Terminology

You should know, what these terms mean and you should be able to explain them in your own words.

microtubules . microfilaments . intermediate filaments . microfibrils . posttranslational modification . isotype . MAPs . kinesins . dyneins . myosins . coassembly . cosedimentation . preprophase band . phragmoplast . cortical microtubules . reinforcement mechanism . microtubule-microfibril hypothesis . katanin . lodging .

1. How does the  ratio between lateral and longitudinal stress change in a cylindrical cell, when the diameter doubles?  

2. Actin and microtubules often run in parallel. How many actin filaments are needed to completely cover one microtubule?

3. When roots are treated with the microtubule-eliminating alkaloid colchicin, they swell laterally just behind the root tip. Can you explain this?

4. You measure a dose response curve for the inhibition of hypocotyl growth over the microtubule inhibitor Oryzalin in Arabidopsis thaliana for the wild type and for a mutant, where microtubule turnover is decreased due to a overexpression of MAP65. Sketch down, how the curves look like. Oryzalin acts by sequestering tubulin heterodimers from Integration into the growing microtubules (whereas the shrinking at the minus-end goes on).