Microtubules Structure

Questions and Answers

What is the diameter of a microtubule?

25 nanometers (correct)

10 nanometers

50 nanometers

100 nanometers

What is formed when alphatubulin and betatubulin join together?

A microtubule

A dimer (correct)

A trimer

A polymer

What is the function of the microtubule organizing center?

To break down microtubules

To regulate microtubule length

To anchor one end of the microtubule (correct)

To synthesize alphatubulin and betatubulin

What is the characteristic of microtubules that allows them to fulfill their functions?

Their ability to change length quickly Signup and view all the answers

What is the term for the process of adding or removing dimers to change the length of a microtubule?

Microtubule dynamics Signup and view all the answers

What is the shape of the structure formed when dimers are joined together?

A sheet Signup and view all the answers

What is the term for the end of the microtubule where dimers can be added or removed quickly?

The dynamic end Signup and view all the answers

How many types of microtubule organizing centers are mentioned in the content?

Two Signup and view all the answers

What is the main function of centrioles during mitosis?

To duplicate and form a pair on either side of the cell Signup and view all the answers

What is the structure composed of nine triplets of microtubules?

Centriole Signup and view all the answers

What is the protein on the chromosome that serves as an anchoring site for microtubules?

Kinetichore Signup and view all the answers

What is the name of the microtubules that are attached to the centrioles and run between the two poles of the cell?

Interpolar microtubules Signup and view all the answers

What is the purpose of the centrosome in a cell?

To organize microtubules during mitosis Signup and view all the answers

What is the term for the blue fibers that hold the chromosomes in a specific way during metaphase?

Mitotic spindle fibers Signup and view all the answers

How many microtubules make up one centriole?

27 Signup and view all the answers

What is the term for the part of the centriole that contains the microtubules and is located near the poles of the cell?

Astral region Signup and view all the answers

During which stage of mitosis do the centrioles duplicate and form a pair on either side of the cell?

Cell replication Signup and view all the answers

What is the name of the organelle that is found near the nucleus of a cell and is composed of proteins and centrioles?

Centrosome Signup and view all the answers

What is the name of the structure that forms a star-like shape during mitosis?

Aster Signup and view all the answers

What is the purpose of the mitotic spindle?

To separate chromosomes during anaphase Signup and view all the answers

What is the function of centrioles?

To organize microtubules Signup and view all the answers

What type of microtubule organizing center is found in cells with cilia or flagella?

Basal body Signup and view all the answers

What is the function of flagella in human cells?

To help the cell move Signup and view all the answers

What is the difference between cilia and flagella?

Cilia are shorter and flagella are longer Signup and view all the answers

What is the name of the structure that consists of centrioles plus other proteins?

Centrosome Signup and view all the answers

What happens to the microtubules during anaphase?

They become shorter Signup and view all the answers

What is the purpose of the mitotic spindle in anaphase?

To separate chromosomes Signup and view all the answers

Where are basal bodies typically found?

In cells with cilia or flagella Signup and view all the answers

What is the specific arrangement of microtubules in a cilium or flagellum?

9 + 2 arrangement Signup and view all the answers

What is the protein that helps to keep microtubules in their place in a cilium or flagellum?

Nexin Signup and view all the answers

What is the function of dynein in a cilium or flagellum?

To break down ATP and help microtubules move past each other Signup and view all the answers

What is the role of microtubules in internal transport in neurons?

To transport substances from the soma to the axon or synaptic terminal Signup and view all the answers

What are the two proteins that help shuttle substances along the microtubule railroad track in neurons?

Dynein and kinesin Signup and view all the answers

What is one type of substance that can be shuttled down the microtubule railroad track in neurons?

All of the above Signup and view all the answers

What is the process called that involves the transport of substances from the soma to the axon or synaptic terminal in neurons?

Axonal transport Signup and view all the answers

What is the significance of microtubules in the transport of synaptic vesicles in neurons?

They transport synaptic vesicles from the soma to the synaptic terminal Signup and view all the answers

What is the role of microtubules in the transport of organelles in neurons?

They transport organelles from the soma to the axon or synaptic terminal Signup and view all the answers

What is the function of kinesin and dynein in axonal transport?

To shuttle substances along the microtubule railroad track Signup and view all the answers

Study Notes

Microtubule Structure

Microtubules are made up of two proteins: alphatubulin and betatubulin
These proteins join to form a dimer, which then form long chains or polymers
These polymers are arranged in a sheet-like structure, which is then rolled up to form a tube
The diameter of a microtubule is approximately 25 nanometers
Microtubules are dynamic, meaning they can change length quickly by adding or removing dimers at one end

Microtubule Organizing Centers (MTOCs)

MTOCs are structures that anchor microtubules
There are two types of MTOCs: centrosomes and basal bodies
Centrosomes are found near the nucleus in eukaryotic cells and are involved in mitosis
Basal bodies are found in cells with cilia or flagella and are involved in the formation of these structures

Centrosomes

Centrosomes are composed of two centrioles and other proteins
Each centriole is made up of nine pairs of microtubules (9+2 arrangement)
Centrioles duplicate during mitosis and move to opposite poles of the cell
Microtubules from the centrioles form the mitotic spindle, which separates chromosomes during mitosis

Basal Bodies

Basal bodies are found in cells with cilia or flagella
They have a similar structure to centrioles, with nine pairs of microtubules (9+2 arrangement)
Cilia and flagella are hair-like or tail-like projections that help move substances or the cell itself

Microtubule Functions

Microtubules play a crucial role in the internal transport of neurons
They form a network that runs from the soma to the synaptic terminal
Different substances, such as synaptic vesicles, proteins, and lipids, are transported along this network with the help of kinesin and dynein proteins
Microtubules also play a role in the transport of nerve signals by transporting synaptic vesicles to the synaptic terminal

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Description

This quiz covers the structure of microtubules, including their composition and formation. Learn about the role of alphatubulin and betatubulin in microtubule formation.