AP BIOLOGY: Cell-Cell Communication Study Sheet

Local Cell-Cell Communication

Includes junctions, paracrine signaling (growth factors), and synaptic signaling.

Long-Distance Cell-Cell Communication

Primarily involves endocrine signaling through hormones.

Three Steps of Cell Signaling

Reception, Transduction, Response.

Reception of Hydrophobic Ligands

Hydrophobic or small ligands pass through the membrane and bind to internal receptors.

Reception of Hydrophilic Ligands

Hydrophilic or large ligands bind to receptors on the cell membrane.

G-Protein Linked Receptors

Ligand binding activates G-protein via GDP to GTP exchange, activating enzyme and starting signaling transduction pathways.

Receptor Tyrosine Kinase Mechanism

Two ligands bind to receptors forming a dimer, activating kinase activity to relay signals.

Ligand-Gated Ion Channels

Ligand binding opens receptor gates allowing ions to flow in, generating electrical signals.

Relay Molecules

Proteins that propagate signals through phosphorylation changes, activating other relay proteins.

Protein Kinases

Relay molecules that transfer phosphate groups from ATP to other proteins to continue signaling.

Protein Phosphatases

Enzymes that remove phosphate groups, allowing reuse of protein kinases.

Secondary Messengers

Small ions or molecules that relay signals within the cell, used in G-protein and RTK pathways.

cAMP Function

cAMP activates protein kinase A after being produced from ATP, leading to phosphorylation of target proteins.

Phosphodiesterase Role

Converts cAMP to AMP, turning off the signaling cascade.

Cholera Toxin Effect

Causes G-proteins to remain active, leading to excessive cAMP production and loss of salt and water in intestines.

Calcium Ions (Ca+) in Signaling

Ca+ channels are opened by IP3 signaling, releasing stored Ca+ to activate other proteins.

Cytoplasmic Response

Cellular pathways that activate enzymes to initiate cellular responses.

Nuclear Response

Transcription factors are activated to turn on genes coding for enzymes.

Signal Amplification

The principle that more signaling steps lead to a stronger response.

Response Specificity

More signaling steps provide a more tailored cellular response.

Sensory Receptors

Cells that detect stimuli like sugar or salt and trigger signal transduction pathways.

Sensory Adaptation

Diminished sensitivity to a stimulus over time, leading to fewer signals to the brain.

Proto-Oncogenes

Genes that code for proteins promoting cell division; mutated forms can lead to cancer.

Tumor-Suppressor Genes

Genes like p53 that prevent uncontrolled cell division; mutations can lead to cancer.

Apoptosis

Programmed cell death process involving caspases and proteases.

Ced-9 and Apoptosis

Ced-9 inhibits Ced-4 and activation of Ced-3, which initiates the apoptotic process.