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AP Bio. Cell Communication
The growth and survival of the cell is dependent on cell communication
Cells can communicate through 3 general ways
Direct- (substances pass freely through cytoplasm to adjacent cells) Ex. Immune cells
- Animals- Gap Junctions, Plants-Plasmodesmata
Local – messages secreted over a short distance from cell-to-cell via extracellular fluid.
- Synaptic-nervous systems (neurotransmitters)
- Paracrine- almost all others, release local regulators(ex. Growth hormones) via exocytosis
Long distance- hormone signaling. Ex. Insulin
- Plants- hormones through xylem and phloem (vascular tissue) or air.
- Animals- hormones through endocrine signaling. Into circulatory system.
Three stages of Cell signaling
-Reception- ligand(any macromolecule that binds to a signal molecule) is detected and then binds to receptor. This is highly specific. Lock and Key. Then it initiates Transduction. Can be plasma membrane or intracellular
- Plasma Membrane- most common, polar, hydrophilic, and large. (Ex. G-proteins, ligand gated ion channels)
- Intracellular- found in nucleus or cytoplasm. Binds to ligand that can pass through membrane (hydrophobic, small, nonpolar). (Ex. Nitric oxide/gasses, or steroids and thyroid hormones)
Stage 2: Transduction- The conversion of an extracellular signal to an intracellular signal that will bring about a cellular response
- Kinase: Adds a phosphate from ATP. Relays the signal inside
- Phosphatase: Takes a phosphate to shut off the pathway.
Second messengers are used during transduction to relay and amplify the response. They are small, non-protein molecules and ions. (Ex. Cyclic AMP or cAMP)
Stage 3: Response- The final molecule changes the signal to a response which then alters a cellular process.
- Examples: Alter membrane permeability, change metabolic process, and protein that turns genes on or off
Signal transduction pathways can influence how a cell responds to its environment. This can result in charges in gene expression and cell function. (this can alter phenotype or result in cell death)
Any sort of change (mutations) to receptor proteins or to any component of the signaling pathway will result in a change to the transduction of the signal.
In eukaryotic organisms two main cell membrane receptors are G proteins coupled receptors and ion channels
- GPCRs: Largest category of cell surface receptors, important in animal sensory systems, and binds to a G protein that can bind to GTP, which is an energy molecule similar to ATP. The GPCR enzyme and G protein are inactive until ligand binding to GPCR on the extracellular side. Ligand binding causes cytoplasmic side to change shape, allows for the G protein to bind to GPCR. Activates the GPCR and G proteins. GDP becomes GTP. Part of the activated G protein can then bind to the enzyme. Activates enzyme, amplifies signal and leads to a cellular response.
- Ion Channels: Ligand gated ion channels, located in the plasma membrane, important in the nervous system, receptors that act as a gate for ions. When a ligand binds to the receptor the “gate” opens or closes allowing for diffusion of specific ions.
Practice FRQ’s Ideas:
What type of communication involves a cell secreting a substance to an adjacent target cell? paracrine signaling
Plant cells in direct contact with each other can diffuse substances through these structures to communicate. What are they? Plasmodesmata
What are the three stages of cell signaling? reception, transduction, response
What is the actual “signal” being transduced in a signal transduction pathway? a ligand
How is this “signal” passed from outside to inside the cell? through transduction. During
transduction the signal is relayed by protein kinases and amplified by second messengers
Some diseases, such as cancer and diabetes, are caused by defective protein phosphatases. Explain how such a defective protein would affect a signal transduction pathway. With the defective phosphatase the pathway would never shut off causing an overproduction of molecules.
AP Bio. Cell Communication
The growth and survival of the cell is dependent on cell communication
Cells can communicate through 3 general ways
Direct- (substances pass freely through cytoplasm to adjacent cells) Ex. Immune cells
- Animals- Gap Junctions, Plants-Plasmodesmata
Local – messages secreted over a short distance from cell-to-cell via extracellular fluid.
- Synaptic-nervous systems (neurotransmitters)
- Paracrine- almost all others, release local regulators(ex. Growth hormones) via exocytosis
Long distance- hormone signaling. Ex. Insulin
- Plants- hormones through xylem and phloem (vascular tissue) or air.
- Animals- hormones through endocrine signaling. Into circulatory system.
Three stages of Cell signaling
-Reception- ligand(any macromolecule that binds to a signal molecule) is detected and then binds to receptor. This is highly specific. Lock and Key. Then it initiates Transduction. Can be plasma membrane or intracellular
- Plasma Membrane- most common, polar, hydrophilic, and large. (Ex. G-proteins, ligand gated ion channels)
- Intracellular- found in nucleus or cytoplasm. Binds to ligand that can pass through membrane (hydrophobic, small, nonpolar). (Ex. Nitric oxide/gasses, or steroids and thyroid hormones)
Stage 2: Transduction- The conversion of an extracellular signal to an intracellular signal that will bring about a cellular response
- Kinase: Adds a phosphate from ATP. Relays the signal inside
- Phosphatase: Takes a phosphate to shut off the pathway.
Second messengers are used during transduction to relay and amplify the response. They are small, non-protein molecules and ions. (Ex. Cyclic AMP or cAMP)
Stage 3: Response- The final molecule changes the signal to a response which then alters a cellular process.
- Examples: Alter membrane permeability, change metabolic process, and protein that turns genes on or off
Signal transduction pathways can influence how a cell responds to its environment. This can result in charges in gene expression and cell function. (this can alter phenotype or result in cell death)
Any sort of change (mutations) to receptor proteins or to any component of the signaling pathway will result in a change to the transduction of the signal.
In eukaryotic organisms two main cell membrane receptors are G proteins coupled receptors and ion channels
- GPCRs: Largest category of cell surface receptors, important in animal sensory systems, and binds to a G protein that can bind to GTP, which is an energy molecule similar to ATP. The GPCR enzyme and G protein are inactive until ligand binding to GPCR on the extracellular side. Ligand binding causes cytoplasmic side to change shape, allows for the G protein to bind to GPCR. Activates the GPCR and G proteins. GDP becomes GTP. Part of the activated G protein can then bind to the enzyme. Activates enzyme, amplifies signal and leads to a cellular response.
- Ion Channels: Ligand gated ion channels, located in the plasma membrane, important in the nervous system, receptors that act as a gate for ions. When a ligand binds to the receptor the “gate” opens or closes allowing for diffusion of specific ions.
Practice FRQ’s Ideas:
What type of communication involves a cell secreting a substance to an adjacent target cell? paracrine signaling
Plant cells in direct contact with each other can diffuse substances through these structures to communicate. What are they? Plasmodesmata
What are the three stages of cell signaling? reception, transduction, response
What is the actual “signal” being transduced in a signal transduction pathway? a ligand
How is this “signal” passed from outside to inside the cell? through transduction. During
transduction the signal is relayed by protein kinases and amplified by second messengers
Some diseases, such as cancer and diabetes, are caused by defective protein phosphatases. Explain how such a defective protein would affect a signal transduction pathway. With the defective phosphatase the pathway would never shut off causing an overproduction of molecules.
