Cytosquelette 2: Microtubules Flashcards
What makes up mictotubules?
Composed of tubulin heterodimers
alpha and beta tubulin
What is the energy souce for microtubules and where does it bind?
Tubulin binds GTP
Where does nucleation happen in microtubules?
Nucleation happens from the centrosome
Centrosomes are formed from centrioles
Centrioles are super stable microtubules
What makes up the centrosome?
Centrosomes are formed from centrioles
Centrioles are super stable microtubules
What is the role of GTP in microtubules?
Microtubules are Polarized using GTP bound heterodimers
Takes minutes to build and will build as long as there is GTP bound
The head will have GTP bound while the tail depolarizes
Needs to be continuous adding of GTP bound heterodimers
When there is no more GTP → des-stabilized structure → rapid breakage → catastrophe
All of the microtubule is undone
What are the two main motor molecules for microtubules and what is their direction?
Kinesin: Anterograde (towards +)
Dynein: Retrograde (towards -)
What is the role of microtubules diring cell division?
Essentiel pour coordonner (alignment of) les chromosomes pendant la
division cellulaire
What are the two bolime structures formed by microtubules?
Microtubes form cilia and flagella:
What are the 2 types of cilia that can be formed?
9+2 Conformation → Motile Cilia :
- Much longer than microvilli
- Found in trachea, ependyme cells, fallopian tubes
9+0 Conformation → Non-motile cilia:
- Only found in quiescence cells: G0
- Cells that are not doing cell cycle
- Only one per cell!!!
- Important for signalization:
- Mechanoreceptor or Antenna
What motor protein is responsible for the movement of flagella and cilia, and what molecule does it use for this motion?
The dynein motor protein is responsible for the beating and movement of flagella and cilia. It uses ATP for this motion.
What is the difference between primary and motile cilia?
In terms of structure, primary cilia lack the central pair of microtubules, which explains their lack of motility.
They are far more widespread than the motile type.
For example, in humans, only a few cell types have motile cilia, namely sperm, epithelia cells in the bronchi and oviducts, and ependymal cells that line brain vesicles.
But virtually all other cells have a primary cilium.
A cell will typically have one primary cilium. This applies to most types of cells.
However, it’s important to note that some cells can have many motile cilia. For example, respiratory epithelial cells can have around 200 motile cilia per cell.
What is the role of kinetochores in cell division? a. They attach microtubules to chromosomes b. They separate sister chromatids c. They synthesize new DNA d. They regulate the cell cycle
They attach microtubules to chromosomes
What is the function of primary cilia in cells? a. To propel the cell through fluid environments b. To sense mechanical or chemical signals from the environment c. To transport materials across the cell membrane d. To generate ATP for cellular energy
b. To sense mechanical or chemical signals from the environment
What is the name of the structure that serves as the base for cilia and flagella? a.Basal body b.Centriole c.Centrosome d.Complexes d’anneaux
Answer: a.Basal body
How does dynein cause the beating and movement of flagella and cilia? a.Dynein uses ATP to slide adjacent microtubules past each other b.Dynein uses ATP to rotate the microtubules around their axis c.Dynein uses ATP to shorten or lengthen the microtubules d.Dynein uses ATP to bend or twist the microtubules
a.Dynein uses ATP to slide adjacent microtubules past each other
