cell signaling

Signaling Cell

The source of a signaling molecule.

Signaling Molecule

The carrier of information transmitted when the signaling molecule binds to a receptor, also called a ligand. Signaling molecules vary greatly and include peptides, lipids, and gases.

Receptor Protein

The molecule on the responding cell that binds to the signaling molecule.

Responding Cell

The cell that receives information from the signaling molecule.

Example of cell signaling

(Fight or Flight response)

You’re startled or scared. You get a feeling in your stomach and your hearts beating faster. For these changes to happen the signaling molecule is the hormone adrenaline a.k.a. (Epinephrine.) Adrenaline is released from the adrenal glands, located above the kidneys. It circulates through the body and acts on many types of cells, including the cells in your heart, causing it to beat more strongly and quickly. As a result, the heart is able to deliver oxygen more effectively to the body.

Receptor Activation

The “turning on” of a receptor, which often occurs when a signaling cell molecule binds to a receptor on a responding cell.

Signal Transduction

The process in which an extracellular molecule acts as a signal to activate a receptor, which transmits information to the cell through the cytoplasm. (Like a chain reaction of one molecule activating the next and so on.)

Cellular Response

A change in cellular behavior, such as activation of enzymes or genes, following a signal.

Termination

1. In DNA replication it’s the process by which DNA polymerase stops replicating and is released

2. In transcription it’s the process by which RNA polymerase stops transcribing and the transcript is released. Which occurs when RNA polymerase encounters a sequence in the DNA template strand called a terminator.

3. In translation it’s the process by which the addition of amino acids stops and the completed polypeptide is released from the ribosome, which occurs when the ribosome encounters a stop codon.

4. In cell communication it’s the stopping of the response of a cell triggered by a signal.

4 elements of cell signaling

Signaling cell, signaling molecule, a receptor protein, a responding cell.

What steps occur when a signaling molecule binds to a receptor on a responding cell?

Receptor activation, signal transduction, response, and termination.

If a hormone is released into the bloodstream and comes in contact with many cells, what determines which cells in the body respond to the hormone?

Only cells that have receptors for the hormone respond to the signal.

Endocrine Signaling

Signaling by molecules that travel through the bloodstream.

Paracrine Signaling

Signaling by a molecule that travels a short distance to the nearest neighboring cell.

Growth Factor

Soluble molecules, usually paracrine signals that affect cell growth division and changes in gene expression

Autocrine signaling

Signaling between different parts of the same cell.