Cell Communication

cell communication

The process by which cells send and receive signals to coordinate their activities, regulate gene expression, and respond to external stimuli.

conformation

By changing the _______ of a receptor, signals lead to a response inside the cell

Apoptosis

Signals intentionally causing a cell to die

To respond to a changing environment. Critical for survival. To communicate with each other.

Why do cells need signals?

Auxin

Signaling molecule responsible for phototropism

Direct Intercellular Signaling

Cell junctions allow signaling molecules to pass from one cell to another

Contact-dependent signaling

Molecules bound to the surface of cells serve as signals to cells coming in contact with them

Autocrine signaling

Cell secrete signaling molecules that bind to their own cell surface or similar neighboring cells

Paracrine signaling

Signal does not affect originating cell, but doesn’t influence nearby cells

Endocrine signaling

Signals called hormones travel long distances and are usually longer lasting in effect

receptor activation

A receptor on a cell's surface or inside the cell is triggered by a signaling molecule.

Signal transduction

A signal transduction pathway. Activated receptor stimulates a sequence of changes.

Cellular response

• Change enzyme activity

• Change function of structural proteins

• Change gene expression

Ligand

A molecule that binds noncovalently to a specific site on a protein, such as a receptor, to initiate a biological response. The binding of a _______ can activate or inhibit the protein's function.

Conformational Change

Ligand binding changes receptor structure this ___________ transmits the signal across the membrane

Inactive again

Once a ligand is released, the receptor reverts and is _______

What are the three main types of cellular receptors?

The three main types of cellular receptors are ion channel receptors, G protein-coupled receptors, and enzyme-linked receptors.

Enzyme-linked receptors

Found in all living species. The extracellular domain binds signal while the intracellular domain becomes functional catalyst. Most are protein kinases

protein kinases

Enzymes catalyze the transfer of phosphate groups from ATP to specific target proteins, regulating their activity.

G-Protein coupled receptors (GPCR)

All Eukaryotes. 7 transmembrane segments.

Explain G-protein coupled receptors.

• The activated receptor binds to G protein

• Releases GDP and binds GDP instead of GTP causes G protein to dissociate

• α subunit and β/γ dimer interact with other proteins in a signaling pathway

ion channels

Ligand binding causes ____ to open and allow ions to flow through the membrane

Synaptic signals

In animals, ion channels transmit ________ between neurons and muscles or between two neurons.

Intercellular receptors

Receptors inside the cell

What produces the cellular response to signals?

A signaling molecule binds to the cell surface receptor and the conformation change stimulates a signal transduction pathway

signal transduction pathway

The process by which a cell converts an extracellular signal into a specific cellular response.

What type of cell surface receptor is a receptor tyrosine kinase?

intrinsic kinase activity.

First messenger

Signals binding to a cell surface are ____

Second messengers

Many signal transduction pathways lead to production of ______. Relaying signals inside the cell

Signal amplification (cAMP one of two advantages)

Binding of signal to one receptor can cause the synthesis of cAMP molecules that activate PKA and each PKA can phosphorylate many proteins

Speed (cAMP one of two advantages)

In one experiment a substantial amount of cAMP was made within 20 seconds after addition of signal

Hormonal Signaling

The response to a given signaling molecule depends of which cell is responding

proteome relating to hormonal signaling

refers to all proteins in a cell, crucial for hormonal signaling pathways regulating. Determining the variation in response.