cytoskeleton; intermediate filaments Flashcards

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1
Q

where are they found

A
  • nearly all mammal cells
  • absent from plants and fungi
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2
Q

structure and function

A

rope like network of filaments
principal function is to maintain cell structure and tensile strength

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3
Q

IF differ from AF and MT

A
  • no defined polarity
  • no associated motor proteins
  • dont bind to nucleotides; ATP, GTP
  • very stable in comparison
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4
Q

4 types of IFs

A
  • cytoplasmic; keratins, vimentin and vimentin related, neurofilaments
  • nuclear; nuclear lamins
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5
Q

function of IF in cytoplasm

A
  • tensile strength; withstand mechanical stress
  • structural support; creating deformable 3D structure, reinforcing cell shape and fix organelle localisations
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6
Q

stratified squamous epithelium

A
  • stem cells interior
  • dead cells at outmost surface
  • keratin remains; hard, waterproof, resists abrasions
  • makes up hair, nails, skin, feathers
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7
Q

what do keratins do?

A

form strong network indirectly linked to neighbouring cells

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8
Q

hemidesmosomes

A

mediate cell-matrix adhesion between epithelial cells and basal lamina
- integrins a6b4 binds to proteins in plaques to lamin in ECM

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9
Q

what does disruption of keratin networks cause

A

blisters

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10
Q

vimentin required for what

A

trans-epithelial migration

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11
Q

endothelial migration

A

WBCs leave blood stream to combat infection
- process impaired in mutant mice

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12
Q

desmin filaments function

A

maintain muscle structural integrity
mutant mice=misaligned muscle fibres
mutations in humans = muscle disorders

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13
Q

desmin filaments structure

A

tethered to Z disk like sarcomere

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14
Q

neurofilaments

A

have side arm projections from core filaments
fill and pack cytoplasm with neurons

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15
Q

charcot-marie-tooth disease

A

peripheral nervous system degenerates

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16
Q

functions of IF in the nucleus

A
  • in all nucleated euk cells
  • form mesh rather than rope like structure
  • line in inner face of nuclear envelope and give ; strength, provide attachment for chromatin
17
Q

IF and cell division

A

reform at each division
- very different from cytoplasmic IFs
- controlled by post-trans mods.
- form basket like structure on inner side of nuclear membrane that protects structure
- disassemble when cells enter mitosis

18
Q

IFP; IF binding proteins

A
  • mainly linkers of IF structures
19
Q

stabilise and reinforce IF into 3D networks

A
  • fillagrin; binds keratin into bundles
    -synamin and plectin; bind vimentin and desmin
  • plakins; contact between desmosomes + epthelial cells