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Indietro

Chapter 11 Cell Signaling

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Termini in questo insieme (24)

  • Paracrine Signaling-

    A signaling cell that secretes molecules which diffuse locally over short distances to bind to receptors on neighboring target cells

  • Synaptic Signaling

    A nerve cell releases nuerotransmitter molecules through a synapse to act on target cell

  • Endocrine Signaling

    • Hormones are released directly into the bloodstream.

    • Travel to and act on distant target cells

  • Hormones

    • Chemical messengers

    • Travel through the bloodstream

    • Target distant cells with matching receptors

  • Ligand

    • Signaling molecule

    • Binds specifically to a receptor

    • Initiates a cellular response

  • Cell Signaling Stage 1: Signal Reception

    • Ligand binds to a receptor protein

    • Causes receptor to change shape

    • Occurs on or inside the target cell

  • Cell Signaling Stage 2: Signal Transduction

    • Relays signal from receptor to target

    • Involves a series of molecular steps

    • Dependent on molecular interactions

  • Cell Signaling Stage 3: Cellular Response

    • Final outcome of the pathway

    • Triggers nuclear gene expression OR

    • Alters cytoplasmic enzyme activity

  • G-Protein

    • Molecular switch inside the cell

    • Transmits external signals across membrane

    • Alternates between active and inactive states

  • G-Protein Coupled Receptor (GPCR)

    • Cell-surface transmembrane receptor

    • Works cooperatively with a G-protein

    • Triggers downstream cascades

  • Tyrosine Kinases (RTKs)

    • Cell-surface receptor protein class

    • Binds hormones, growth factors, or cytokines

    • Triggers multiple pathways simultaneously

  • Ligand-Gated Ion Channel

    • Fast-acting transmembrane protein

    • Opens/closes when a ligand binds

    • Allows specific ions to pass through

  • : Intracellular Receptors

    • Located in cytoplasm or nucleus

    • Binds small, hydrophobic signals

    • Molecules must freely cross plasma membrane

  • Protein Kinase

    • Enzyme that regulates protein activity

    • Transfers phosphate from ATP to protein

    • Executes the process of phosphorylation

  • Phosphorylation Cascade

    • Series of chemical reactions in signaling

    • Kinases sequentially phosphorylate each other

    • Amplifies the incoming signal significantly

  • Protein Phosphatases

    • Enzymes that remove phosphate groups

    • Executes dephosphorylation

    • Reverses the effects of protein kinases

  • Second Messengers

    • Small, non-protein molecules

    • Intracellular relay signals

    • Spreads rapidly throughout cytoplasm

  • Cyclic AMP (cAMP)

    • Critical intracellular second messenger

    • Relays hormone and neurotransmitter signals

    • Drives downstream cellular responses

  • Adenylyl Cyclase

    • Membrane-bound enzyme

    • Converts ATP into Cyclic AMP (cAMP)

    • Activated by an extracellular signa

  • Inositol Trisphosphate (IP3)

    • Intracellular second messenger

    • Created by cleavage of (PIP2)

    • Triggers(Ca2+) release from the ER

    • Raises cytoplasmic calcium concentration

  • Diacylglycerol (DAG)

    • Lipid second messenger

    • Stays in the plasma membrane

    • Produced by (PIP2) cleavage

    • Activates downstream protein kinases

  • Scaffolding Proteins

    • Large relay proteins

    • Binds multiple pathway enzymes simultaneously

    • Increases signaling efficiency and speed

  • Apoptosis

    • Programmed cell death

    • Cellular suicide mechanism

    • Uses orderly enzyme cascades

    • Prevents damage to neighboring cells

  • Apoptosis: Cellular Blebbing

    • Structural change during apoptosis

    • Cell membrane bulges outward

    • Forms contained pockets (blebs)

    • Prepares cell for clean disposal