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biochemistry > microtubules > Flashcards

microtubules Flashcards

1
Q

How do microtubules generate motility within cells?

A

Through interactions with motor proteins like kinesin and dynein, which move cargo along microtubule tracks

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2
Q

What role does kinesin play in microtubule-based motility?

A

Kinesin moves cargo toward the plus end of microtubules, usually from the cell center toward the periphery.

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3
Q

What role does dynein play in microtubule-based motility?

A

Dynein moves cargo toward the minus end of microtubules, typically transporting it toward the cell center.

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4
Q

How do microtubules contribute to the movement of cilia and flagella?

A

By forming axonemes, structures with microtubules and dynein arms that slide to create bending motion in cilia and flagella

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5
Q

What is an axoneme?

A

The core structure of cilia and flagella, consisting of a “9+2” arrangement of microtubules and dynein motors that generate movement.

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6
Q

How does dynein generate motility in cilia and flagella?

A

Dynein arms attached to one microtubule doublet “walk” along an adjacent doublet, causing bending that produces ciliary or flagellar motion.

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7
Q

What is the role of microtubules in mitotic spindle formation?

A

responsible for the separation and distribution of chromosomes to daughter cells

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8
Q

How does microtubule polymerization and depolymerization contribute to motility?

A

By rapidly assembling and disassembling, microtubules can push or pull structures, aiding in cellular processes like mitosis and cell migration.

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9
Q

What is the basic structure of cilia and flagella?

A

They have an axoneme structure with a “9+2” arrangement of microtubules: nine doublets in a ring around two central singlet microtubules.

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10
Q

What role do dynein motors play in the movement of cilia and flagella?

A

Dynein motors attach to one microtubule doublet and “walk” along an adjacent doublet, creating sliding forces

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11
Q

How does dynein activity result in the bending of cilia and flagella?

A

Dynein-generated sliding between microtubule doublets is constrained by linking proteins, converting sliding into bending.

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12
Q

What is the role of nexin in cilia and flagella?

A

Nexin is a linking protein that connects adjacent microtubule doublets, helping to translate sliding forces into bending

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13
Q

How is the beating pattern of cilia and flagella regulated?

A

The coordinated activation and inactivation of dynein arms along the axoneme generate rhythmic bending patterns.

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14
Q

What is the role of the central pair of microtubules in cilia and flagella?

A

The central pair of singlet microtubules may help regulate dynein motor activity and coordinate the beating pattern.

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15
Q

How do cilia and flagella differ in their beating motion?

A

cilia beat in a back and forth motion
flagella beat in a wave motion

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16
Q

How does ATP influence dynein and microtubule interaction in cilia and flagella?

A

ATP provides the energy for dynein to “walk” along microtubules, which is essential for generating the sliding and bending forces.

17
Q

What role do microtubules play in mitosis?

A

They form the mitotic spindle, which organizes and separates chromosomes during cell division.

18
Q

What are the three types of microtubules in the mitotic spindle?

A

Kinetochore microtubules, polar microtubules, and astral microtubules

19
Q

What is the function of kinetochore microtubules?

A

They attach to chromosomes at the kinetochores and pull sister chromatids apart during anaphase.

20
Q

What is the function of polar microtubules?

A

They overlap with microtubules from the opposite pole, helping push the spindle poles apart during anaphase

21
Q

What is the function of astral microtubules?

A

They anchor the spindle poles to the cell cortex, helping position the spindle within the cell

22
Q

What role does the motor protein dynein play in mitosis?

A

Dynein helps anchor astral microtubules to the cell cortex and aids in pulling the spindle poles apart.

23
Q

What role does the motor protein kinesin-5 play in mitosis?

A

Kinesin-5 pushes polar microtubules from opposite spindle poles apart, assisting in spindle elongation during anaphase

24
Q

How do microtubules and motors contribute to chromosome alignment during metaphase?

A

Kinetochore microtubules, along with motor proteins, generate forces to align chromosomes at the metaphase plate

25
Q

How does depolymerization of microtubules aid in chromatid separation?

A

Depolymerization at the kinetochore microtubule ends generates force to pull sister chromatids toward opposite poles in anaphase

26
Q

What is the role of kinesin-4 and kinesin-10 in mitosis?

A

These motors help move chromosomes along microtubules toward the metaphase plate during prometaphase.

27
Q

What are the main stages of mitosis?

A

Prophase, prometaphase, metaphase, anaphase, and telophase.

28
Q

What happens to microtubules during prophase?

A

Microtubules begin to reorganize, and the mitotic spindle starts forming as centrosomes move to opposite poles

29
Q

What changes occur in microtubule organization during prometaphase?

A

The nuclear envelope breaks down, allowing spindle microtubules to attach to kinetochores on chromosomes.

30
Q

How are microtubules organized during metaphase?

A

Kinetochore microtubules align chromosomes along the metaphase plate, with polar microtubules overlapping at the spindle equator.

31
Q

What is the role of kinetochore microtubules in metaphase?

A

They attach to chromosomes at the kinetochores, holding them in place at the metaphase plate

32
Q

How does microtubule organization change during anaphase?

A

Kinetochore microtubules shorten, pulling sister chromatids to opposite poles, while polar microtubules lengthen to push the poles apart

33
Q

What is the role of astral microtubules during anaphase?

A

They interact with the cell cortex, helping position the spindle and pull the spindle poles apart.

34
Q

What happens to microtubules during telophase?

A

The spindle disassembles, and microtubules reorganize to support the reformation of the nuclear envelope around separated chromosomes

35
Q

How does cytokinesis relate to microtubule organization?

A

Although not part of mitosis, microtubules position the cell’s center, helping the actin-myosin contractile ring divide the cytoplasm

biochemistry (9 decks)

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