Microtubules, Dynamic Instability and the Spindle
Microtubules grow and shrink in sudden switches rather than smoothly, which lets them search space until an end is captured and held. That search is how a spindle finds every chromosome.
What a learner can do afterwards
- Describes dynamic instability as switching between growth and rapid shrinking, and says what triggers the switch.
- Explains how search and capture attaches a spindle fibre to a chromosome without aiming.
- Predicts what a drug that freezes microtubules does to a dividing cell.
1 · Read
Microtubules do not grow smoothly. Each one switches between steady growth and rapid shrinking. A change at the growing tip flips the switch from one mode to the other.
The spindle uses this switching to search space. Many microtubules grow outward in all directions, shrink back, and grow again. The end that bumps into a chromosome is captured and held.
Picture the spindle casting out lines again and again with no aiming. Most lines miss and shrink away. The few that touch a chromosome lock on, until every chromosome is held.
A drug that freezes microtubules stops the whole search. With no growing and shrinking, no new attachments form, and the dividing cell stalls.
Switching ends search blindly, capture holds the hits, and freezing breaks division.
2 · Watch
Take it off screen
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.