Worksheet Questions: Cell Signaling

One cell sends second messengers to another cell through gap junctions. What type of signaling would this be considered?

• Endocrine

• Paracrine

• Synaptic

• Direct contact

In synaptic signaling, neurotransmitters are released into a space that is referred to as a:

• chemical synapse.

• neuron junction.

• gap junction.

• paracrine space.

In response to injury, cell fragments called platelets get activated to induce clotting. Activated platelets release factors that can in turn bind to specific membrane receptors on nearby cells. What type of signaling would this be considered?

• Paracrine

• Direct contact

• Endocrine

• Synaptic

Using a specific chemical, a cell biologist has blocked one type of channel-linked receptor in a lab rat's liver tissue. What was the likely mechanism of the chemical she used?

• The chemical prohibits second messenger signaling.

• The chemical prohibits binding of a ligand to the receptor.

• The chemical prohibits ions from entering the cell via active transport.

• The chemical causes ions to move in the opposite direction of the ion gradient.

Hormones such as glucocorticoids and mineralocorticoids are released from a cell and travel through the circulatory system to affect other cells throughout the body. Considering this information, what type of signaling do you think that glucocorticoids and mineralocorticoids stimulate?

• Endocrine

• Paracrine

• Synaptic

• Direct contact

Why are phosphorylation and dephosphorylation reactions commonly used to regulate signal transduction pathways?

• The addition or removal of a phosphate group can expose or hide potential binding sites in proteins or change protein activity

• Protein kinases and phosphatases are abundant in most cells

• Phosphate groups are efficient second messengers

• The hydrolysis of bound GTP generates GDP, which can change the activity of proteins bound to GDP

These molecules can directly convert extracellular signals into intracellular signals.

• Receptors

• Second messengers

• Hormones

• Transcription factors

1 / 1 pts When bound to ligand, this type of receptor changes conformation to allow ions to move down their concentration gradient across the membrane:

• Channel-linked receptor

• Steroid hormone receptor

• Enzymatic receptor

• G protein-coupled receptor

1 / 1 pts What type of receptor is not an enzyme, but is directly associated with an enzyme that can hydrolyze GTP?

• Enzymatic receptor

• Channel-linked receptor

• Steroid hormone receptor

• G protein-coupled receptor

1 / 1 pts What property defines most ligands for intracellular receptors?

• They are hydrophilic

• They are molecules that can perform significant hydrogen bonding interactions with water

• They are lipid-soluble

• They are large molecules