Question

1. The two structures for cell-cell attachment in animals are:

		plasmodesmata, desmosomes
		plasmodesmata, gap junctions
		tight junctions, desmosomes
		gap junctions, desmosomes

2. The correct order of the 4 consecutive steps of ALL intercellular signaling pathways is

		Step 1) reception, Step 2) response, Step 3) transduction, Step 4) deactivation
		Step 1) reception, Step 2) processing, Step 3) response, Step 4) deactivation
		Step 1) reception, Step 2) processing, Step 3) response, Step 4) deactivation
		Step 1) reception, Step 2) response, Step 3) transduction, Step 4) deactivation

Answer 1

Answer 1) Gap junctions and desmosomes.

Gap junctions are composed of connexin proteins and these are channels between cells from where ion molecules and water passes.

Desmosomes are the junctions found in animal cells that links two cells together with a complex of adhesion proteins. Cadherins are one among them.

Answer 2) 1 RECEPTION, PROCESSING, RESPONSE, DEACTIVATION

Reception step involves that a cell perceives a signal outside of the cell and this signal binds to the receptor present on membranes of the cell or intracellular receptors of the cell.

Processing involves many steps in which chemical nature of various molecules changed and also with the help of secondary messengers the signal is processed properly.

Response includes the cellular response for which the signal has been generated.

Deactivation includes the conformational change which occurred due to signal now to the normal cellular conditions such as phosphorylation and dephosphorylation.