cytoskeleton

classes of cytoskeleton

• actin filaments

• intermediate filaments

• microtubules

actin is found in

all eukaryotic cells

actin filaments are

a polymer made up of actin monomers

exists as a globular protein 

why are rings of actin important in axons

maintain the structure and diameter of axon

therefore important for action potentials

actin is organised in

bundles or meshed networks/branched arrays

actin is important for

force exertion

cell movement

cell division

actin based structures in motile cells

• stress fibres

• lamellipodium

• filopodia

actin in yeast cells/yeast budding

high density of actin at edges of yeast budding

the actin filaments force the yeast cells to divide/ cytoplasm to divide

mutations in actin cause multiple disorders including

muscular dystrophy

haemolytic anaemias

a sarcomere is

the basic unit of contractile muscle fibres

composed to actin and myosin

myosin II is a

motor protein that interacts with F-actin

classes of intermediate filaments

• keratins → in epithelia

• vimentin & vimentin-related → in connective tissue, muscle cells, glial cells

• neurofilaments → in nerve cells

• nuclear lamins → in all animal cells

when pressure is applied on cells

the tension can spread across the intermediate filaments

keratin monomers are

fibrous proteins

microtubules originate in

MTOCs such as the centrosome

MTOC

microtubule organising centre

point where polymerisation starts

why are microtubules in cilia in lung cells important

for sweeping away mucus, keeping pathogens away

kinesin

type of motor protein that act on microtubules

from minus to plus end

dynein 

type of motor protein that acts on microtubules

move from plus to minus end

movement of motor proteins along microtubules

use ATP to generate kinetic energy and carry proteins, RNA, vesicles, organelles etc. along

lamins are

intermediate filaments that support the nuclear envelope

centrosome is

cell’s organising centre for microtubule growth