Introduction to Cytoskeleton and Cell Matrix Interaction
- 1. Cytoskeleton Kuldeep Gauliya kuldeepgauliya11@gmail.com Ph.D., Dept. of Biotechnology DHSGSU, Sagar Holding It Together, So You Dont Have To
- 2. Other Cell Organelles Legend Cytoskeleton
- 3. Concept: The cytoskeleton is a network of fibers that organizes structures and activities in the cell The cytoskeleton is a network of fibers extending throughout the cytoplasm It organizes the cells structures and activities, anchoring many organelles It is composed of three types of molecular structures: Microtubules Microfilaments Intermediate filaments
- 5. Microfilaments Fine, thread-like protein fibers, 3-6 nm in diameter. Composed predominantly of a contractile protein called actin, which is the (most abundant cellular protein) Microfilaments' association with the protein myosin is responsible for muscle contraction. Microfilaments can also carry out cellular movements including gliding, contraction, and cytokinesis.
- 6. Intermediate Filaments Intermediate filaments are about 10 nm diameter and provide tensile strength for the cell.
- 7. Microtubules Cylindrical tubes, 20-25 nm in diameter. Subunits of the protein tubulin--these subunits are termed alpha and beta. Microtubules act as a scaffold to determine cell shape, and provide a set of "tracks" for cell organelles and vesicles to move on. Microtubules also form the spindle fibers for separating chromosomes during mitosis. When arranged in geometric patterns inside flagella and cilia, they are used for locomotion
- 8. Roles of the Cytoskeleton: Support, Motility, and Regulation The cytoskeleton helps to support the cell and maintain its shape It interacts with motor proteins to produce motility Inside the cell, vesicles can travel along monorails provided by the cytoskeleton Recent evidence suggests that the cytoskeleton may help regulate biochemical activities
- 9. Fig. 6-21 Vesicle ATP Receptor for motor protein Microtubule of cytoskeleton Motor protein (ATP powered) (a) Microtubule Vesicles (b) 0.25 袖m
- 10. 10 袖m 10 袖m 10 袖m Column of tubulin dimers Tubulin dimer Actin subunit 25 nm 7 nm Keratin proteins Fibrous subunit (keratins coiled together) 812 nm
- 11. Cytoskeleton Review What are 3 roles of the cytoskeleton? Maintain shape, mechanical support, cell motility There are 3 main types of fibers that make up the cytoskeleton what are they? Microtubules, microfilaments, intermediate filaments Microtubles are hollow rods. What are four functions of microtubules? Maintenance of cell shape, cell motility, chromosome movement during cell division, organelle movement
- 12. Cytoskeleton Review Microfilaments are solid. What is their function in a cell? Movement Intermediate filaments are bigger than microfilaments but smaller than microtubules. What is their function? Maintenance of shape, anchorage, and formation of nuclear lamina
- 13. Microtubules Microtubules are stiff, hollow unbranched and inextensible tube found in all eukaryotes. Its function: to support cell structure and intracellular transport and cell organization. The diameter of the microtubule fibre is 25 nm with GTP-留硫 tubulin heterodimers as protein subunits (monomers). The addition of tubulin incorporation is on the Beta tubulin + end. Tubulins are associated with MAPs and Kinesin and dyenin motor proteins.
- 15. Microtubules
- 16. Microtubules The formation of microtubule in vitro occurs through 2 stages of nucleation and elongation in the MTOC. 1. Free 留硫-tubulins dimmers aggregate to form short filaments called protofilaments (this stage is also known as nucleation) 2. Proto-filament associates into lateral sheets with the addition of more tubulin dimer monomers. 3. The sheet conformation is unstable, hence, they wrap around to form circular tube with 13 protofilaments - microtubule 4. Free 留硫-tubulins are GTP bounded in the 硫-subunit, which is hydrolyzed after incorporation.
- 17. Microtubules 5. Motor Proteins kinesin and dyneins are associated with tubulins. They are responsible for transport or translocation of organelles, vesicles on the microtubule. Kinesin moves from - end to +end and dyenin from + end to - end. Microtubule subunits are in a state of constant flux, i.e., polymerization and depolymerisation are continuous - state of dynamic instability. The stabilization of microtubule is effected by binding of GTP to the subunits at the ends which prevents depolymerisation. The average half-life of microtubule ranges from 10min in non- dividing cell to 20 sec in dividing cell.
- 18. Microtubules Fig. : Transport of vesicles/ organelles to and fro Endoplasmic Reticulum-Golgi ApparatusPlasma Membrane. Note;- kinesin moves from - to + end; In dynein from + to - end
- 19. Microtubules