16D Assignment Flashcards
Which of the following is not a descriptor of microtubules (MTs)?
25 nm diameter
hollow
flexible
polar
exhibit dynamic instability
flexible
Which of the following are well-studied roles for the microtubule cytoskeleton?
collaborate with MTOCs to add organization to the cytoplasm
provide tracks for axonal transport in neurons
provide structure and binding surfaces that are used to drive motion in cilia and flagella
provide tracks for moving organelles
All the choices
All the choices
A single neuron extends from the base of your spine to the tip of your big toe. In a tall person, this one cell can be a meter-long! Amazingly, a single mitochondrion (1 um) can transit this distance, using MTs and associated motor proteins, in a single day. That is a journey of 1 million body lengths. Under your own power, could you travel 1 million body lengths in a day? (hint: A 2 m tall person would need to run 2000 km, or 1243 miles). Even if you are really short and really fast you don’t have much of a chance.
Easily!
Very very very very unlikely!
Very very very very unlikely!
Once an alpha/beta-tubulin is assembled with an encapsulated GTP we can consider it a reusable “building block” for the purposes of discussing polymerization.
True
False
True
MTs exist in a single form within the cell, which is as a singlet tube.
True
False
False
The guiding concept of Cc is similar for actin filaments and MTs.
True
False
True
When talking about MT polymerization in vivo, it is common to emphasize the + end. What set of structures is most relevant to this emphasis?
MT-specific motor proteins
nuclear pores
Ribosomes
Microtubule organizing centers
Mitochondria
Microtubule organizing centers
Cc(T) < Cc(D):
T form refers to _____ and D form refers to _____.
ATP, ADP
GTP, GDP
ATP or GTP, ADP or GDP
ATP or GTP, ADP or GDP
If the Cc(+) is 5 uM, and the Cc(-) is 12 uM for a given MT polymerization experimental setup, and there is 14 uM purified tubulin subunits added to a reaction containing seeded MTs, what behavior would you expect to observe at the plus and minus ends, respectively?
grow, grow
grow, shrink
shrink, shrink
shrink, grow
grow, steady
grow, grow
If the Cc(+) is 5 uM, and the Cc(-) is 12 uM for a given MT polymerization experimental setup, and there is 12 uM purified tubulin subunits added to a reaction containing seeded MTs, what behavior would you expect to observe at the plus and minus ends, respectively?
grow, grow
grow, shrink
shrink, shrink
shrink, grow
grow, steady
grow, steady
If the Cc(+) is 5 uM, and the Cc(-) is 12 uM for a given MT polymerization experimental setup, and there is (i) 14 uM purified tubulin subunits, and (ii) 20uM stathmin added to a reaction containing seeded MTs, what behavior would you expect to observe at the plus and minus ends, respectively?
grow, grow
grow, shrink
shrink, shrink
shrink, grow
grow, steady
shrink, shrink
If the Cc(+) is 5 uM, and the Cc(-) is 12 uM for a given MT polymerization experimental setup, and there is 14 uM purified tubulin subunits added to a reaction containing MTs seeded on gamma-tubulin ring complexes, what behavior would you expect to observe at the plus and minus ends, respectively?
grow, grow
grow, shrink
shrink, shrink
shrink, grow
grow, steady
grow, steady
This high-resolution image has a small field of view (about 30x50 um) focused on rhodamine-stained MTs in a newt lung epithelial cell. In this small area MTs 1-4 are likely experiencing very similar concentrations of tubulin, yet they exhibit different behaviors. From 0 to 125 seconds _____ grows, _____ shrinks, and _____ stays about the same.
2, 1, 3
1, 2, 3
3, 1, 2
3, 2, 1
2, 3, 1
3, 1, 2
The experiment pictured in question 11 documents the phenomena of dynamic instability.
True
False
True
What effect would the addition of a non-hydrolyzable GTP analog have on the frequency of GFP-EB1 signal disappearance? For example, disappearance as seen here in Panel 4.
decrease
increase
no change
decrease
