Microtubules

Question 1

What is the name of the protein that makes up microtubules?

Answer 1

TUBULIN

Question 2

Microtubule tubes

a single tube of microtubule is built from ____ protofilaments, but you can also have _______ and ________ tubes. These each have ___ protofilaments.

Answer 2

Microtubule tubes

a single tube of microtubule is built from 13 protofilaments, but you can also have DOUBLET and TRIPLET tubes. These each have 10 protofilaments.

Question 3

What is the name of the center where microtubules are organised?

What is the main center called?

What is the name of the center where cilia and flagella are assembled?

Answer 3

MTOCs (microtubule-organising centers

The centrosome

The basal body

Question 4

Centrosomes

Centrosomes consists of cylindrical__________ surrounded by_____________ material.
The structures consist of ______________ microtubules.
Y-TuRC acts as a helical_______________ to bind alphabeta-tubulin

Answer 4

Centrosomes
Centrosomes consists of cylindrical CENTRIOLES surrounded by PERICENTRIOLAR material.
The structures consist of NINE TRIPLET microtubules.
Y-TuRC acts as a helical TEMPLATE to bind alphabeta-tubulin

Question 5

Which protein catalyses the polymerisation of dimers into microtubules?

For assembly occur, ab dimers must be above ________________, they are added at the ___ end

When microtubules elongate there can be sudden ___________, this is called _________________. However they can also go through __________ and start growing again.

Answer 5

MAPS = microtubule-associated proteins
For assembly occur, ab dimers must be above CRITICAL CONCENTRATION they are added at the (+) end

When microtubules elongate there can be sudden DISASSEMBLY this is called CATASTROPHE. However they can also go through RESCUE and start growing again.

Question 6

What are the two major classes of motor proteins?

Answer 6

KINESINS AND DYNEINS

Question 7

Kinesin-1 Structure
Head domain is responsible for connection to ____________ and _________

Tail domain is responsible for binding to receptors on __________________.

Answer 7

Kinesin-1 Structure
Head domain is responsible for connection to MICROTUBULES and ATP.

Tail domain is responsible for binding to receptors on MEMBRANE VESICLE CARGO.

Question 8

Movement of Kinesins-1
1. Leading head in ________ free state is strongly bound to the __________, where as the trailing head in the _______ is weakly bound
2. Leading head binds _____ and remains strongly bound.

3. Binding of ATP causes a ___________ change making the ________ to swing forward and dock into the head. This move is called a __________.
4. New leading head finds a ___________ on the microtubule
5. Leading head releases ______ and become strongly bound, the trailing head hydrolyses ____ to ______ and ____, and becomes weakly bound.

Answer 8

Movement of Kinesins-1
1. Leading head in NUCLEOTIDE free state is strongly bound to the MICROTUBULE, where as the trailing head in the ADP is weakly bound
2. Leading head binds ATP and remains strongly bound.

3. Binding of ATP causes a CONFIRMATIONAL change making the LINKER to swing forward and dock into the head. This move is called a POWER STROKE.
4. New leading head finds a BINDING SITE on the microtubule
5. Leading head releases ADP and become strongly bound, the trailing head hydrolyses ATP to ADP and Pi, and becomes weakly bound.