1A PCRQ Cell Communication & Development

Which of the options is not a general requirement for complex multicellular life?

Individual cells must retain a full range of functions, including reproduction.

The ability of cells to adhere to one another is fundamental to multicellularity.

True

For multicellularity to develop, there must be a mechanism of signaling among cells in the multicellular organism.

Which of the structures in the cell membrane receives signals from the environment or from other cells?

receptors

Many of the signaling pathways used for signaling between cells in complex multicellular organisms first evolved in:

 

unicellular eukaryotes.

A cell can only respond to signals from other cells, not from the physical environment.

False

The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on:

 

the presence of the appropriate receptors on the cells of the target tissue or organ.

Which is the correct order for these steps in cell signaling?

 

receptor activation, signal transduction, response

In many signaling pathways, once a signaling molecule binds to a receptor, the receptor becomes phosphorylated.

This initial phosphorylation step best demonstrates:

 

receptor activation.

Which signaling system involves the longest distance between release of a signaling molecule and activation of a receptor?

 

endocrine

Notch and Delta are both transmembrane proteins involved in cell communication in the developing nervous system of vertebrate animals. What makes Notch different from Delta?

 

Notch is a receptor, and Delta is a signaling molecule.

Growth factors such as platelet-derived growth factor (PDGF) function in:

 

paracrine signaling.

Kohler and Lipton first discovered platelet-derived growth factor (PDGF) by observing that fibroblasts:

Kohler and Lipton first discovered platelet-derived growth factor (PDGF) by observing that fibroblasts:

Most ligands form covalent bonds with their associated receptors, these complexes are more or less permanent and can only be broken through the hydrolysis of ATP.

false

A researcher is using a small molecule inhibitor that prevents phosphorylation as a tool to manipulate a signaling pathway. What is the most likely target of this small molecule inhibitor?

 

a receptor kinase

What does a ligand-gated channel do?

 

All of these choices are correct.

In the context of cell signaling, to what does the term ligand refer?

a signaling molecule that binds to the receptor

The first step following platelet-derived growth factor (PDGF) binding of the receptor is:

 

dimerization of the receptor.

What is the end-result of activating the MAP kinase pathway?

 

a change in gene expression

If two signaling pathways are activated simultaneously:

 

All of these choices are correct.

Why are some mutations of Ras associated with cancer?

 

Ras activates the MAP kinase signal transduction pathway that regulates cell division.