein dynamin is required during assembly of the clathrin coat.

Dynamin is a GTPase that is required for endocytosis. Although it plays a vital role in clathrin-dependent endocytosis, it is not required during the assembly of the clathrin coat. Dynamin plays a role in vesicle formation after the assembly of clathrin. Specifically Dynamin helps in the constriction around the vesicle necks and thus in the formation of constricted coated pits.

TRUE Stimulation of transcription followed by translation would be considered a fast intracellular response to an extracellular signal.

An extracellular signal can be in the form of signalling molecules like growth factors, hormones, neurotransmitors and so on. These extracellular signals are meant to cause some pgysiological process or pathway or even a simple intracellular response which is mediated through protein synthesis and thus stimulation of transcription followed by translation would be considered a fast intracellular response to an extracellular signal.

FALSE Phosphorylation of plasma membrane phospholipids can create binding sites for intracellular signaling proteins.

Although plasma membrane phospholipids do play a role in regulating certain cellular processes and in certain pathways, it is the phosphorylation og signalling proteins that are more directly involved in intracellular signaling.