• 15 parts
  • Checked October 2026

Cell Signaling Diagram Labeled

A signal arrives, is passed along and is answered: the three stages first, then one pathway step by step.

Cell Signaling Diagram Labeled

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
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Write the name of each numbered part.Answer key

  1. Signaling molecule (ligand)
  2. Receptor protein
  3. Plasma membrane
  4. Reception
  5. Transduction
  6. Response
  7. Signaling cascade
  8. Nucleus
  9. G protein-coupled receptor
  10. G protein
  11. GTP
  12. Adenylyl cyclase
  13. Cyclic AMP (second messenger)
  14. Protein kinase A
  15. Phosphorylated protein

Drawn for this site on 2026-10-01 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: what the membrane is made of

All 15 parts on the diagram

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The three stages 8

  1. Signaling molecule (ligand) It carries the message to the cell. A molecule that binds to a receptor is called a ligand.
  2. Receptor protein It binds the signaling molecule. Binding changes its shape and starts the signal inside the cell.
  3. Plasma membrane It is the boundary of the cell. Many signaling molecules cannot cross it, so they bind to receptors in it.
  4. Reception The cell detects the signal. A signaling molecule binds to a receptor protein of the target cell.
  5. Transduction The signal is passed on inside the cell. Each step can make the signal stronger.
  6. Response The cell changes what it is doing. Here a gene in the nucleus is read.
  7. Signaling cascade A chain of molecules, each activating the next. It is also called a signal transduction pathway.
  8. 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

  1. G protein-coupled receptor A receptor that crosses the membrane seven times. With a signaling molecule bound, it activates a G protein.
  2. G protein It links the receptor to an enzyme. It is switched on when GTP takes the place of GDP.
  3. GTP GTP on the G protein means it is active. With GDP there, it is inactive.
  4. Adenylyl cyclase An enzyme of the membrane that makes cyclic AMP from ATP. The active G protein switches it on.
  5. Cyclic AMP (second messenger) A small molecule made from ATP. It spreads the signal inside the cell as a second messenger.
  6. Protein kinase A An enzyme that cyclic AMP switches on. It adds phosphate groups to other proteins.
  7. 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

Cell signaling is how a cell takes in a message from outside and acts on it. The first chart shows the three stages: reception, transduction and response. The second follows one pathway from its receptor to protein kinase A.

Read the full guide

Read the first chart as a cell to cell communication diagram

A signaling molecule made by another cell binds to a receptor protein in the plasma membrane: reception. A cascade of molecules then passes the signal on inside the cell: transduction. The response here is in the nucleus, where a gene is read.

The second chart takes one receptor from a cell surface receptors diagram

A G protein-coupled receptor crosses the membrane seven times. Once a signaling molecule binds, GTP replaces GDP on the G protein. The G protein switches on adenylyl cyclase, which makes cyclic AMP from ATP. Cyclic AMP switches on protein kinase A.

  • Cyclic AMP: a second messenger. The first messenger is the signaling molecule outside the cell.

Questions and answers

What are the three stages of cell signaling?

Reception, transduction and response. A signaling molecule binds to a receptor, the signal is passed along a chain of molecules inside the cell, and the cell changes what it is doing, for example by reading a gene.

What does a diagram of cell signaling show?

A receptor in the membrane, the signaling molecule that fits it, the molecules that carry the signal inward, and the result. A diagram of cell communication may also draw the cell that sent the signal; this page starts at the cell that receives it.

What is a second messenger?

A small molecule made inside the cell after a receptor is activated. It spreads the signal to proteins in the cell. Cyclic AMP is a common one, made from ATP by the enzyme adenylyl cyclase.

What does a G protein do?

It links an activated receptor to an enzyme. With no signal it holds GDP. When the receptor is activated, GTP replaces the GDP, and part of the G protein goes on to activate a target such as adenylyl cyclase.

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