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15 Cards in this Set
- Front
- Back
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* Fibrous component: cellulose microfibrils |
1.
o Long strands of cellulose bundled into microfibrils and cross-linked by other polysaccharide filaments
o Synthesized by enzymes in the plasma membrane |
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Gelatinous polysaccharides: pectins |
fill the space between microfibrils o They are hydrophobic, so can hold large amounts of H_2O o Synthesized in the Rough ER and Golgi apparatus |
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* Gelatinous polysaccharides: proteoglycans |
1. o A proteoglycan has a protein core with many large polysaccharides |
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Integrins |
connect the ECM to the cytoskeleton. |
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Laminins |
are ECM crosslinking proteins |
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The Animal Cell Extracellular Matrix (ECM) |
* Fibrous component: dominated by collagen |
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What is the organizational scheme of the plant primary cell wall and the animal ECM? What dominates the fibrous and gelatinous components of each? |
Plant Primary Cell Walls *Plant primary cell walls define the primary shape of the plant cell * Fibrous component: cellulose microfibrils * Gelatinous polysaccharides: pectins *
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* The Animal Cell Extracellular Matrix (ECM) Fibrous component: dominated by collagen Gelatinous polysaccharides: proteoglycans * |
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* Tight junctions |
1. Tight junctions are cell-cell attachments composed of specialized proteins in the plasma membranes of adjacent animal cells. They are variable, dynamic, and capable of forming watertight seals. Individually, they are weak and easily broken. |
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Desmosomes |
Desmosomes connect the cytoskeletons of cells. Integral membrane attachment proteins form bridges between anchoring proteins inside adjacent cells. Intermediate filaments reinforce the connections by attaching to anchoring proteins in the cytoplasm. |
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Gap junctions |
Gap junctions connect animal cells via protein channels. Specialized proteins assemble in the membranes of adjacent cells, creating interconnected pores. They allow for rapid communication by passing regulatory molecules |
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Plasmodesmata |
Plasmodesmata are functionally similar to gap junctions in animal cells. These physical connections between plant cells consist of membrane-lined gaps in cell walls through which plasma membranes, cytoplasm, and SER can connect directly |
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What are the four major steps of cell---cell signaling? Give a brief description of each. |
Cell-Cell Signaling Steps 1.Signal reception. A receptor must be present to receive the signal 2. Signal processing. Something must happen to initiate the cell’s response 3. Signal response. Second messengers or proteins in the target cell may be activated or deactivated. Gene expression may also be altered. Signal deactivation. Cells have built-in systems to turn signals off |
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How are lipid soluble vs. lipid insoluble signals processed? |
Lipid Soluble vs. Lipid Insoluble Signals (part of Step 1)
• Ability of a signaling molecule to pass through lipid bilayers is crucial in determining how a target cell recognizes it o Most lipid soluble signaling molecules can diffuse across the hydrophobic region of the plasma membrane and enter the cytoplasm of target cells o Large or hydrophilic signaling molecules cannot cross the plasma membrane. They must be recognized at the cell surface. |
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What are two major types of signal transduction and amplification systems, and how do they work? |
Signal Transduction (part of Step 2) *Signal transduction begins at the plasma membrane. Amplification occurs inside the cell. * Two major types of signal transduction and amplification systems: 1.G-protein coupled receptors initiate production of intracellular “second messengers” that then amplify the signal 2. Enzyme-linked receptors trigger protein activation in the cell (ex. Phosphorylation) 3. In response to hormone binding, the receptor changes shape and activates its G- protein 4. The active G-protein interacts with another protein in the plasma membrane This produces a second messenger 5. Second messengers are small non-protein signaling molecules that elicit an intracellular response to the first messenger. 6. They aren’t restricted to a single role or cell type 7. More than one second messenger may be triggered by the same extracellular signaling molecule 8.
9. Enzyme-Linked Receptors (part of Step 2) Signal reception causes receptors to dimerize 10. The activated receptor complex phosphorylates itself at tyrosine residues 11. Binding proteins bind to the receptor, and one activates Ras by exchanging GDP for GTP 12. A phosphorylation cascade results, and causes some effect in the cell
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Crosstalk – know that cells can respond to various signals in an integrated manner |
Crosstalk (part of Step 3) • Signal transduction pathways form a network, so cells may respond to many signals in an integrated manner |
