The cytoskeleton

1
The cytoskeleton
??????????????????????? ???????????????????
????????????????????????? ????????????????
cytoplasm ????????????????????????????????????????
??????????????????? ??????????????????????????????
cytoplasm ???????????????????????????????
2
The cytoskeleton
3
Motor molecules and the cytoskeleton

• Cytoskeleton ???????????? motor proteins
  ???????????????????????????????? ????
  ???????????????? flagellum ???? cilia
  ?????????????????????????????????

4

• Motor molecules ?? vesicles ???? organelles
  ???????????????????? ???????????? cytosleleton

5
Cytoskeleton ?????????????????????? 3 ??????????
Microfilaments (Actin Filaments)
Intermediate Filaments
Microtubules
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Structure of Microtubules
????????? ??????????????????????
????? tubulin
protein ???????????????????? 25 nm ??????????
?-tubulin ??? ?-tubulin
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Function of Microtubules

• ???????????????????????
• ??????????????????????????? organelles ????
• ??????????????????????????????????????????????????
  

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Microtubules ????????????? centrosome
???????????? nucleus ???????????? ??????
centrosome ?? centrioles ???? 1 ???
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Centrosome containing a pair of centrioles
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• Centrosome and centrioles
• ????????????????????????? microtubules ?????????
  centrosome ????????????????????????
• ???????? centrosome ??????????????? centrioles
  ???? 1 ??? ????? centriole ??????????
  microtubules ????? 3 ??? ????? 9 ???
  ?????????????????
• ???????????????????????????????? centrioles ????
  2 ???
• ?????? centrioles ?????????????????????????????
  microtubules ?????????????????????????????????????
  ?????????? ?????????? centrioles

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Microtubules ?????????? flagellum ??? cilia
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A comparison of the beating of flagella and cilia
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Ultrastructure of a eukaryotic flagellum or cilium
14
???????????? flagellum ???? cilia
??????????????????? EM (a) ????????????
(b) ????????????? ?????????????????????????
???????????????? microtubules ????????????????????
?????????????????????? ???????????? pattern "92"
??? ????????????????? microtubules 2 ???
(doublets) ????? 9 ???????????????????????
???????????? microtubules ??? 2 ???
????????????????????????? 1 ??? (dynein)
??????????????????????????????????????????? ?????
radial spoke ????????????????????????????????
( c) ???? basal body ????????????????? flagellum
???? cilia ???????????????????? centriole
?????????? microtubules 3 ????????????????????
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How dynein walking moves cilia and flagella
???????????????? dynein ?????????????????????????
flagellum ???? cilia ???????????????? dynein arm
??????????????????? microtubules?????
??????????????????????? ??????????????????????????
????????????? flagellum ???? cilia
?????????????????????? ??????????? dynein
????????????? ATP
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Structure of Microfilaments
????????? ????????????? 2 ????????? ??????
???? ???????????????????? 7 nm ??????????
Actin
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Function of Microfilaments

• ?????????????????????????????????????????????
• ??????????????????????????
• ?????????????????????????? ???????????????????????
  ??

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A structure role of microfilaments
Microvilli ????????????????????????????????????
microfilaments ??????? ????????????????
intermediate filaments
Microfilaments (Actin filaments)
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Microfilaments and motility
????????????????? actin filaments
???????????????????????? ?????????????????????????
???????????????????????
20
???????????? ??????? pseudopodium
????????????????????????????? actin filaments
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?????????? ?????????????????? actin ??? myosin
???????????????????? cytoplasm
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Structure of Intermediate Filaments
????????? ????????????????????????? ??????
??????????????????? ???????????????????? 6-12
nm ?????????? ??????????????
??????????? ???????? ??. ???? keratin
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Function of Intermediate Filaments

• ????? organelles ????????????
• ??????????????????????

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Plant cell walls
cell wall ???????????????????????????????????????
?????????? ???????????????????????????????
cellulose ????????????????????? polysaccharides
25
????????????????????????????????????????????
???? plasmodesmata
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Extracellular matrix (ECM)
??????????????? cell wall
??????????????????????????????????????????????????
?? ???????? extracellular matrix
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Extracellular matrix (ECM) of an animal cell
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????????????????????????? ECM ???????????????????
????????? ????????????????????????? ECM
???????????????? glycoprotein 3 ???? ?????? 1.
collagen fiber ????????????????????????
proteoglycans ?????????????????????????? 95 2.
fibronectin ???? glycoprotein ??????????????
receptor protein ????????????????????????
(integrin) 3. integrin ?????????????????? ECM
??? microfilament ?? cytoplasm ???????????????????
??????????????????????????????????????????????????
????????????????????????
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?? 3 ???? ??? 1. Tight junctions 2.
Desmosomes 3. Gap junctions
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Intercellular junctions in animal tissues
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Cellular junction ???????????? (a) tight
junction ?????????????????????????????????
???????????????????????????????????
????????????????? ???????????????????
????????????????????? ????????????????? (b)
desmosome ??????????????????????????
??????????????????????????????????????????????????
?????????????? filament ?????????????????????????
?????? (c) gap junction ?????????????????????????
????????? ????????????????? ????????????????????
20 Ao ????????????????????????????????????????????
?????????????????
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????????????????????????????????? organelles
?????????????????
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• ???????????? ????? macrophage ???? pseudopodia
  ????????????????? ????????????????? actin
  filament
• Food vacuoles ?????????? lysosome ???? lysosome
  ?????????? ER ??? Golgi
• ??????????? lysosomes ???????????? cytoskeleton
  ??????????????? ribosomes
• ????????????????????? mRNA ??????????????? DNA
  ???????????
• ??????????????????????????????????????????????
  ATP ?????????????????????? mitochondria