(3) Cell Communication

Intercellular Signaling

Communication between cells.

Intracellular Signaling

Communication within a cell.

Ligands

Molecules released by signaling cells that bind to target molecules to deliver a chemical signal.

Phosphorylation Cascade

A sequence of signaling pathway events where one enzyme phosphorylates another, causing a chain reaction.

Second Messenger

Molecules that relay signals received at receptors on the cell surface to target molecules in the cytosol or nucleus to amplify the signal.

Nuclear Response

Changes in gene expression, which involves using information from a gene to produce a functional product, typically a protein.

Cytoplasmic Response

Changes in a cell's metabolic response, where metabolic enzymes become more or less active.

Change in Membrane Potential

When ligands open ion channels in neurons, leading to a change in electrical charge across the membrane.

Paracrine Signaling

Signaling that targets nearby cells through diffusion in the extracellular matrix.

Endocrine Signaling

Signaling where a cell targets a distant cell through the bloodstream.

Autocrine Signaling

Signaling where a cell targets itself

Signaling Across Gap Junctions

Signaling between cells through plasma membranes using small signaling molecules that diffuse between cells.

Internal (Cytoplasmic) Receptors

Receptors found in the cytoplasm that respond to hydrophobic ligand molecules to promote gene expression.

Cell-Surface Receptors

Membrane-anchored proteins that bind to external ligand molecules and perform signal transduction.

Ion Channel-Linked Receptors

Under Cell-Surface Receptors:

Receptors that bind a ligand and open a channel through the membrane for specific ions.

Enzyme-Linked Receptors

Under Cell-Surface Receptors:

Receptors that bind an extracellular ligand and activate enzymatic activity on their intracellular side.

G Protein-Linked Receptors

Under Cell-Surface Receptors:

Receptors that translate extracellular signals into intracellular biological responses.

Small Hydrophobic Ligands

Ligands that diffuse through the plasma membrane and interact with internal receptors.

Water-Soluble Ligands

Ligands that are too large or polar to pass through the plasma membrane and bind to cell-surface receptors.

Steroid Hormones

Small hydrophobic ligands including estradiol, testosterone, and cholesterol.

Peptide Hormones

Polar, water-soluble ligands that cannot cross the plasma membrane unaided and bind to cell-surface receptors.

1st step of cell signaling

reception of the signal from extra or intracellular response

2nd step of cell signaling

transduction of the signal

• phosphorylation cascade

• second messengers

3rd step of cell signaling

cellular response

• Nuclear

• Cytoplasmic

• Changes in membrane potential

What enzyme is used for phosphorlyation?

protein kinase

second messenger molecules

• cyclic nucleotides

• inositol trisphosphate and diacylglycerol

• calcium ions (Ca²⁺)

what is the response of paracrine signaling?

quick and last for a short period of time

what is the response of endocrine signaling?

slow but long lasting effect

What type of glands and cells do endocrine signaling come from?

endocrine glands and cells

response of autocrine signaling?

• regulates pain sensation and inflammatory responses.

• signal itself to undergo programmed cell death

• Cellular differentiation during embryo development

what happens to receptors when bounded to a ligand?

change in receptor shape

what happens when a cell surface receptor malfunctions?

sever consequences, such as mutations, overamplification, etc.

3 domains that make up cell surface-receptors

extracellular domain, transmembrane domain, and intracellular domain

3 types of cell-surface receptors

• Ion Channel-Linked Receptors

• Enzyme Linked-Receptors

• G Protein-Linked Receptors

Which hormones regulate gene expression?

estradiol and testosterone