Cell Communication Diagram Quiz – Tap Each Signaling Step

All 15 parts on the diagram

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The three stages 8

Signaling molecule (ligand) It carries the message to the cell. A molecule that binds to a receptor is called a ligand.
Receptor protein It binds the signaling molecule. Binding changes its shape and starts the signal inside the cell.
Plasma membrane It is the boundary of the cell. Many signaling molecules cannot cross it, so they bind to receptors in it.
Reception The cell detects the signal. A signaling molecule binds to a receptor protein of the target cell.
Transduction The signal is passed on inside the cell. Each step can make the signal stronger.
Response The cell changes what it is doing. Here a gene in the nucleus is read.
Signaling cascade A chain of molecules, each activating the next. It is also called a signal transduction pathway.
Nucleus It holds the DNA. A signal can end here by switching the reading of a gene on or off.

A G protein pathway 7

G protein-coupled receptor A receptor that crosses the membrane seven times. With a signaling molecule bound, it activates a G protein.
G protein It links the receptor to an enzyme. It is switched on when GTP takes the place of GDP.
GTP GTP on the G protein means it is active. With GDP there, it is inactive.
Adenylyl cyclase An enzyme of the membrane that makes cyclic AMP from ATP. The active G protein switches it on.
Cyclic AMP (second messenger) A small molecule made from ATP. It spreads the signal inside the cell as a second messenger.
Protein kinase A An enzyme that cyclic AMP switches on. It adds phosphate groups to other proteins.
Phosphorylated protein A protein that has been given a phosphate group. That changes what the protein does in the cell.

How this list was compiled: Every name checked on 2026-10-01 against Nature Education, Scitable: Cell Signaling and GPCR; Kimball's Biology Pages: Cell Signaling, G Proteins and Second Messengers; Wikipedia: Cell signaling, Signal transduction, G protein-coupled receptor and Cyclic adenosine monophosphate, text only; and, for the names of the three stages, a 2013 exam review book read on archive.org. Licence: own work

The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work

How it works

This cell communication diagram quiz names a part of cell signaling and you tap it on the chart. Eight parts are on the chart of the three stages and seven on one G protein pathway. Misses are offered again after each chart.

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First chart: a stage or a thing

The five-sided tokens outside the cell are the signaling molecule, and the tall notched shape one of them sits in is the receptor protein. The three numbered tags along the bottom are the stages, in order: reception under the receptor, transduction under the chain of three shapes, response under the nucleus. That chain is the signaling cascade.

Second chart: keep the order

The pathway runs receptor, G protein, adenylyl cyclase, cyclic AMP, protein kinase A, phosphorylated protein. GTP is the small diamond on the G protein, not the oval itself. Cyclic AMP is the three small rings at the end of the arrow from ATP.

Reception is a stage and the receptor is a protein: each is asked in its own place.

Questions and answers

How is a signal amplified inside a cell?

Each step of a cascade makes the signal stronger. Once adenylyl cyclase is switched on, hundreds or even thousands of cyclic AMP molecules can be made, so a few signaling molecules at the surface can bring a large response inside.

How is a cell signal switched off?

The G protein turns its GTP back into GDP and is inactive again. An enzyme, phosphodiesterase, breaks down cyclic AMP, and protein phosphatases take the phosphate groups off proteins. None of these is drawn on the charts.

What are the three classes of membrane receptor?

G protein-coupled receptors, ion channel receptors and enzyme-linked receptors. The second chart follows a G protein-coupled receptor; the other two classes are not drawn.