unit 3 cell signaling

Cell Signaling

The process by which cells communicate with each other through signaling molecules.

Signal Transduction Pathways

A series of molecular events and biochemical reactions triggered by a signal from outside the cell.

Reception

The first stage of cell signaling where the target cell detects a signaling molecule.

Transduction

The second stage of cell signaling which involves the conversion of a signal into a functional response within the cell.

Response

The final stage of cell signaling where the transduced signal triggers specific cellular activities.

Ligands

Molecules that bind specifically to receptors; can include proteins, peptides, amino acids, steroids, or gases.

Hydrophobic Signals

Signals such as steroid hormones that can pass through the plasma membrane to bind to intracellular receptors.

Hydrophilic Signals

Signals that cannot pass through the membrane and must bind to surface receptors.

G Protein-Coupled Receptors (GPCRs)

Membrane proteins that transmit signals inside the cell when activated by a ligand.

Receptor Tyrosine Kinases (RTKs)

Enzyme-linked receptors that autophosphorylate upon ligand binding to relay signals.

Ion Channel Receptors

Receptors that open or close in response to ligand binding, allowing ion flow to affect cell potential.

Intracellular Receptors

Receptors located in the cytoplasm or nucleus that influence gene expression by acting as transcription factors.

Phosphorylation Cascade

A sequence of events where proteins are phosphorylated, amplifying the initial signal.

Second Messengers

Small, non-protein molecules that amplify and spread signals within cells.

cAMP Pathway

A signaling pathway activated by GPCRs leading to the activation of protein kinase A (PKA).

Calcium Ions (Ca²⁺)

Important signaling molecules involved in various cellular processes, including muscle contraction.

Apoptosis

Programmed cell death, controlled by specific signaling pathways to maintain tissue health.

Innate Immunity

The rapid, non-specific immune response present at birth, including barrier defenses and internal defenses.

Adaptive Immunity

A specific immune response that develops over time and includes memory for faster reactions upon re-exposure.

Phagocytic Cells

Immune cells like neutrophils and macrophages that engulf and digest pathogens.

Natural Killer (NK) Cells

Immune cells that recognize and induce apoptosis in infected or cancerous cells.

Inflammatory Response

The immune response triggered by injury or infection resulting in increased blood flow and immune cell attraction.

Clonal Selection

The process where specific antigen binding triggers the expansion of B or T cells that recognize that antigen.

Effector Cells

Short-lived immune cells that actively combat pathogens.

Memory Cells

Long-lived immune cells that provide a faster response upon re-exposure to the same antigen.

Humoral Response

The part of adaptive immunity that involves B cells and the production of antibodies against pathogens.

Cell-Mediated Response

The part of adaptive immunity that involves T cells directly killing infected cells.

Cytokines

Signaling proteins secreted by immune cells that modulate the immune response.

Interleukins

A group of cytokines that promote the proliferation of immune cells.

Interferons

Proteins released in response to viral infections that help protect nearby cells from the virus.

Chemokines

Cytokines that direct the movement of immune cells towards infection sites.

MHC Proteins

Major Histocompatibility Complex proteins that present antigen fragments to T cells.

Autoimmune Diseases

Conditions where the immune system mistakenly attacks the body's own cells.

Immunodeficiency

A failure or lack of proper immune response, such as seen in AIDS.

Allergies

Overactive immune responses to harmless substances.