Chapter 9 Flashcards
What is the cytoskeleton?
Known as the skeletal system of eucaryotic cells
What is the cytoskeleton composed of?
Microtubules, actin filaments, and intermediate filaments
Functions of cytoskeleton components
- Provide structural support and maintain cell shape
- Positions various organelles in the cell
- Direct movement of material and organelles within cell
- Generates force is needed for cellular locomotion
- Makes up important part of cell division machinery
Describe the structure and composition of microtubules
Hollow, relatively rigid, tubular, assembled from protein
How are microtubule proteins arranged?
Longitudinal rows called protofilaments
What are protofilaments?
Assembled from dimeric building blocks consisting of one alpha tubulin and one beta tubulin subunits
What is the function of microtubule associated proteins?
Increased ability and promote microtubule assembly by linking tubulin subunits together
What are the functions of microtubules?
Service tracks for variety of motor proteins that generate force is required to move objects within a cell
Three super families of microtubules
Kinesin and dyeins, myosin
What is Kinesin?
Tetramer of two identical heavy and two identical light chains, smallest and best understood microtubule motor
Globular heads bind microtubules and act as what?
ATP hydrolyzing, force generating engines
Kinesin movement is like:
Hand over hand mechanism
What is cytoplasmic dynein?
Huge protein, two identical heavy chains, variety of intermediate and light chains
Cytoplasm dynein moves how?
Along microtubule toward polymers minus end, positions centrosome and Golgi complex
Cytoplasmic dynein purpose is what?
Moves organelles, vesicles, and particles through cytoplasm
What do microtubule organizing centrecontrol?
- Number of microtubules
- Polarity of microtubules
- Number of protofilaments
- Time and location of assembly
What is a centrosome?
Major sight of microtubule initiation in animal cells and remains at centre of cells in microtubule Netwerk
What is a basal body?
Another type of MTOC that forms a base of cilium or flagellum, can turn into centrioles
Can microtubule shorten, lengthen, disassemble, and reassemble?
Yes
What is microtubule stability determined by?
Interacting proteins
Disassembly of microtubules can be initiated by what?
- Post translational modification
- Cold temperature
- Hydrostatic pressure
- Elevated calcium
- Variety of chemicals