Created by gina_evans0312
almost 11 years ago
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Question | Answer |
Reason for Cellular Transporters | Diffusion is too slow for the cell to rely on it |
Role of Transport Proteins | For direct, organised and regulated transport |
Giant Squid Axon | Where motor proteins were first found |
Anteriograde transport | Towards axon |
Retrograde transport | Towards cell body |
ATP | Required for continued transport |
Protein that makes up microtubules | Tubulin- made of alpha/beta dimers |
Distance between each motor protein binding site | 8nm |
Size of microtubules | 13 protofilament tracks |
+ve end of microtubule | Where tubulin is added |
-ve end of microtubule | Where tubulin is removed |
Microtubule ATP requirement | For microfilament assembly |
No of Kinesin types in cell | 50 |
Kinesin | |
Kinesin Superfamily | G-Protein |
Direction of Kinesin movement | From minus end to plus end |
Structure of Kinesin 1- Chains | 2 light (70kDa) and 2 heavy (120kDa) |
Design of Kinesin 1 - Cargo binding | Near C terminus |
Design of Kinesin 1 - Stalk | Coiled coil structure, connecting cargo and microtubule binding sites |
Design of Kinesin 1 - Microtubule binding sites | N terminus- 2 NTPase head motors |
Design of Kinesin 1 - Neck Linkers | Connect NTPase heads to coiled coil stalk |
Role of Neck linker | For power stroke |
Role of coiled coil stalk | Connectivity and control |
Sliding assay | Bind protein to glass, and see if it can move free microtubule |
Rate of Kinesin movement | 800nm/second |
Processive movement | Movement that can only occur by following a strict process |
Monomeric heavy chain kinesin mutants | Slow and non-processive |
Potential Models for movement of Kinesin | Inchworm and Hand Over Hand models |
Optical Trap | Use latex bead as cargo and use this method to measure it's movement |
Inchworm Model | First head moves, second one catches up in 8nm steps |
Hand Over Hand model | Each head moves 16nm- leading and trailing heads swap over |
Determining Kinesin Movement Method | Label one head of Kinesin with a fluorophore and see how far it moves |
Precision of Fluorophore Method | 1nm |
Shows long lived, non moving stable state and 16nm steps | |
Role of Switch's I & II | Detect presence of terminal (gamma) phosphate of ATP |
Movement of Switch II | A spring loaded gate moving in/out in response to gamma phosphate |
ATP Binds to sensor | Engaging it- phosphate release, releases sensor |
ATP binding & sensor relationship | ATP binding engages sensor and vice versa |
Relay Helix | Relays movement of Switch II around the protein |
Conformational changes of ATP binding | Neck linker and tubular binding domain |
12 amino acid loop | Binds kinesin to tubulin |
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