Biology 2382B Lecture Notes - Lecture 12: Intermediate Filament, Ultimate Tensile Strength, Tubulin
44 views7 pages
24 Oct 2018
School
Department
Course
Professor
Document Summary
Atp form and tubulin has to be in the gtp form in order for polymerization this: actin and tubulin monomers and dimers are relatively small globular. Intermediate filaments are formed relatively large subunits isn"t the case for intermediate filaments tissues: the intermediate filaments wont break if you pull on them. Intermediate filaments is that they are cell specific good thing: 1) acidic and basic keratins: Intermediate filaments found in epithelial cells (in your skin) If you see keratin as the intermediate filament, you know its an epithelial cell: 3, desmin, vimentin together tightly. Intermediate filaments found in neurons: provide tensile strength, give strength to axons and other structures in neurons, light, medium and heavy (nfl, nfm, and mfh, these 4 are important in cancer. Ifs are in dynamic state - proteins within filament are exchanged: need to disassemble during mitosis (cyclin dependent kinase roles). N-terminal domain of lamin a phosphorylated at serine -induces disassembly, and prevents reassembly.
Get access
Grade+
$40 USD/m
Billed monthly
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
10 Verified Answers
Class+
$30 USD/m
Billed monthly
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
7 Verified Answers
Related Questions
Activity: Dynamic Instability of Microtubules
Part A
What causes catastrophe of the microtubule in vitro?
the lack of tubulin heterodimers |
non-motor Microtubule Associated Proteins (MAPs) |
GTP hydrolysis |
mutation of the β-tubulin |
Part B
What is the role of GTP in microtubule polymerization?
GTP binds the alpha and beta tubulin subunits together to form the tubulin monomer. |
GTP hydrolysis provides the energy for the polymerization of the microtubule. |
GTP is a second messenger that signals the need for polymerization/de-polymerization. |
GTP stabilizes the tip of the microtubule, allowing more monomers to be added. |
Part C
What would happen in the treadmilling experiment if a non-hydrolyzable analogue of GTP were used?
The monomers would be unable to add to the plus end, and the microtubules would shrink until they disappeared. |
The microtubule would treadmill until the new tubulin, with non-hydrolyzable GTP, reached the minus end, and then it would only extend at the plus end. |
The microtubule would add monomers at both the plus and minus ends, growing in both directions. |
The non-hydrolyzable GTP would stabilize both ends, causing treadmilling to stop. |
Part D
What is the difference between the plus and minus ends of the microtubule in in vitro experiments?
The beta subunit of the tubulin is exposed on the minus end. |
Polymerization occurs at the plus end. |
The plus end has a lower critical concentration for tubulin heterodimers. |
Catastrophe occurs at the minus end. |
Part E
How would the drug taxol affect the in vitro dynamic instability and treadmilling experiments?
Taxol would block catastrophe at the plus end in the dynamic instability experiment but not depolymerization at the minus end in the treadmilling experiment. |
Taxol would block the addition of tubulin in both experiments, leading to a destruction of the microtubules. |
Taxol would stabilize the microtubules in both experiments, leading to polymerization without catastrophe. |
Taxol would block depolymerization at the minus end in the treadmilling experiment but not catastrophe at the plus end in the dynamic instability experiment. |