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Cell/Molec III
Third Exam Material Cellular and Molecular Biology
| Question | Answer |
|---|---|
| Cytoskeleton | Dictates the shape of a cell |
| Actin | Filament that makes up cytoskeleton, smallest (example is microvilli in intestinal epithelial cells) |
| Intermediate filament | Strongest filament that dictates strength of cell (example is desmosome that attach intermediate filaments from one cell to another) |
| Microtubules | Thickest filament that is hollow and makes up transportation system inside the cell |
| Filaments | Made up of small protein subunits that are soluble, unstable and can be manipulated. Arrange in a ropelike structure to produce strength |
| Protofilaments | Single protofilaments are easier to break than multiple protofilaments which are more stable (multiple filaments coiled around one another) |
| Cytoskeleton and signals | Cytoskeleton can reshape rapidly to disassemble and move to a nutrient rich source |
| Tubulin Heterodimer | Microtubule subunit, protein that has two different parts of a two part subunit. (Alpha and Beta tubulin makes a heterodimer). Binds GTP or GDP |
| Alpha and Beta Dimer | Dimers interact, stack on top of one another. Beta exposed at the + end and Alpha exposed at the - end. Makes a helical type structure with an empty lumen (pipe) |
| Microtubule growth | Microtubules preferentially grow at + end, is dynamic. - end is relatively stable. MICROTUBULES ARE DYNAMICALLY UNSTABLE. example: spindles in mitosis and centrosomes |
| GTP cap | Determines if microtubule grows, end subunit will have GTP cap=growth. If GTP is hydrolyzed to GDP, microtubule will shrink |
| Catastrophe | Accidental loss of GTP cap |
| Rescue | Gain of GTP cap after shrinking |
| Actin | thinnest filament that gives cell shape and movement, located right underneath cell membrane (scaffolding). Alpha actin subunit makes up both + and - ends. Subunit binds ATP or ADP. |
| Nucleation | Rate limiting step in filament growth because it is the slowest step to start. More subunits yields faster growth. It is easier to break down filaments that already have nucleases and cause each piece to grow rapidly. |
| Intermediate filaments | Provide cell strength, have many different subunits, most rope-like of all filaments (coil around one another). Can withstand high levels of deforming force (microtubules most weak, actin middle strength) |
| Keratin filaments | Exist in epithelial cells, keratin genes can mutate and cause blistering (intermediate filaments are weak and cells rupture between nucleus and hemidesmosomes) |
| Vertebrates vs. Eukaryotes | Vertebrates have intermediate filaments, Eukaryotes have microtubules and actin filaments |
| Tubulin polymerization | Nucleated by gamma tubulin ring |
Created by:
jgk25
on 2011-11-27