Cytoskeleton System

Three main components of cytoskeleton

Microtubles, microfilaments intermediate filaments

Other polymer networks are located within cells as networks composed of proteins called

Septics

Microtubules monomers

B tublins and a tubulins

Microfilaments

G actin

Intermediate filaments monomers

Six classes of proteins variable composition

Bacteria “Cytoskeleton”

Actin like MreB protein involved in DNA segregation and cekk shape

Tubulin like FtsZ

Involved in regulating divison

Microtubles

Readily deform (bend)but break under minimal force

Actin filaments

Resist deformatiom but break under moderate force

Intermediate filaments

Readily deform with increasing force, and they resist breaking

Each end of the filament polymers has different properties and change shape when polymerase due to

Polarity

What only can be used to polymerase microtubules of micro filaments?

Triphosphate bound monomers

What binds GTP to hydrolyses GDP

Tubular

What binds to ATP TO hydrolysis to ADP

Actin

Filament shrinks

When rate of loss of subunits at one end > rate of addition at the other end

Filament elongation

Rate of addition > loss at the other

Treadmilling

Rate of addition = rate of loss

Addition of subunits

At the plus end

Removal of subunits

From the minus end

Microtubules main theme

Movement ( within the cell or fluids outside

Components of microtobules

Straight, hollow cylinders (lumin) usually 13 arrays of polymer called protofilaments

Protoflaments

heterodimer of tubulinds

Cytoplasm microtubules functions

maintains axons

Formation of spindles

Maintains or altering shape

Axonemal microtubles

Cilia flagella and basal bodies

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Microtubled formation

Reversible pokymerziation of tubulin diners in the ordenes of GTP and Mg 2+

Oligomers

Connection of dimers (seeds)

Nucleation

Process in which several tubulin molecules interact to form a microtubled seed