microtubules and mitosis Flashcards
What are the main components that generate motility in microtubules?
microtubules generate motility via growth and shrinkage and interactions with motor proteins like dynien and kinesins
How do dynein motors contribute to the beating motion of cilia and flagella?
Dynein motors slide adjacent microtubule doublets against each other, creating bending motions. This coordinated activity generates the characteristic wave-like or beating motion of cilia and flagella.
What structure organizes microtubules in cilia and flagella?
axoneme structure, are organized as a circle of nine double microtubules on the outside and two microtubules in the center.
what is the role of nexin in the axoneme structure
connects mircotubules
what is the role of radial spokes in the axoneme structure
they coordinate dynein activity
role of dyein in axoneme
via ATP hydrolysis they generate the sliding force between doublets
the sliding force is converted into bending
What are the roles of microtubules and motor proteins during mitosis?
Microtubules: Form the mitotic spindle to segregate chromosomes.
Kinesins: Drive spindle elongation and chromosome alignment.
Dyneins: Pull on spindle poles to help position the mitotic apparatus.
What are the key stages of mitosis?
Prophase:
Chromatin condenses into visible chromosomes.
The mitotic spindle begins to form from centrosomes.
Prometaphase:
The nuclear envelope breaks down, allowing microtubules to attach to kinetochores on chromosomes.
Chromosomes begin moving toward the spindle equator.
Metaphase:
Chromosomes align at the metaphase plate.
Spindle microtubules stabilize.
Anaphase:
Sister chromatids separate as kinetochore microtubules shorten.
Astral microtubules pull spindle poles apart.
Telophase:
Chromosomes decondense, and nuclear envelopes reform around each set of daughter chromosomes.
The spindle disassembles.
How does microtubule organization change during mitosis?
Prophase: Interphase microtubules disassemble, and spindle microtubules form.
Prometaphase: Kinetochore microtubules attach to chromosomes.
Metaphase: Spindle microtubules stabilize at the metaphase plate.
Anaphase: Kinetochore microtubules shorten; astral microtubules elongate.
Telophase: Spindle disassembles, and interphase microtubules reassemble.
What is the difference between astral, kinetochore, and interpolar microtubules?
Astral microtubules: Radiate toward the cell cortex to position the spindle.
Kinetochore microtubules: Attach to chromosomes at kinetochores for segregation.
Interpolar microtubules: Overlap at the spindle equator to stabilize the spindle.
What is the function of the centrosome in microtubule organization during mitosis?
The centrosome serves as the main microtubule-organizing center (MTOC)
The centrosome nucleates and organizes spindle microtubules, ensuring proper bipolar spindle assembly.
