Question

a 36 4.4 pN 32 11 pN 7.5 pN 5.0 pN 28 24 20 16 12 Laser trap 8 1.2 pN KT particle Tension 4 Micro- tubule 0 1.7 pN -4 -8 0 10 20 30 40 50 60 Time (min) Relative bead position (µm) This figure is from a study that looked at the effect of tension on the stability of the microtubule -kinetochore interaction. In this study they were looking at purified Kinetochores that did NOT have Aurora B. For this figure they attached a microtubule to a slide and then connected it to a kinetochore that was on a bead that they could pull on using a laser. In this figure they are graphing how much the microtubule grows over time before it looses its connection with the kinetochore. The line ends when the connection is lost a. In this figure there are three down arrows on the diagram and two up arrows. What do those arrows indicate? What might it mean that the higher tensions do not have any arrows? b. Many papers have suggested that tension is similarly important for actin stabilization at focal adhesions. i. What is a focal adhesion? ii. (3pts) What are the similarities between actin and microtubules that might cause them to both be stabilized by tension? iii. Given the roles of focal adhesions, why does it make sense that actin would be stabilized by moderate levels of tension at these sites?

          a
36
4.4 pN
32
11 pN 7.5 pN
5.0 pN
28
24
20
16
12
Laser trap
8
1.2 pN
KT particle
Tension
4
Micro-
tubule
0
1.7 pN
-4
-8
0 10 20 30 40 50 60
Time (min)
Relative bead position (µm)
This figure is from a study that looked at the effect of tension on the stability of the microtubule -kinetochore interaction. In this study they were looking at purified Kinetochores that did NOT have Aurora B. For this figure they attached a microtubule to a slide and then connected it to a kinetochore that was on a bead that they could pull on using a laser. In this figure they are graphing how much the microtubule grows over time before it looses its connection with the kinetochore. The line ends when the connection is lost
a. In this figure there are three down arrows on the diagram and two up arrows. What do those arrows indicate? What might it mean that the higher tensions do not have any arrows?
b. Many papers have suggested that tension is similarly important for actin stabilization at focal adhesions.
i. What is a focal adhesion?
ii. (3pts) What are the similarities between actin and microtubules that might cause them to both be stabilized by tension?
iii. Given the roles of focal adhesions, why does it make sense that actin would be stabilized by moderate levels of tension at these sites?

a
36
4.4 pN
32
11 pN 7.5 pN
5.0 pN
28
24
20
16
12
Laser trap
8
1.2 pN
KT particle
Tension
4
Micro-
tubule
0
1.7 pN
-4
-8
0 10 20 30 40 50 60
Time (min)
Relative bead position (µm)
This figure is from a study that looked at the effect of tension on the stability of the microtubule -kinetochore interaction. In this study they were looking at purified Kinetochores that did NOT have Aurora B. For this figure they attached a microtubule to a slide and then connected it to a kinetochore that was on a bead that they could pull on using a laser. In this figure they are graphing how much the microtubule grows over time before it looses its connection with the kinetochore. The line ends when the connection is lost
a. In this figure there are three down arrows on the diagram and two up arrows. What do those arrows indicate? What might it mean that the higher tensions do not have any arrows?
b. Many papers have suggested that tension is similarly important for actin stabilization at focal adhesions.
i. What is a focal adhesion?
ii. (3pts) What are the similarities between actin and microtubules that might cause them to both be stabilized by tension?
iii. Given the roles of focal adhesions, why does it make sense that actin would be stabilized by moderate levels of tension at these sites?

Added by Brian M.

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