The Cytoskeleton Flashcards
What are the 4 components of the cytoskeleton?
Actin filaments, microtubules, actin microfilaments and intermediate filaments
What are the dimers that make up the microtubule?
Dimers of alpha and beta tubulin
What do alpha and beta tubulin both bind?
GTP (B tubulin can have its GTP hydrolysed to remove a phosphate and produce GDP)
What are lines of tubulin dimers called?
Protofilaments
How many protofilaments make up a microtubule?
13
What is the diameter of a microtubule?
24nm
What occurs at the positive end of the microtubule?
A and B tubulin both bound to GTP add at the positive end in polymerisation
What occurs at the negative end of the microtubule?
A and B tubulin bound to GDP is removed in depolymerisation
IF that GTP concentration is low what will happen to the microtubule?
It will shrink as no polymersation occurs but depolymersation still occurs
What is a microtubule organisning centre?
Where microtubules assemble
Give an example of a MTOC?
The centromere which contains two centrioles from which microtubules form the mitotic spindle in cell division
What happens to microtubules in low temperature?
Depolymeristion occurs at the microtubule shrinks
What happens to microtubules in high temperatures?
Polymerisation occurs at the microtubule grows
What two drugs can bind tubulin and prevent polymerisation?
Colchicine and Colemid
How are microtubules stability regulated?
Through microtubule associated proteins (MAPs)
What proteins are used to move cellular components along microtubule?
Kinesins and dyneins
What way do kinesins drive along the microtubule?
Toward the positive end
What way do dyenins drive along the microtubule?
Toward the negative end
What drug binds to the posotive end of F-actin and prevent polymerisation?
Cytochalasin
What is actin bound to when it is added to the positive end?
ATP
What is actin bound to when it removed from the negative end?
ADP
How long is an intermediate filament?
10nm
What is the basic structure of an intermediate filament?
A nitrogen head, a carbon tail and a rod in the middle
How do intermediate filaments assemble?
By mutlmerisation - make dimers that then combine to make tetramers
Give an example of something whose shape is controlled solely by actin filaments?
Human ethythrocytes and microvilli
How are microtubules involved in bicoid distrubutuon?
They move them into the oocyte via microtubules with kinesin motors
